deerhunter77
ArboristSite Lurker
I have one also. Let me know and it is yours..
SUCCESS!!! Just repaired Stihl 045/056 Bosch electronic ignition!!!!!
- Thread starter foggysail
- Start date
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046--
Please be patient. All of us have suffered from Bosch's unit. As soon as I get a couple of units, I will post pictures and instructions that I believe you NEED. Without them you just run the risk of screwing up a repairable ignition. One thing you can do in the mean time if not already is purchase those capacitors I recommended.....AND NO, I AM NOT THE GUY SELLING THEM : - )
deerhunter77
ArboristSite Lurker
I will ship mine out next week. No worries about the shipping.
Duke Thieroff
Fill your hands, you SOB!
I'll send one over too if your others happen to call through....
MechanicMatt
Cut Split Stack Burn
Foggy I talked to my buddy with the 056magII, he'll bring it in to work monday, where do we ship it to? And do we get it back working?? Could always use a spare? Or do you have enough on the way? Should we hold tight for now and wait for the "fix" to be posted???? When I told him about this thread of yours his eyes lit up, hehehehe. Got a old guy to think there was hope for his beloved ole saws. He has a collection of old magnesium stihls. 045's and a couple 056's
Rockfarmer
ArboristSite Guru
You got my attention!! Thanks!!
big t double
Addicted to ArboristSite
opcorn: Popcorning in to this one...have two 056's sitting in my basement in line to be tinkered with. 
Rockfarmer & BigT--
At least two ingnitons should arrive soon. So hang onto yours unless those expected don't arrive for some reasons.
I continue to suggest to those of you who have problems, purchase the needed capacitors from Ebay while available. Sure, capacitors are not in short supply but those on EBay are very inexpensive. I am going to put together the instructions as quickly as possible after the dead ignitions arrive so the "fix" can REALLY get tested out there in the field.
If the field test confirm my expectations, I believe we will see fewer low priced 045/056's out there on EBay.
Foggy
At least two ingnitons should arrive soon. So hang onto yours unless those expected don't arrive for some reasons.
I continue to suggest to those of you who have problems, purchase the needed capacitors from Ebay while available. Sure, capacitors are not in short supply but those on EBay are very inexpensive. I am going to put together the instructions as quickly as possible after the dead ignitions arrive so the "fix" can REALLY get tested out there in the field.
If the field test confirm my expectations, I believe we will see fewer low priced 045/056's out there on EBay.
Foggy
What's the voltage rating for the capacitors for this application?
Foggysail I will be following this thread with great interest. It looks like you are sorted for some more ignitions but I would have been prepared to send you one from the UK. There is a 056 Super with ignition problems on UK ebay that I will now be watching with some interest. AS has been lacking this sort of thread lately so well done for posting.
towingace
ArboristSite Guru
I'm excited as hell about this thread! Good goin' Foggy.
The voltage rating on the old caps is 400. But you do bring an interesting question to the forum. The correct voltage rating? Unfortunately I don't know because I cannot put my oscilloscope across the cap, hold the saw down, pull the starting cord and look at the charging waveform all at the same time. So I settled with the 400v, same as the original. Now all things are not equal here. The original cap is physically smaller along with being slightly less capacitance at 0.8 uf. So the value of convenience (1uf) is 20% greater than the 0.8 original value. Further, Bosch probably worried about the limited available volume which could have moved them to the 0.8uf selection. And then they potted everything and stuck it into a place where there is little cooling where high operating temperatures affect the device's life expectancy.
The higher value that I am recommending could result in slightly less spark voltage. Note the charge voltage on the capacitor is transformed (so called coil) to a high voltage related to the transformer turns ratio. OK but the capacitor's voltage is governed by he equation (I*T/C). The larger value of C will result in a lower charge voltage when used in the same application. I don't think that's a problem.
I will try if I can get local help to see what the charge on the cap actually is... at pull cord RPM. But consider the worst case where the voltage is higher than the capacitor's rating. Further assume it causes a future problem. Well, not a real problem like we have faced up until now because if one of our new caps have a voltage failure, heck, we can just upgrade to a higher voltage device. And again remember from the previous paragraph, because the suggested new capacitor's value is 20% greater, the peak charge will be 20% lower voltage.
