# Stihl 056 bosch ignition



## blind hog (Nov 4, 2010)

Recently solved my Stihl 056 Bosch ignition problem. After visiting this and other websites looking for answers to the "it runs for about 20 minutes and then dies" problem, I discovered many people having the same issue. My saw finally quit firing at all. I'm sure someone has already posted this solution but i haven't seen it. It's fairly obvious that the bottom (detachable) portion of the ignition unit is the coil. Cut the jumper wire from the coil to the (epoxy filled) electronics, solder this lead to a 1118-400-1001 trigger unit lead (26.00 from stihl dealer), ground the module, and the ignition will fire, assuming that the coil itself is not the issue but rather the electronics. Strangely enough the saw still would not fire. Blaming the lack of combustion on ignition timing, I pulled the key out of the crankshaft and began rotating the flywheel a few degrees in either direction. Retarding the flywheel (clockwise) about half a keyway created the desired response. I undoubtedly need to fine tune the ignition timing, but the saw runs perfectly. I then removed the top (detachable) bosch trigger unit and bandsawed off the (epoxy filled) electronics in order to mount the new trigger unit properly.


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## blind hog (Nov 4, 2010)

Correction, advanced flywheel (counterclockwise) half a key.


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## hotshot (Nov 4, 2010)

*Great idea, do you have any pictures?*

That's a great idea, did you take any photos along the way?

You can now mark the top dead center position on the case & flywheel, print a degree wheel from one the many old timing posts on the site, then mark the case again at 26 BTDC. Hook an automotive timing light up to a 12 VDC battery & use the induction pick up from the plug wire then run the saw and see how close to design the timing is.

The voltage "trigger" to the new chip must be delayed in sensing the coil's change of induced voltage to determining when to fire, since you had to advance the flywheel? The original trigger unit is at the top of the Bosch module like you had stated, about 180° out from the coil on this model.


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## Trigger-Time (Nov 4, 2010)

I do think you can get one set to close to TDC.
It may run it's best set that way but may burn a hole
in top of piston in time.

Doesn't the plate the coil mounts on adjust for timming
without needed to move flywheel.


TT


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## maico490 (Nov 4, 2010)

056 ignition systems were one of the few things I thought I knew something about but what you've done makes me think I still know nothing. Please can you get some pics up ( else it didn't happen  ) so we can all see what the fix is. I'm guessing that because of the mutiple magnets in the Bosch flywheel the ignition could be firing several times per revolution. This wouldn't neccessarily be a problem as modern ignition units will support very high revs and most small 4-strokes fire every rev as they get their trigger from the crank. Also agree with Trigger-Time about there being quite a bit of adjustment on the backplate.


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## blind hog (Nov 4, 2010)

I'm glad you mentioned 26 btdc, the preferred ignition timing was my next question! The reason I rotated the flywheel instead of adjusting the backplate was because I didn't know how much adjustment would be needed. I started by making big changes. after finding where the saw would run I did try adjusting the ignition plate. I adjusted to nearly full advance but the saw would not fire there. It is certainly possible that I just didn't go far enough. Yes I did take pictures, but I am computer challenged so I will have the wife help me put them on after dinner. I did run the saw today for about two hours; it ran great.


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## sefh3 (Nov 4, 2010)

I want to see pics of this. Read my signature line and it will help you with the pictures.


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## blind hog (Nov 4, 2010)

*Picture*

Here's a picture.


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## blind hog (Nov 4, 2010)

I guess I should have taken more pictures, but it seemed like a futile attempt until I got spark. I only have two pictures and they're both pretty much identical. As you can see it is VERY simple. I ordered a new module for it today, the module you see in the picture is in very rough shape. Since it works so well I don't mind spending 26.00 on it. If anyone would like I can take more pictures at that time. Let there be no doubt, this *DOES WORK.* Try it.


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## mountainlake (Nov 5, 2010)

Good going, I have a friend with the same problem. Steve


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## hotshot (Nov 5, 2010)

*Great Idea!*

Don't know why it would not make spark at any position, that part of your great experiment does'nt make sense. The magnets in the FW don't know where the coil is rotationally, just that it passes by to charge it. The trigger you installed then collapses it to fire the secondary side.

There is less than +/- 3° adjustment, or 6° total on that Bosch CD baseplate.

Sure would like to see it degreed while running, do you have an automotive timing light or need information on how to do it? I can tell you how to do it from the PTO side with the clutch carrier marked as reference, as doing it from the FW side is not "OSHA" approved (yanking the starter off while it's running) and keeping your fingers away from the spinning fins. Just takes a few seconds to shoot the marks while it's running about 6,00 RPM.

Probably have thrown a half dozen of those dam things in the trash....now I may be sorry. Same thing for the SEMs.


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## Trigger-Time (Nov 5, 2010)

blind hog said:


> Here's a picture.




Thanks for the Picture, this is my weak point when it comes
to chainsaw repair. I have 056 Super I put points in and a 056
thats waiting on a SEM FW and coil I picked up. But I think
I may try your repair on the Bosh setup and save the SEM
in case I ever find 056mag II 

This fix could make for some happy 056 owners 


Thanks,
TT


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## blind hog (Nov 5, 2010)

Yes hotshot, I do have a timing light. Thanks for the suggestions, but I think I,ll do the timing from the suiside. I'll remove the starter and fanwheel first and start it with a good cordless drill (after marking the flywheel). I did hook a digitron tach to it today. To my disbelief it displayed an idle rpm of about 2000 and high end of about 9400. I then hooked the tach to my 051 and showed about the same readings. This leads me to believe that it's just firing once every two cycles! Like maico490 said, looking at the flywheel you would think it would fire several times (I expected 4 times every two cycles). I'll do more research. Oh yeh I took pictures of the tachometer event if anybody wants to see them.


