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

[tntatro]

I've tried five or six fixes since discovering this thread and about half took the fix. For the ones that did not work I used a Nova II module or similar and advanced the flywheel and now have a 100% success for fixing them one way or another.

It took a bit of tinkering to get the Nova fix figured out because I had many used parts giving me troubles such as carburetors and weak clutch springs. After figuring out it was the worn out parts and not the ignition I've been having good luck with ignitions. Not so good luck selling these saws though.

 

[foggysail]

This little guy would not revive with "The Fix". I cut the PC bus just like the pics, and my previous two modules, but no sparky.

I even cut off the kill wire to eliminate that variable, but all I can get is a weak pulse on the high side while holding onto the lead.

Does the pulse means the Darlington SCR is working? The coil ohmed fine on both the primary & secondary sides.

So I've tried three now, the first fix did great, but I went downhill from there.

View attachment 575110 View attachment 575111

Hotshot-- not sure what is causing your problem. The spark intensity is determined by the amount of energy stored in the capacitor but having even a weak spark indicates that the scr is discharging stored energy. The amount of energy that the capacitor receives is determined by the rotating magnets. Is there any damage to the woodruff key....such as a small bend?

A lawn mower that hits a rock commonly has a starting problem after such events because the woodruff key gets bent which changes where the magnets are in relation to the firing. But I think this only happens with ignition point systems. I am guessing here........ if you have another capacitor, try swapping it and be sure the value is 1 uf, 0.8 does work but the larger cap provides greater spark energy. Your soldering looks fine.....but try reheating it anyway.

REmember there are many components in the ignition and any one of the can prevent proper operation. The internal capacitor however has shown to have a high failure rate.

Before you do anything, try swapping the capacitor or double up by using two of them in parallel.

 

[hotshot]

Thanks, yes something else in the circuit on this one is faulty, but it looks brand new! Will try 2 in parallel first, those will add like resistors in series.

Then I'm going to tap into the coil primary grey hot wire with a Stihl 11184001001 module routed to ground & see what happens. I will leave the new capacitor (or two) in the circuit.

Like I need to find place for another wire coming come out, LOL. I'll post back on the results.

 

[foggysail]

There are two reasons for having a series resistor in the coil circuit......... The first use of a resistor which was in the primary of the high voltage transformer..ie spark coil was to allow a car's coil to have maximum voltage during starting. When the engine was starting, the resistor was shorted out to compensate of the battery voltage drop while the starter was being operated. After the engine starts, the resistor was again in series with the transformer That was important with older 6 volt systems. Not sure if they still use this approach. I want to emphasize that older car ignitions used a flyback technique where as today...and teh saw.... they just transform the voltage to the secondary via the transformer's turns ratio.

The next reason was to damp out oscillations in the spark wire connected to the plugs. In fact today all spark plug wires have a carbon conductor that carries the energy to the plugs. This damps out those oscillations which could cause multiple firings.

So back to the saw. I doubt a resistor in series with the spark wire will hurt, but the voltage is so high it most likely will require a resistor rated for high voltage. Now if you put a resistor in series with the capacitor you will increase the time it takes for the capacitor to discharge...governed by the time constant which is the resistor value multiplied by the capacitor value. Also the circuit will behave as two resistors in series, the first will be the impedance (think resistance) looking into the primary of the transformer and the second with be whatever value you use in series. THIS WILL LOWER THE VOLTAGE ACROSS THE TRANSFORMER PRIMARY and result in a lower spark voltage.

 

[chief56]

detailed repair instructions along with clear pictures sure would be appreciated!!!! and much needed ..don't worry about ugly pictures. what's more important is explaining what needs to be replaced/fixed.

I've got a dead coil to send ... start conversation if you want it for a test Guinea pig

hoiw did your saw

A long post! I want to emphasize what I said in an earlier post, NO TIMING CHANGES ARE NEEDED............PERIOD!