A little technical although I believe most can understand my dialog. And Jacob-- good question : - )
Foggy
Thanks Maico--
LegDeLimber
Addicted to ArboristSite
It's been over 20 years since I dabbled in any of this stuff.
....was looking at inverters for powering some automotive audio amplification.
I would consider myself as one of those people with "a smattering of ignorance about many things"
on my BEST day.
The cap value makes me curious if it affects timing of some event.
Say a trigger threshold gets delayed till cap is charged.
could this allow the magnet to a bit far past the laminations when the trigger voltage is reached?
Will the value change affect the timing curve?
Yeah, yeah velocity of magnets past the iron, gap size and all that other stuff counts too.
Some of those funky tails and tapers or leg numbers, magnet count etc
of the various ignition iron
have had me wondering how they affected things.
Any idea what the failure mode of the original capacitor was?
Was it an electrolytic, if so did the heat dry it out?
thermal cycling stress.
vibration causeing chaffing/shorting in the layers
You mentioned things being potted, but could the leads still pulled from shaking
of the insides?
some sort of repeated assembly line oopsies?
Seen plenty of them in metal fabrication.
Not meaning to seem nit-picking ( I'm far too un-knowledgeable for that )
Just that your post/thread sort of woke up some little used portion of my brain and now
I'm just curious to see what Ya got going on!
You mentioned scoping things out. any chance there's a nasty spike or coil ringing pounding it?
I blew a small, polarized, cap in my ignorant putzing around with a self oscillating (center taped) coil
and transitors rig up.
Went off like a 22 short. stunk like heck and a little polyester streamer and odd bits scattered around the room.
Still got a pile of stuff crammed away here from those days.
....was looking at inverters for powering some automotive audio amplification.
I would consider myself as one of those people with "a smattering of ignorance about many things"
on my BEST day.
The cap value makes me curious if it affects timing of some event.
Say a trigger threshold gets delayed till cap is charged.
could this allow the magnet to a bit far past the laminations when the trigger voltage is reached?
Will the value change affect the timing curve?
Yeah, yeah velocity of magnets past the iron, gap size and all that other stuff counts too.
Some of those funky tails and tapers or leg numbers, magnet count etc
of the various ignition iron
have had me wondering how they affected things.
Any idea what the failure mode of the original capacitor was?
Was it an electrolytic, if so did the heat dry it out?
thermal cycling stress.
vibration causeing chaffing/shorting in the layers
You mentioned things being potted, but could the leads still pulled from shaking
of the insides?
some sort of repeated assembly line oopsies?
Seen plenty of them in metal fabrication.
Not meaning to seem nit-picking ( I'm far too un-knowledgeable for that )
Just that your post/thread sort of woke up some little used portion of my brain and now
I'm just curious to see what Ya got going on!
You mentioned scoping things out. any chance there's a nasty spike or coil ringing pounding it?
I blew a small, polarized, cap in my ignorant putzing around with a self oscillating (center taped) coil
and transitors rig up.
Went off like a 22 short. stunk like heck and a little polyester streamer and odd bits scattered around the room.
Still got a pile of stuff crammed away here from those days.
sachsmo
Addicted to ArboristSite
Can't wait for the details,
I have fixed several Bosch units, but have never got into the 'potted' stuff. (grounding issues)
However with the help of youtube I did fix our Samsung (TV) start-up problem by replacing the 10 volt caps with 25 volt caps in the power board.
So what is special about the caps in the Bosch unit? And how do you 'melt' the 'potting'?
Glad to have a circuit designer on board, where were you 8 years ago when I shelled out $100 for one (after searching for a year)
I have fixed several Bosch units, but have never got into the 'potted' stuff. (grounding issues)
However with the help of youtube I did fix our Samsung (TV) start-up problem by replacing the 10 volt caps with 25 volt caps in the power board.
So what is special about the caps in the Bosch unit? And how do you 'melt' the 'potting'?
Glad to have a circuit designer on board, where were you 8 years ago when I shelled out $100 for one (after searching for a year)
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.
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