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## hotshot (Nov 5, 2010)

*Sounds fine*

Once per cycle sounds fine, as there's only one North magnet in the #0204 098 002 Bosch CDI flywheel, the other three are South. I'd like to know the approximate flywheel keyway to shaft key orientation when I come across the next dead Bosch.


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## NeoTree (Nov 5, 2010)

The 056 should turn 11,000 RPMs
056 Super - 11,500 RPMs
056 Mag II - 12,000 RPMs if memory serves me right
Average Idle speed should be 1,800 w/clutch engaging at 2,500
advance is adjustable from 26.2 to 27.5 degrees BTDC

My weakspot is ignition knowledge as well, so this will only work on the non-SEM equipped saws? I'm just waiting for the day my mag2's to stop. I absolutely love them big suckers. Running a ported one ain't bad either:hmm3grin2orange:

ps. Awesome info blind hog, you deserve mucho rep


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## sachsmo (Nov 7, 2010)

Rekon this would work on an old Sachs Dolmar with the Bosch ignition?


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## maico490 (Nov 8, 2010)

I've been away for a day or two so haven't kept up with this thread. All I can say is hats off to you blind hog. Even Lakeside said that modules won't work on a Bosch flywheel because of the 4 poles. From your rpm readings the module must be ignoring the 3 souths and only firing when the north pole passes which I suppose must have been what the Bosch electronics were doing originally. Maybe the aftermarket modules like the Nova and Atom don't differentiate between the poles.
I nearly threw out my Bosch flywheel and module the other day but it will be awaiting another 056 now.


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## blind hog (Nov 8, 2010)

I'd have to say that ignition is my week-point as well. I understand how the coil operates or at least the theory, but that module is full of fairy dust as far as I can tell. Most of the ignitions I have dealt with are either points or magnetic trigger. The way I fix the points ignitions is to install one of these modules. Its normally pretty simple, if the magneto is bad you just replace it. That wasn't an option here. I really didn't think this would work because of the flywheel design, but I thought it might lead me towards something that would work. Seems odd that it would ignore the south magnets and recognize only the north, but I'm not disappointed. I'm not familiar with the Sem ignition, the bosch ignition is modular so it was easy to isolate the coil. That Sachs coil certainly looks identical. As far as the flywheel indexing is concerned I'm going to slap a degree wheel on the pto side and find out just how many degrees I have advanced the flywheel. Right now I think the ignition timing is a hair slow. The saw never offers to tear your hand off like it occasionally use to. also the head temp stays pretty cool (maybe I should leave it alone) as I also had an under plug censor on it.


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## Justsaws (Nov 9, 2010)

Mega-Fire modules will work. I would recommend that the module be mount up near the rear handle instead of under the flywheel as they can be a tad temperamental with heat. 

I have yet to find a Bosch coil that they will not work with. 

It is a good solution to the ignition issues with the 1115 Stihls.

Lots of Bosch flywheels for the Mags.

The SEM modules can be done just more of PITA.


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## blind hog (Nov 10, 2010)

Good idea justsaws. I'll run a lead out with the plug-wire. Also makes it more serviceable.


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## sachsmo (Nov 10, 2010)

Good suff here,

Where do I find the mega fire?

Cheaper than $29?


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## sawslow (Jan 15, 2011)

*Timing?*

Did you check timing with timing light? And if you did does it chang as saw speeds up?


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## betterbuilt (Feb 16, 2011)

Has anyone else tried this yet?


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## sawhawg (Feb 16, 2011)

*Bosch ignition repair*

This is a brilliant idea,have been looking for a fix,figured the module could be rebuilt with conventional available components rather than just settling for the manufacturers "NLA"(Which is cheesy product support anyways)I wrote stihl #####ing about letting a winner like the 056 fade into obsolesence,they wrote back with a list of outfits specializing in obsolete saw parts....I bought a module and flywheel from ebay and fixed my ignition failure,but have been staring at my old module now since I found this fix,planning my next failure.....Your trigger is shown mounted 90 degrees from the ignition coil as opposed to the 180 degree original Bosch trigger mount,this doesn't make a difference?Is there a killswitch lead coming off that available trigger?Finally,the electronics you sawed off,must be the trigger you used houses all that now?Oh one more thing....the flywheel tweak you mention(half a keyway advance)is that necessary or can timing be adjusted by the slots in the backplate?


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## jkay2 (Oct 19, 2012)

I'm working on a late 70's 045AV and the keyway doesn't allow for any angular adjustment of the flywheel on the crankshaft. For those guys that made the keyway modification, how was it done?




******* said:


> This is a brilliant idea,have been looking for a fix,figured the module could be rebuilt with conventional available components rather than just settling for the manufacturers "NLA"(Which is cheesy product support anyways)I wrote stihl #####ing about letting a winner like the 056 fade into obsolesence,they wrote back with a list of outfits specializing in obsolete saw parts....I bought a module and flywheel from ebay and fixed my ignition failure,but have been staring at my old module now since I found this fix,planning my next failure.....Your trigger is shown mounted 90 degrees from the ignition coil as opposed to the 180 degree original Bosch trigger mount,this doesn't make a difference?Is there a killswitch lead coming off that available trigger?Finally,the electronics you sawed off,must be the trigger you used houses all that now?Oh one more thing....the flywheel tweak you mention(half a keyway advance)is that necessary or can timing be adjusted by the slots in the backplate?


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## tolman_paul (Oct 19, 2012)

Remove the key from the crankshaft and file or grind to 1/2 it's width. Re-assemble and rotate the flywheel to the desired location. If that doesn't give you enough adjustment, you can very carefully use an abrasive cutoff wheel the same dia. as the key and widen the key slot as required.