I am not running a home laboratory to do failure analysis so the exact reasons for the Bosch capacitor failure is best asked to Bosch, not me and that includes what dielectric is used in their capacitor. And no, an electrolytic capacitor is out of the question for this application. The dielectric of my suggested capacitor is AC & pulse rated metalized film polypropylene.

how did your saw repair work out ? where can i get these capacitors ? thanks

 

[UmpquaMichael]

It worked for me. This is my first post. I have read a lot though. I am just getting into the fun. The first saw I have tried to repair and it actually worked. I didn't doubt your abilities. Just my own. I have a Stihl 056, a Husqvarna 272xp, and 2 Husqvarna 2100's.
The roar when it fired up put a light in my eyes and a smile on my face. Now to see how it does in the extended version. Thanks for figuring this out. I don't know if you still look at this thread, but I really appreciate it.

 

[paul99]

I tried this fix with my old Dolmar 152 a few weeks back (it uses the same Bosch ignition) but in my case it didn't quite work. I say quiet because although it did result in a spark where there was previously none it was too weak to start the saw. After a bit of time double checking everything with no improvement I opted for the ignition chip fix. I couldn't get hold of a NovaII quickly here in the UK but a cheap single leg unversal ignition chip (sig01) and timing advance later and the saw runs.

I'd always try this capacitor fix first though as if it isn't successful (and going by this thread you're unlucky if it doesn't) you already have the wiring in place to install the chip externally - clipping and moving the wire you soldered to the track to the coil input wire instead takes only a few minutes and the earth wire remains the same and is required also.

Thanks to foggysail for the fix, although it didn't quite work for me this time around I'm sure it will at some point in the future.

 

[hotshot]

Any pictures taken of the tap locations?

So on the Dolmar 152, you re-soldered/repaired the cut PC bus and returned to the original capacitor?

Why not leave it in & do both?, i.e. the new cap and new chip.

 

[paul99]

Any pictures taken of the tap locations?

So on the Dolmar 152, you re-soldered/repaired the cut PC bus and returned to the original capacitor?

Why not leave it in & do both?, i.e. the new cap and new chip.

I performed the foggysail fix as per his photos - that was not successful so essentially followed the fix shown here:
https://www.smokstak.com/forum/showthread.php?t=156427

Instead of cutting the module off the stator plate as per those photos I mounted the ignition chip under the top cover using the wiring I had already added for the foggysail fix.

Using the ignition chip does away with the whole trigger half of the orginal bosch module as such the external capacitor added for the foggysail fix is completely redundant so no need to repair the cut pc bus either.

Hope that helps
Paul

 

[PogoInTheWoods]

Good posts. Thanks for sharing your experience and that link. I wonder how many foggy fixes have failed due to a 'close enough in value' substitute capacitor being used instead of the one originally recommended? Different ones seem to have been tried with mixed results.

I have an 056 project in the wings with a bad SEM ignition and have been following this thread with great interest from the beginning in hopes of coming across a Bosch ignition and flywheel setup. Well, I finally found one..., only forty minutes away from me for $20! Now comes the fun if I can locate one of the correct capacitors. I'll certainly report the results here when I find the time to dive into the project. The saw is filthy and needs a tear down and cleaning before anything else. Who knows what else I may find under the crud, though the piston looks pristine through the exhaust port. I have all of $55 into it so far including the Bosch ignition and flywheel so it'll be a worthwhile project however it turns out. At least it'll be clean!

 

[paul99]

Good posts. Thanks for sharing your experience and that link. I wonder how many foggy fixes have failed due to a 'close enough in value' substitute capacitor being used instead of the one originally recommended? Different ones seem to have been tried with mixed results.

I have an 056 project in the wings with a bad SEM ignition and have been following this thread with great interest from the beginning in hopes of coming across a Bosch ignition and flywheel setup. Well, I finally found one..., only forty minutes away from me for $20! Now comes the fun if I can locate one of the correct capacitors. I'll certainly report the results here when I find the time to dive into the project. The saw is filthy and needs a tear down and cleaning before anything else. Who knows what else I may find under the crud, though the piston looks pristine through the exhaust port. I have all of $55 into it so far including the Bosch ignition and flywheel so it'll be a worthwhile project however it turns out. At least it'll be clean!

