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

[PogoInTheWoods]

The kill switch. Worth replacing with better (or new) wire as it is notoriously prone to insulation rub-through and shorting to ground.

Adding a third wire is entirely up to you, I used black so I would not mix it with the others. I cut the shutdown wire that goes to the on/off switch and replaced it with this third (black) wire.

 

[Joshjd49]

Working on performing this fix to my 056 super today. I removed the flywheel and I have a different ignition than what the pictures look like. Upon reviewing this thread, it appears to be a bosch ignition not an SEM. The part number on the ignition is 2-207-031-114. Can this type of ignition be fixed with this solution?

 

[mgr]

This fix from Foggysail is for the Bosch ignition type. The type from your picture is a Bosch so you can try to make it work again.

 

[PogoInTheWoods]

Correct. This is a SEM ignition.

 

[Joshjd49]

This fix from Foggysail is for the Bosch ignition type. The type from your picture is a Bosch so you can try to make it work again.

Correct. This is a SEM ignition.

Ok, that is good news. Question: What do I need to do with the 2 wires coming from what I believe is the coil into the potting? I feel like when I remove the potting the 2 wires will get destroyed.

 

[mgr]

Here do you need removing some epoxy poting.

 

[Chris_the_wrench]

I just joined this site after finding it with a google search for "stihl 056 ignition problem'. I've had this saw for about 12 years and it's worked great for me. In the past few years in started shutting down after 20 minutes, but then just before Christmas(after the nasty Eugene ice storm) it died and wouldn't restart. Luckily I found this thread. ANYWAYS, thanks! I ordered my capacitor from digi-key and had it a couple days later. Part #399-12847-ND. I was surprised by it's size(huge) when it arrived. I installed it according to the instructions but still had no spark. I installed a new spark plug wire so I figured I bunged that up and that was my issue, but that checked out ok. I went back to the beginning of everything and realized I didn't cut the circuit path on the board enough. I redid that, bench tested the unit and had spark! Reassembled the remainder of the saw and went and cut some wood. All good now! Tomorrow I have about 4 hours of cutting ahead of me, a real test.

Thanks again!
-Chris

 

[globtrotter69]

Done

 

[PogoInTheWoods]

You could weld with that spark!

 

[Joshjd49]

Here do you need removing some epoxy poting.

Ok, I'm a little confused. I don't know if I am missing something in the directions or something else. See the picture below for the noted differences in my ignition:



Any advice on how to handle the fix with the noted differences?

 

[PogoInTheWoods]

You will still most likely find the same circuit trace in the same general spot as the pic in post #587 above. You only need to remove the potting in that area which should not affect the wires unless you severely overheat the potting trying to soften it for scraping.

 

[foggysail]

Hi Guys--

Been awhile since I visited the forums and was surprised to see that my old thread still has activity. I noticed that many who implemented my fix believe they have timing problems. I want to assure all that the "fix" should not affect timing! The function of this capacitor in the circuit is to act as an energy storage device that is charged (energy is put into it) and discharged creating the spark. The charging event is fixed with the magnets on the flywheel. The discharge event is also determined by separate capacitor's charge ( call this a trigger charge) reaching a voltage of about 1-3 volts that fires an SCR (silicon controlled rectifier)

The easy way to explain the SCR is to consider a toggle switch and the "toggling" occurs with the 1-3 volts I described above. The capacitor for this function is low voltage and the charging and discharging of it is kind of unique because at higher RPM the capacitor with the aid of some other components (don't want this to get complicated) triggers the SCR earlier than at low RPM. Clever! The saw has a built in self advance at high RPM.

It is important to be careful of the wire that exits from the potting to the shut down switch. That POS wire used German insulation pushed by environmentalists that self destructs at high temperatures. I found that the combination of the POS switch and the POS wire got to me! I finally cut that wire at the potting and chucked the switch. The saw shuts down almost as fast using the choke. If any part of that insulation fails allowing the bare wire to touch any metal, the ignition is shut down just as if the switch was turned off.

Good luck all--

Foggy

Hi, thanks for info.. I have a question, you said you added 3 wires, 2 yellow and 1 black, where did you conected the black wire?
Thanks!

The black wire goes to the POS switch. The original wire has an insulation problem

 

[62alf]

Foggy, glad to see your still around! I'm sure many are as grateful for your efforts as I am. Thank you again.

Sent from my GT-I9295 using Tapatalk

 

[foggysail]

Foggy, glad to see your still around! I'm sure many are as grateful for your efforts as I am. Thank you again.

Sent from my GT-I9295 using Tapatalk

You're welcome

 

[tubastuff]

.....For those inquiring minds about the inside of the Bosch Ignition........see pic..........Also the blue thing is the cap that goes bad.....VERY cheaply made...actual value is .8uf/400voltsView attachment 546687

It appears that the capacitor is the only thing contained in the potting compound of the far "leg" of the assembly. I'm getting ready to dig into my 056's ignition and am wondering if tying into the circuit on that far leg instead of modifying the PCB might be a better approach. Has anyone tried this?

For what it's worth, if you can't find the 0.82-1.0 uF 400V capacitor, a pair of 0.47 uF 400V capacitors in parallel will do the job and might be easier to find.

 

[tntatro]

It appears that the capacitor is the only thing contained in the potting compound of the far "leg" of the assembly. I'm getting ready to dig into my 056's ignition and am wondering if tying into the circuit on that far leg instead of modifying the PCB might be a better approach. Has anyone tried this?

For what it's worth, if you can't find the 0.82-1.0 uF 400V capacitor, a pair of 0.47 uF 400V capacitors in parallel will do the job and might be easier to find.

I think that is what the repair is. Breaking the circuit to the old built in capacitor and making a new circuit with a new capacitor in it. I don't know what the PCB is, I just do it the way that is instructed and it has worked for me. Do you mean just cut that wire and run a circuit with a capacitor directly from the wire on that side?

I've done five or six now and only one did not work so I repaired it using a Nova II module instead. Out of the others that worked, one has failed because I accidentally overheated the saw and also destroyed the piston and cylinder. I also repaired that one with a Nova II. So far I have a 100% success rate for Bosch electronic ignition repairs for this Model. I like this fix better because you don't have to change the timing.

 

[PogoInTheWoods]

.... am wondering if tying into the circuit on that far leg instead of modifying the PCB might be a better approach.

That's what you do. Cut the trace to the failed cap (under the potting) and tie in the new cap mounted externally. Two of em in parallel may be a bit cumbersome to effectively mount in the suggested location, tho. Now if you mean remove all of the potting and the old cap to use that area for a new cap, not sure there would be enough space even for the desired replacement cap, let alone a pair to obtain the appropriate value. Then there would still be the heat issue...

 

[tubastuff]

That's what you do. Cut the trace to the failed cap (under the potting) and tie in the new cap mounted externally. Two of em in parallel may be a bit cumbersome to effectively mount in the suggested location, tho. Now if you mean remove all of the potting and the old cap to use that area for a new cap, not sure there would be enough space even for the desired replacement cap, let alone a pair to obtain the appropriate value. Then there would still be the heat issue...

All I'm suggesting is that rather than risk making a hash of cutting traces on the circuit board, it might be safer for us cowards to sever the cap lead on the far end, nearest the capacitor. I'm thinking that if I foul up on that, I still have the circuit board mod option.

 

[PogoInTheWoods]

Let us know how it goes.

 

[hotshot]

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.