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## blind hog (Jan 15, 2013)

Sorry for not keeping up with things. I haven't put a timing light on it yet. Its still running like a champ though I think the timing is a little slow. I haven't even moved the module from under the flywheel. As for *******'s ?. Module position doesn't matter. You could leave it in the truck if you had a long enough wire I just choke the saw to kill it but you could just ground the trigger wire to kill it. Yes, all the fairy dust is in the module now. To reposition the flywheel I just removed the key. The key is really just for indexing purposes.


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## Rookie1 (Jan 15, 2013)

Ive copied what was done on this thread but I cut a slot in the timing plate and moved it rather than move the flywheel. I have some pics somewhere and wanted to start a thread but havent had time.:msp_smile:


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## blind hog (Jan 15, 2013)

Good idea. Everything work ok?


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## Rookie1 (Jan 15, 2013)

blind hog said:


> Good idea. Everything work ok?



Yes and no. I had to get a longer sparkplug wire. The powerhead ran ok then put together and lost spark. Had to take back apart to put new wire on. Havent put whole saw back together yet. Have some good pics but cant find.:msp_biggrin:


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## chrisrusche (Jan 20, 2013)

*pictures/instructions*

I was searching for a fix for my grandfather's 045av super and found this thread I love this idea instead of $150 replacement from Germany. If anyone has put together pics and instructions on the modification that would be great. Gramps is wanting to go cut wood with me this spring and I would like to get his saw running.


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## atpchas (Jan 30, 2013)

Another data point here. I have an 056 Magnum that runs for a few minutes until it gets warm and then it dies until it cools off. I installed a Nova II and immediately got spark. Had to advance the flywheel about the width of the key for the spark to produce fire. What this thread needs is an explanation even an electrical dummy like me can follow about how to get the flywheel rotated the "right" amount. Right now the saw runs well in the garage, but how it does in wood remains to be seen. I haven't noticed any sign of kickback when starting, so I'm guessing I didn't advance too much.

In the meantime, I just want to add a big "THANK YOU" to blind hog for finding and reporting this fix.


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## psuiewalsh (Apr 25, 2013)

I am in the process of trying this trick with an 045 and bosch coil. Is the chip positive grounded or negative grounded for this saw? I tried negative and no luck with spark.


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## atpchas (Apr 26, 2013)

psuiewalsh said:


> I am in the process of trying this trick with an 045 and bosch coil. Is the chip positive grounded or negative grounded for this saw? I tried negative and no luck with spark.



I've done this mod on two 056s so far. I just followed the directions that came with the chips - pretty sure they called for negative ground. I will say that on my first attempt, I thought that the chip wasn't working because I couldn't get any kind of hit when trying to start. Then I did what I should have done first - check for spark with the plug removed. There was plenty of spark so I figured the timing had to be diddled as outlined by blind hog. As soon as I did that, the saw fired up without difficulty. On the second saw, I immediately modified the timing and the saw started right away. Good luck!


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## psuiewalsh (Apr 26, 2013)

I will try that this weekend. Did you cut the flywheel key or slot the ignition mounting plate to mod the timing?


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## psuiewalsh (May 6, 2013)

Ran the 045 and it made 6 long cuts and died. I let it cool off for an hour and it started again. I wonder if the coil is bad. Even with the nova chip the spark will not jump a tester gap but i can see a weak spark. I was reading about a 041 coil in its place as I have the bosch flywheel. Any idea which 041 coil I need to get?


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## atpchas (May 6, 2013)

psuiewalsh said:


> I will try that this weekend. Did you cut the flywheel key or slot the ignition mounting plate to mod the timing?



Sorry I missed this earlier. I removed the key and rotated the flywheel CCW (advance) approximately one key width. I'm planning to bring these 056s to the GTG next month in hopes of getting a lesson in fine tuning timing mods like this.


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## Rookie1 (May 7, 2013)

psuiewalsh said:


> I will try that this weekend. Did you cut the flywheel key or slot the ignition mounting plate to mod the timing?



The 056 I did I slotted the ignition plate and had to get a longer sparkplug wire. I really was not comfortable with removing the key and advancing the flywheel on the crank.


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## psuiewalsh (May 7, 2013)

The saw did run fine when it was running with the flywheel 1 key width CCW. I just need to figure our what coil to use that is economical and if it is the coil or the trigger that is getting hot. I am leaning toward the coil as the spark is very weak even when cold. This is with a new plug wire , plug and wire clip.


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## jerdejong (Jul 3, 2013)

*trigger timing*

How do you even ball park the trigger placement with the flywheel having 4 magnets?


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## psuiewalsh (Jul 4, 2013)

There was an thread here about adv it 1/2 key. Magnets must not care. It ran until it gets hot.

Sent from my C771 using Tapatalk 2


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## blind hog (Dec 29, 2013)

well, I thought my 056 finally died today. It quit me in the woods the other day. Pulled the spark plug out of my 017 and still wouldn't run. Tore into it today, and the first thing i noticed was that it had weak spark. I never did move the ign module out from under the flywheel so i figured I'd go ahead and install the new ign module i bought for it 3 years ago lol. Couldn't remember all the eccentricities of the timing so i pulled up this old thread to look at my old fix. Moved the module into the carb house (the bolt that holds the back handle housing). Also hooked up kill switch. Re-installed flywheel one full keyway advanced as per atpchas's recommendation ( 1/2 keyway did seem retarded). Still would not start. Messed with timing, pulled exhaust, tried starting fluid, stomped around and cussed. Finally put ANOTHER spark plug in it and BANG! it fired right up. 1 cylinder + 1 bad plug = no happy. Much peppier with full key of advance (good call atpchas). Now I realize that I left some things out on my old fix. Back in the old go-cart racing days we advanced ignition timing with an "offset" key. When we started racing high rpm (10,000 +) briggs modifieds with super light flywheels, offset keys just wouldn't live. The solution was to pull the key out and "red loctite" the flywheel to the crank. Trust me, you won't "spin the flywheel if you loctite it. Flywheel keys don't hold the flywheel in place period. The tapered (interference) fit is what keeps the flywheel in place. the key simply assures that you re-install in the same position every time. In order to know where the crank keyway is when installing the flywheel I marked the end of the crank with a punch. Also, building a fw puller is super simple. Big bolt, big nut, welded to 3/8 steel ring and drill 3 holes. Long bolts from hardware store.