I suspect in those cases where this fix fails it's not a case of the capacitor value only being close enough but much more likely that any one of the other vintage electrical components in the module that has failed in addition to / instead of the capacitor.

Luckily you get a second chance of success with a Nova II / universal ignition module and I've yet to read about anyone failing with both fixes.

There is also a third option but it's by far most expensive option and that's a direct replacement module sold by Saegenspezi: http://m.ebay.co.uk/itm/190590733267?_mwBanner=1 which I believe are based on a universal ignition module and coil on a purpose made plate.

 

[hotshot]

I suspect in those cases where this fix fails it's not a case of the capacitor value only being close enough but much more likely that any one of the other vintage electrical components in the module that has failed in addition to / instead of the capacitor.

Luckily you get a second chance of success with a Nova II / universal ignition module and I've yet to read about anyone failing with both fixes.

There is also a third option but it's by far most expensive option and that's a direct replacement module sold by Saegenspezi: http://m.ebay.co.uk/itm/190590733267?_mwBanner=1 which I believe are based on a universal ignition module and coil on a purpose made plate.

So I tried two caps in parallel, no dice. I could still feel a low voltage pulse if I held the lead wire...

Then I added a Stihl 1118 trigger by scraping off some PVC insulation from the grey primary wire to the coil, and soldered the wire in tee tap style, still no dice. Just had one cap wired in. Could feel a dam hard pulse where I had to let go of the wire though...

Finally, I completely cut off the grey secondary wire between the tee tap and the old PC board, thus isolating the new cap/old epoxied PC board, and now I have a runner. Big blue spark!

Speculation only, but I'll bet the Darlington transistor or a diode in the old board PC was bad all along.

Next step is to grab the timing light and a 12 volt battery to check the recommended 26 degree advanced timing marks.

 

[tntatro]

I suspect in those cases where this fix fails it's not a case of the capacitor value only being close enough but much more likely that any one of the other vintage electrical components in the module that has failed in addition to / instead of the capacitor.

Luckily you get a second chance of success with a Nova II / universal ignition module and I've yet to read about anyone failing with both fixes.

There is also a third option but it's by far most expensive option and that's a direct replacement module sold by Saegenspezi: http://m.ebay.co.uk/itm/190590733267?_mwBanner=1 which I believe are based on a universal ignition module and coil on a purpose made plate.

I've actually recently had 4 fails in a row which has taken my 100% success rate for the fixes to around 50%. I always try the Foggysail fix first and if that doesn't work then I use a Nova module.

At first I had two successes with the Nova modules and thought that the coil parts rarely failed. The last four that I have tried were unsuccessful with both methods of repair. One was from a points ignition using a Nova module and it would only spark a little at first and then nothing. Another had a very weak spark and I didn't even bother putting the saw together to try it. The last two had decent spark and the saws would start and run for a while but after using them a while they would be hard to start. I found that if I cleaned up the spark plug or put a different one in then they would go a little longer until I had to start it again.

Today I tried the two successful Nova fixes I had and found that I was able to mill a small log into building materials between using the two saws but there was some hard starting. I'm beginning to think that if the Foggysail fix doesn't work then it's likely the coil will not last much longer although I could be wrong. The ones I thought were successful gave me no problems at first but after using them a bit they started showing signs of ignition failure.

I had three successful Foggysail fixes and they all worked flawlessly with no problems and I used them a lot.