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## blind hog (Dec 29, 2013)

Oh yeah, psuiewalsh. "Getting hot and then dying" is very characteristic of a bad coil. I don't know anything about the "nova" chip. I do know that the "chip" is just a trigger, it adds nothing to the spark. It receives no power therefore creates no power.


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## psuiewalsh (Dec 30, 2013)

Nice. I ended up buying a parts saw and sold the saw a while after that. I still have the chip setup with a coil and flywheel though if you need.


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## sachsmo (Dec 30, 2013)

Several models of Sachs Dolmar use that Bosch ignition.

On the SDs the mounting plate is slotted, super easy to advance timing, but you will know if'n you go too far!


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## dieselpilot (Mar 7, 2014)

blind hog said:


> Recently solved my Stihl 056 Bosch ignition problem. After visiting this and other websites looking for answers to the "it runs for about 20 minutes and then dies" problem, I discovered many people having the same issue. My saw finally quit firing at all. I'm sure someone has already posted this solution but i haven't seen it. It's fairly obvious that the bottom (detachable) portion of the ignition unit is the coil. Cut the jumper wire from the coil to the (epoxy filled) electronics, solder this lead to a 1118-400-1001 trigger unit lead (26.00 from stihl dealer), ground the module, and the ignition will fire, assuming that the coil itself is not the issue but rather the electronics. Strangely enough the saw still would not fire. Blaming the lack of combustion on ignition timing, I pulled the key out of the crankshaft and began rotating the flywheel a few degrees in either direction. Retarding the flywheel (clockwise) about half a keyway created the desired response. I undoubtedly need to fine tune the ignition timing, but the saw runs perfectly. I then removed the top (detachable) bosch trigger unit and bandsawed off the (epoxy filled) electronics in order to mount the new trigger unit properly.


The pictures of this mod aren't accessible anymore. Does anyone have any pictures of a modded ignition unit ? Thanks!!


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## blind hog (Mar 10, 2014)

They should be on my old phone. I'll try to find them.


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## dieselpilot (Mar 10, 2014)

blind hog said:


> They should be on my old phone. I'll try to find them.


Thanks very much! I have 2 045s and 2 056s so this mod will be essential for me in the future, as I love and use these saws. Thanks again.


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## blind hog (Mar 12, 2014)

Here they are.


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## Mastermind (Mar 12, 2014)

Good stuffs.....


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## dieselpilot (Mar 12, 2014)

Perfect! Thanks very much!! I was having a hard time visualizing the final product.


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## Trzebs13 (Mar 12, 2014)

Has any one else got this to work? I tried it with 2 different coils and no spark.


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## rickyrooster (Mar 13, 2014)

If this fix works well this should be made into a sticky. The 056 stihls down fall is the ignition. Being able to get them up and running again is priceless. Rick!


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## blind hog (Mar 17, 2014)

I have moved the module into the carb compartment since these pictures where taken. Fix works great and is simple. The trick is to advance the flywheel one key-width (counter clockwise). Just remove the key and rotate until the side of the flywheel keyway is even with the opposite side of the crank keyway. Tighten it down and dont worry about it. If the problem with the ignition is the coil then of course the fix is useless. I have seen a thread on this forum in which you can get a replacement ignition for these saws. Looks like it comes from germany and sells for 125.00. Sells on ebay from seller saegenspezi. The guy said he installed it and it fired right up. Hasn't cut with it yet. Looks sort of like what I ended up with if I would have put the trigger module in shrink tube.


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## dieselpilot (Mar 19, 2014)

blind hog said:


> I have moved the module into the carb compartment since these pictures where taken. Fix works great and is simple. The trick is to advance the flywheel one key-width (counter clockwise). Just remove the key and rotate until the side of the flywheel keyway is even with the opposite side of the crank keyway. Tighten it down and dont worry about it. If the problem with the ignition is the coil then of course the fix is useless. I have seen a thread on this forum in which you can get a replacement ignition for these saws. Looks like it comes from germany and sells for 125.00. Sells on ebay from seller saegenspezi. The guy said he installed it and it fired right up. Hasn't cut with it yet. Looks sort of like what I ended up with if I would have put the trigger module in shrink tube.


Just to keep this outstanding thread fully documented, could you post some pics of the setup as it exists today? The more detailed and plentiful the pictures the better!!!


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## Trzebs13 (Mar 19, 2014)

Would this be along the same theory?

http://cgi.ebay.com/ws/eBayISAPI.dl...akeTrack=true&ssPageName=VIP:watchlink:top:en



I dug the one out that I tried and noticed that the trigger unit I got looks different than yours. Maybe what it my issue.


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## trappermike (Mar 20, 2014)

I our shop in the 80's another mechanic and I ended up doing the same thing to an 056 to see if it would work,repair a $200 Bosch ignition with a $7 aftermarket part sold as Atom or Minitron-a little electronic module like the ones you are using.We hacksawed off the electronics in epoxy part and wired in the module,we didn't do anything with the timing and we got good spark,We were jubilant and had a cheap repair for the Bosch ignition so we repaired a few 056's that way.
The problem for us was they all soon died,especially after a faller raised hell on the phone,I had to drive in the shop truck 2 hours north in winter to the little town he was working from and install a new Bosch ign. at our expense, and I had to do the job on the shop's concrete floor not the workbench because he was mad. The Boss banned us doing that anymore.Another shop had been doing the same thing in Gorman-Rupp pumps and the little modules replaced an expensive ignition,but they all soon failed for him too after a while.
In the end we concluded this;
-The little electronic modules work great in most cases-Where the flywheel has it's magnets located in just one spot on the flywheel's circumference.
-The electronic modules will fire well but die after a short while when the flywheel of the ignition involved has magnets located all around it's circumference.(Like a Bosch type on 056)
I also back then put one of the little units on my friend's kid's Yamaha 80,replacing the points,it sparked well and ran great,but a week or 2 later it was dead,no spark,and it's flywheel had magnets all the way around.
I'm not trying to rain on your parade or anything and I'm hoping the newer models now have better electronics and your Bosch fixes will be good.I've got a new one to install in my old 275 Canadien.
But maybe just be cautious and see how the first few work out and note what type flywheel the motor has when contemplating installation...


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## dieselpilot (Mar 20, 2014)

trappermike said:


> I our shop in the 80's another mechanic and I ended up doing the same thing to an 056 to see if it would work,repair a $200 Bosch ignition with a $7 aftermarket part sold as Atom or Minitron-a little electronic module like the ones you are using.We hacksawed off the electronics in epoxy part and wired in the module,we didn't do anything with the timing and we got good spark,We were jubilant and had a cheap repair for the Bosch ignition so we repaired a few 056's that way.
> The problem for us was they all soon died,especially after a faller raised hell on the phone,I had to drive in the shop truck 2 hours north in winter to the little town he was working from and install a new Bosch ign. at our expense, and I had to do the job on the shop's concrete floor not the workbench because he was mad. The Boss banned us doing that anymore.Another shop had been doing the same thing in Gorman-Rupp pumps and the little modules replaced an expensive ignition,but they all soon failed for him too after a while.
> In the end we concluded this;
> -The little electronic modules work great in most cases-Where the flywheel has it's magnets located in just one spot on the flywheel's circumference.
> ...


Blind Hog moved his trigger module into the carb box and away from the flywheel magnets (a pic would be helpful ). Apparently, he didn`t have a problem before he moved it. He is using a quality Stihl part (1118 400 1001) which may help.


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## blind hog (Mar 20, 2014)

Luckily I'm not trying to when any prizes or popularity contests. This repair has worked for me for nearly three years. The 056 is my primary saw. I farm over 1000 acres and heat exclusively with wood. Just trying to give an idea of frequency of use. I can't imagine that the magneto would fail due to a different trigger being used. Magnetos tend to be EXTREMELY durable. By changing the trigger (module) the magnetos environment hasn't been changed. It is still being charged by the same magnets. The trigger simply interrupts the flow of current through the primary coil causing the voltage spike. I guess the wild card here is the multiple magnets as trappermike said. I'm not sure why there are so many unless it has something to do with either the shape of the armature (not shaped like a 'U') or recovery time. In any case I was very surprised to see that little module live for two years under the flywheel. Normally I try to locate them somewhere much kinder but I didnt really expect this thing to work in the first place. As stated above I have replaced the original module that I used. Not because it quit working but rather because it was falling apart. Lots of vibration and harmonics under that flywheel I'd say. I'll get new pictures up asap.


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## blind hog (Mar 20, 2014)

Oh yeah. It seems like someone else tried this with a different brand of trigger and it wouldn't work at all. Maybe their magneto (which I've been calling a coil up till now) was bad or maybe there is a difference in the sensitivity of the modules? That looks perfect to me Trzebs13.


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## trappermike (Mar 21, 2014)

The magneto didn't fail the aftermarket triggers did,on magnetos with a "full magnet" flywheel. But maybe now the newer trigger modules are better and they won't fail in those apps. I used the jobber trigger in a lot of different motors and they worked great,I hope they work now in the 056. I used the Stihl module too with good success.


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## dieselpilot (Apr 3, 2014)

If you get a chance, final configuration pictures would be much appreciated!!!


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## foggysail (Apr 6, 2014)

Very interesting thread! There are things I don't understand though. For example what problem is being solved, the high voltage coil opening up or the control module. Adding a trigger unit just replaces the control circuitry and has ziltch to do with the high voltage transformer heating problem. Next, I don't know how those trigger modules function. Those in the Bosch ignition use a separate coil from the high voltage circuit to provide the stored energy that gets dumped by the thyristor into the high voltage transformer. But if it works ... it works. You cannot ******** physics. OH and EBay sells those trigger units now for big bucks... over $50 each.

Obviously I share the same woos with my Bosch ignition used in my 056. I just took a chance and ordered the high voltage transformer for a TS350 (thanks to getting info here in the forums) and intend to give it a try. If the mechanics are different than what I now have, well then it will not work. But for $30 delivered from EBay I thought it is worth a shot. 

General comment! Electronic designs for circuits such as those Bosch used in the 056 and others should have had a better reliability analysis before they were implemented into chainsaws. There is no black magic here but there is poor electrical engineering that all owners of those early saw designs now suffer with while trying to keep an old work horse functioning.

Foggy


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## foggysail (Apr 7, 2014)

A follow up to my post above. I ripped apart my 056 ignition's control section this afternoon. I do not think the fault with these things is related to the magnetics because I found the charging capacitor in this jewel of mine SHORTED! The value is 0.8 microfarad rated at 400 V. Tough to get at, had to remove all the potting material. This is the capacitor that stores the energy to transfer to the high voltage transformer via an SCR (thyristor). But it looks like the ignition system can also work as a magneto as others are successfully getting it to work with just a trigger module.