Other options that I have discovered are the Sagenspezi ignitions. There is one for around $110 shipped and there is another for around $65 shipped. The $110 one is a direct fit with the Bosch electronic flywheel and worked great for me. The $65 one is for a points ignition but I discovered that it's possible to use a Bosch electronic flywheel on a points ignition. The poles are the same but the key way and timing mark are different. Basically, advance the timing a flywheel key width (same as with Nova module) and it should work, it did for me anyway. So I believe that of you find a good points ignition then you can use your Bosch flywheel (if you have the right crankshaft) and the $65 Sagenspezi should also work but I have not confirmed it yet. I haven't tested this thoroughly, just started it and made a couple small cuts with a points ignition and Bosch electronic flywheel advanced one key width.

If you already have a Nova module then you could get a new coil but they cost the same as the $65 ignition so it's better to get the ignition because it has a new spark plug wire and switch wire also. The coil on the Bosch electronic has a different part number than the points coil but I believe they are the same.

If anyone has suggestions for the failed Nova module fixes then I'd like to try but I think the coils are toast unless all my modules are junk.

 

[Chesnimnus]

Other options that I have discovered are the Sagenspezi ignitions. There is one for around $110 shipped and there is another for around $65 shipped. The $110 one is a direct fit with the Bosch electronic flywheel and worked great for me.

I just bought the one from Saegenspezi for the 056 Bosch unit. There were no instructions provided. The new unit appears to be clocked differently than the old Bosch unit. The screw holes are slotted to allow rotation for timing. So, how do I put this in and time it correctly? None of my old timing marks mean anything now.

 

[tntatro]

I just bought the one from Saegenspezi for the 056 Bosch unit. There were no instructions provided. The new unit appears to be clocked differently than the old Bosch unit. The screw holes are slotted to allow rotation for timing. So, how do I put this in and time it correctly? None of my old timing marks mean anything now.

It should be a direct fit. If you install it at one extreme or the other then it should still work. If you install it all the way clockwise then it will be advanced as much as possible. You will know if it is advanced too much if the recoil starter snaps back when you pull it, it should be fine though. I'm assuming you have a Bosch electronic flywheel with the aftermarket Bosch electronic replacement ignition.

 

[Chesnimnus]

Thanks. Yes, it was the Bosch electronic ignition. Other hidden tasks include buying two new 4mm screws because the base plate is thicker, and installing a female bullet connector on the wire to connect to the new module. Installing that new connector resulted in the old insulation cracking, so I had to remove the old wire, peel off the old broken insulation, install heat shrink tubing along the entire length of the wire, and reinstall.

 

[OTAlucard]

I Am going to try to mod one of those 070 Ignitions to fit under the flywheel of a 041 av lol when it cools off a bit It might work you never know
!!!

 

[Drago]

Buongiorno a tutti ho una dolmar 152 dell'epoca senza corrente, volevo cimentarmi ad apportare la modifica illustrata in questo post
Good morning I have a dolmar 152 of the time without current, I wanted to try to make the editing illustrated in this post







la domanda è posso usare questo condensatore?
The question is I can use this condenser?

http://www.sky-macau.com/Products/4...-400V-824-824J-082uF-820nF-5-P6135095635.html
http://www.electroson.com/producto/condensador-placo/P820K630C

Grazie
Thank you

 

[Greenmachine]

I'd like to express my deepest thanks to foggysail for the fix. Also The Chainsaw Guy for alerting me to this thread.

My 056 is my first chainsaw. After being weened off my father in law's 031 I was ecstatic to buy this used 056 for $150 CAD. It was always challenging to start, even after being serviced. It would shut down when hot, not stay tuned, and eventually it wouldn't start. It leaked oil through failed repairs too.

About four months later I've finally got an excellent saw thanks to the work of foggysail.

It fires right up now. What a joy after months of yanking and yanking.

I also replaced the starter spring, rebuilt the carb, fuel filter, and mostly fixed the oil leak. It was leaking from like five different places. Yeesh.

Thanks again!

 

[PogoInTheWoods]

Good to hear. It's a great feeling when you get an old saw straightened out and running right. Out of curiosity, where did you find a replacement capacitor and what value did you use? My next project is my 056. I'm switching to the Bosch setup from a failed SEM ignition. Have the flywheel and module, just need a cap.