This would explain why others have had such great results changing just the control circuit. So today I ordered a Kawasaki 31-9334 which cost about $20 including shipping. I would reassemble the ignition I ripped apart to test it but I don't have many capacitors in my collection. If I find one before I build in the Kawasaki, I will give it a try. I am NOT going to mount it inside the existing ignition but rather somewhere where it is cooler and just run wires back to the transformer under the flywheel.

Back to today's find, the capacitor's physical size is interesting. It resembles a half drum sliced vertically with that length around an inch. It is about 075" wide and about 5/8" high. What makes these dimensions interesting is they are VERY small for the capacitance value while rated at 400 V. One way that can be done is to make it with a mylar dielectric. But if it is made using mylar, there is a major shortcoming at least for this particular application. Metal film Mylar that I have seen are only rated for 85 degrees C (185 degrees F). The control module is in a very hot environment so my guess is this part is the culprit and not the coils. But remember, I am sampling a quantity of one.

Just thought I would share what I found.

Foggy


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## DIYDoug (Aug 21, 2014)

I'm bought some capacitors to fix my ignition module. Somewhere I came across these, which are 400v, 0.82 uF. Other links point to a 1.0 uF. Will this .82uF work?
http://www.ebay.com/itm/310579397823


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## Rx7man (Aug 22, 2015)

They're more money ($7 each) than the Ebay ones, (perhaps better quality?), and you can get them in different ratings... just thought I'd post of another place you can source them
http://ca.mouser.com/ProductDetail/...=sGAEpiMZZMv1cc3ydrPrF6b39BhxIu4vTPelFB1kQag=


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## POC (Apr 2, 2016)

Should this work for a 056 Av Electronic?

Sent from my SAMSUNG-SM-G870A using Tapatalk


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## foggysail (Apr 2, 2016)

POC said:


> Should this work for a 056 Av Electronic?
> 
> Sent from my SAMSUNG-SM-G870A using Tapatalk



It will work if it's the same ignition that I analyzed and provided repair instructions. Please see:

SUCCESS!!! Just repaired Stihl 045/056 Bosch electronic ignition!!!!! - 

http://www.arboristsite.com/communi...ihl-045-056-bosch-electronic-ignition.256095/


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## POC (Apr 2, 2016)

foggysail said:


> It will work if it's the same ignition that I analyzed and provided repair instructions. Please see:
> 
> SUCCESS!!! Just repaired Stihl 045/056 Bosch electronic ignition!!!!! -
> 
> http://www.arboristsite.com/communi...ihl-045-056-bosch-electronic-ignition.256095/


I've found that in the mean time, thanks. 

Sent from my SAMSUNG-SM-G870A using Tapatalk


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## foggysail (Apr 2, 2016)

POC said:


> I've found that in the mean time, thanks.
> 
> Sent from my SAMSUNG-SM-G870A using Tapatalk




Good luck!!! Remember it's not rocket science, others have implemented it with good success with no electronic background and you will be able to also..


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## yellowhair (Nov 19, 2016)

I just traded for a good looking 056 av super and found no spark. I was reading this link (googled and found same) before joining and found it most interesting - thus the reason that I joined. I don't know much about these older Stihl saws, but I do work on a lot of the smaller saws - everything from Stihl to Poulans - I'm retired and find the work relaxing and informative. Anyway, when I took the flywheel off the saw I found a Bosch magneto stamped as such with Stihl number 0204 098 006, underneath the flywheel and magneto package is what I believe to be an SEM ignition (it has the name Selettra stamped on the underside) with the number 1108 400 0804 A. I have read some discussions about 3 types of ignition packages but find it hard to believe that these two would be intermixed. Does it appear to you, as to me, that someone has mismatched the parts? Thanks for any input.


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## trappermike (Nov 23, 2016)

So did you actually affirm how mant degrees before TDC is it firing now?


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## trappermike (Nov 23, 2016)

We tried those in the 80's but they died or fired way out of time. Put a timing light on it and see...


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## trappermike (Nov 23, 2016)

They work great with most ignitions but I'm not sure of 056.


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## trappermike (Nov 23, 2016)

Well at the time we did it with a guys falling saw and it came back in a week dead. The guy had a stuttering problem and called the mechanic a c-c-c-**********,he was mad,so we stuck an original ignition back in it. Then the next one died,I had to traval a 100 miles in arctic winter to some tiny place,I just stuck a new one and went ..
I'm not convinced these trick little units work on a system with magnets all around the flywheel.


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## trappermike (Nov 23, 2016)

They seem to work great on other ordinary ignitions,specially where the magnet is in one place on the flywheel. My next antique hotsaw has one...


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## nolids (Jul 7, 2018)

Just joined up to share my Sachs Dolmar 133 story. I got the free saw complete and it looked hardly used. After rebuilding the carb I could get it to start, but only run for a few seconds. Then it would not start unless I waited 24hrs. So this went on quite a few times with me thinking it was the rebuilt carb not adjusted right. Then one morning I got it to start, and actually stay running at high throttle for maybe a minute while cutting a log. Then it slowly lost power and died. No start.
I finally figured out it had to be the ignition. So I started swapping coils and that didn't work so I figured it must be the module. A Nova2 didn't help, and I had the hardest module to find-- a SEM GE! No replacement to be found. This is 2018 and parts are getting harder to find than when this topic was started years ago.
I had been reading the chainsaw boards and found the link for the German complete module and coil that said it was for a Dolmar 133. Great! I also found a Bosch flywheel to go with it. So after waiting a couple of weeks I got the parts and put them in. I checked the timing with a timing gun and it was something like 32 degrees AFTER top dead center. I figured that the Sachs Dolmar 133 and the Dolmar 133 ignitions had to be different. 
Now what? I decided to drill new adjusting holes in the backing plate. One of them had to be right next to the coil. That took it to just after TDC. I needed 26 degrees BTDC. So I used the top mounting screw that held the coil on and tapped it out to the same threads as the hole for the mounting plate and it was aligned perfect for a longer screw that held the top of the coil to the base plate and moved the base plate counter-clock wise screwed down.
Guess what? I checked timing and it was now 26 degrees BTDC and the chainsaw started with a roar with just one pull! That was at quiting time last night so I'll see what happens today. I can never tell, this saga has been going on for months.


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## Rx7man (Jul 7, 2018)

Another option would be to run the flywheel keyless and advance it... I found the trick to that is to make a mark on the flywheel approximately where it fires in relation to the coil (or case, if you have a coil that's under the flywheel), then, run it with a timing light and mark the case where it lines up with the mark on the flywheel. After that, remove the key, move piston to desired firing position and retighten the flywheel... Might be handy in other cases, glad you got it to work though!


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## nolids (Jul 7, 2018)

Rx7man said:


> Another option would be to run the flywheel keyless and advance it... I found the trick to that is to make a mark on the flywheel approximately where it fires in relation to the coil (or case, if you have a coil that's under the flywheel), then, run it with a timing light and mark the case where it lines up with the mark on the flywheel. After that, remove the key, move piston to desired firing position and retighten the flywheel... Might be handy in other cases, glad you got it to work though!



I tried changing the flywheel position and it didn't change the timing. Then I realized that only works with an outside coil. I am getting great spark now, but the carb isn't working quite right so keeping it running when cold is a trick.


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## hotshot (Jul 7, 2018)

nolids said:


> I tried changing the flywheel position and it didn't change the timing.



What? It has to change the static timing.

It makes no difference if the stator sets inside the flywheel/rotor, or outside. Moving the stator in the direction of flywheel (FW) rotation retards it, opposite the FW rotation advances.

Saw engines rotate CCW on the FW side (most do...)

So just the opposite, rotating a keyless FW CCW on the shaft taper advances the timing.

Are you using an old school timing light, a 12vdc battery, and a paper timing wheel for your timing check?


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## nolids (Jul 7, 2018)

Of course-- 12v battery and pick up clamped to the spark plug wire on the saw. You HAVE to move the base plate and coil to change timing. I have a four magnet Bosch flywheel. And it has north/south magnets to trigger the coil. Moving the flywheel only made the timing light dimmer, it did not change when the spark occurred.


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## hotshot (Jul 7, 2018)

Ok, good luck with it.

It sounds like you’ve bought a German Sagenspezi replacement for the Bosch CD/coil stator there.


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## nolids (Jul 7, 2018)

Yes, the electronic Saegenspezi they sell on German eBay for a Dolmar 133.

How about some starting tips for this beast? Pull two times with choke closed and open throttle locked on, then turn on switch, position choke to half, and it is supposed to cold start? Or is there a better method for cold starts? I have a problem doing this because the 133 stalls when I give it gas then doesn't want to start again. I get tired pulling the rope.


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## hotshot (Jul 7, 2018)

Start a new thread on that.

Call it cold starting a Dolly 133, or whatever you want. 

You need to pull it & listen/hear the saw burp or briefly start with it set on full choke, then flip the choke off. 

It may take a half dozen pulls or more on a dry carb to get fuel up into it.


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## nolids (Jul 8, 2018)

I'm not having good luck today. I tried to start the 133 and choked it then unchoked it flipped the switch on and spent good 5-10 minutes and not even a kick! So rechecked with timing light, still the same 26 BTDC. Spark plug had a thin light when tested, didn't look strong.

So I checked the plug using my electric start Honda 5.5 engine and got a blinding flash off the NGK plug holding it against a ground. It's funny when I was playing with the chainsaw timing before, it was starting with the easiest pull and the timing was wrong. Now it is right and the bastard won't start! Well, it did start once, but the flywheel nut was not tight and I broke the woodruff key, but that shouldn't have hurt anything.

Tell me something...


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## nolids (Jul 8, 2018)

I just thought of something-- I need to retime the flywheel to he new coil timing position. They work as a pair.


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## nolids (Jul 8, 2018)

Retimed/repositioned flywheel (C C 44mm) and she fired up and ran great. This baby has some power! Just need to get the carb dialed in.

Picture shows oval hole normally used for mounting screw, mounting screw now holds the coil. 44mm difference.


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## nolids (May 4, 2019)

nolids said:


> Retimed/repositioned flywheel (C C 44mm) and she fired up and ran great. This baby has some power! Just need to get the carb dialed in.
> 
> Picture shows oval hole normally used for mounting screw, mounting screw now holds the coil. 44mm difference.View attachment 661909


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## nolids (May 4, 2019)

Thought I would give an update on my Sachs Dolmar 133 ignition replacement. The last few posts explained how I got my saw running using the German ignition replacement. However, it worked for awhile then quit. So I put it aside until this spring when I needed to cut wood for next winter.

So when I tried to get it going recently, it would start and then quickly die, then not fire at all. Just like it did when I got it with the original SEM GE ignition.

So after several tests, I determined that the ignition module was the problem. I put a Nova 2 and it fired right up and ran for 5 minutes and died. WTF. I did a Google search and finally found a Homelite chainsaw forum that people were having the same problem with Nova 2's mounted INSIDE the flywheel, and that the solution was to mount the ignition module out and away from the heat.

So I got another Nova (a newer version) and mounted it next to the carb so the only thing inside the flywheel is the coil, and ran the wires to the kill switch.

I just did a 20 minute cutting test and the saw ran perfectly. HTH


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## nolids (Jan 7, 2020)

nolids said:


> Thought I would give an update on my Sachs Dolmar 133 ignition replacement. The last few posts explained how I got my saw running using the German ignition replacement. However, it worked for awhile then quit. So I put it aside until this spring when I needed to cut wood for next winter.
> 
> So when I tried to get it going recently, it would start and then quickly die, then not fire at all. Just like it did when I got it with the original SEM GE ignition.
> 
> ...


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## nolids (Jan 7, 2020)

A couple of more insights into upgrading from the SEM GE to an ignition module Nova2. If you don't want to buy a Bosch type flywheel with the magnets (N-South) 180 degrees apart, you can get your 4 magnet SEM GE to work. Only two of the sem magnets are magnetic, the other two are non-magnetic and are only for balancing the flywheel.

Using a propane torch, remove the south magnet and screws, and remove the dummy .agnet


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## DIYDoug (Jul 22, 2020)

I just came across a good video from Yankee Nimrod , which shows how he applied the Stihl 056 AV ignition coil fix (adding a capacitor). I could use some help on two items:
1. What size capacitor is used? (I see info earlier in this thread, but couldn't find that exact one online)
2. The kill switch wire was cut and glued-over in the video. What is the purpose of cutting the kill wire, and how is the kill switch functionality restored?
Thank you in advance for your insight.


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## j-jock (Aug 13, 2020)

DIYDoug said:


> I just came across a good video from Yankee Nimrod , which shows how he applied the Stihl 056 AV ignition coil fix (adding a capacitor). I could use some help on two items:
> 1. What size capacitor is used? (I see info earlier in this thread, but couldn't find that exact one online)
> 2. The kill switch wire was cut and glued-over in the video. What is the purpose of cutting the kill wire, and how is the kill switch functionality restored?
> Thank you in advance for your insight.



The capacitor required is called a run capacitor.
The specs are: 0.8 micro farad, 450 volt, metallized polypropylene metal film capacitors.
They sell for approximately $10.00, depending on the seller and the number of pieces you purchase.

I almost forgot to add:
The best way to increase the life and the reliability of this unit, is to run the wire out from under the flywheel, and mount it on the outside of the flywheel. One person that was experimenting with these caps, stated that they do get hot, and do better with lots of air circulating to keep it cool.
Bob


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## charmon23 (Dec 8, 2020)

foggysail said:


> Very interesting thread! There are things I don't understand though. For example what problem is being solved, the high voltage coil opening up or the control module. Adding a trigger unit just replaces the control circuitry and has ziltch to do with the high voltage transformer heating problem. Next, I don't know how those trigger modules function. Those in the Bosch ignition use a separate coil from the high voltage circuit to provide the stored energy that gets dumped by the thyristor into the high voltage transformer. But if it works ... it works. You cannot ******** physics. OH and EBay sells those trigger units now for big bucks... over $50 each.
> 
> Obviously I share the same woos with my Bosch ignition used in my 056. I just took a chance and ordered the high voltage transformer for a TS350 (thanks to getting info here in the forums) and intend to give it a try. If the mechanics are different than what I now have, well then it will not work. But for $30 delivered from EBay I thought it is worth a shot.
> 
> ...


Hi Foggy,
I have an 056 that has a bosch flywheel. The person that owned it before had an aftermarket module which will not work. How can I get this saw running again. 301-674-6267 Thank you Chris Harmon Ft Valley Va


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## charmon23 (Dec 8, 2020)

DIYDoug said:


> I just came across a good video from Yankee Nimrod , which shows how he applied the Stihl 056 AV ignition coil fix (adding a capacitor). I could use some help on two items:
> 1. What size capacitor is used? (I see info earlier in this thread, but couldn't find that exact one online)
> 2. The kill switch wire was cut and glued-over in the video. What is the purpose of cutting the kill wire, and how is the kill switch functionality restored?
> Thank you in advance for your insight.


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## charmon23 (Dec 8, 2020)

Doug were you able to make this repair?


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## DIYDoug (Dec 13, 2020)

charmon23 said:


> Doug were you able to make this repair?


Charmon23, I tried to repair, and could not get the cover off of the ignition coil. My home-made puller tool worked the first time (about 5 years ago), but this time it was so stuck that the holes were starting to strip when I tightened down the tool. After much thought, I chose to sell it in "not working" condition. I sold it to someone who is confident that he can get it working. I sure hope he get it going, as it is a powerful saw that should last a lot longer.


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## DIYDoug (Dec 13, 2020)

j-jock said:


> The capacitor required is called a run capacitor.
> The specs are: 0.8 micro farad, 450 volt, metallized polypropylene metal film capacitors.
> They sell for approximately $10.00, depending on the seller and the number of pieces you purchase.
> 
> ...


Charmon23, I just saw your questions from earlier. Above is info on the capacitor. I found one that met these specs at mouser.com. Here's one that I ordered. It's not the exact specs, but they have a variety to choose from. https://www.mouser.com/ProductDetai...YAJq/JVLvew==&countrycode=US&currencycode=USD
You also asked why the person cut the kill switch, and how the kill switch functionality was restored. I commented on the video and he replied that he uses the choke to kill the engine. I would prefer to restore the kill switch functionality. Perhaps the original wire could be used, and just heat-shrink covered so it doesn't short-out against the engine.


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## charmon23 (Dec 14, 2020)

DIYDoug said:


> Charmon23, I just saw your questions from earlier. Above is info on the capacitor. I found one that met these specs at mouser.com. Here's one that I ordered. It's not the exact specs, but they have a variety to choose from. https://www.mouser.com/ProductDetail/kemet/r75mr4100aa40k/?qs=uwUAEbwHiLeYAJq/JVLvew==&countrycode=US&currencycode=USD
> You also asked why the person cut the kill switch, and how the kill switch functionality was restored. I commented on the video and he replied that he uses the choke to kill the engine. I would prefer to restore the kill switch functionality. Perhaps the original wire could be used, and just heat-shrink covered so it doesn't short-out against the engine.


Doug,
Thanks so much I think I got this all figured out now waiting for the part
Merry Christmas 
Chris


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