3 pin CDI repair question

[HKZ Bob]

Dear folks, I have some specific question which is based more on the repair of an cdi.






When the CDI was assembles I measured with my AC Meter 38V on measure point 2.
I had a disconnect ( burned line) between ZD3 & R1. Somehow I had a high current before it go out of function.
I checked the 2N3055. Ok
The 82V Zenner Diode. Don't know how to test.
An now the part which makes me a little unsure in the Thyristor.
I have between Anode & Kathode only 48R (build out).
That value is strange. I thought it should be high resistance without load.
Who can help here.

Thank you team.

Bob

[HarryD]

Bob,

I know nothing about CDI repair but Warren Hall does. Try reading this thread and if you still have a question, post it as part of that thread.

History of Bosch CDI ... toubleshooting info, parts list changes, and schematics ...

[Lorenfb]

As always, when the DIY effort fails, call Pelican Parts,
e.g. Scott, John, Jason, or Wayne if necessary, & save future headaches.

Remember, Pelican Parts has many sources for parts which may
not show on their website.

Bottom line: Sometimes it's not worth it in the long run to be a DIYer for everything.

[Early_S_Man]

Bob,

Is the ZD3 Zener diode shorted or open as tested by a multimeter? If it is still shorted that would explain a burnt trace.

Is the SCR shorted from anode to cathode both directions as tested with a multimeter? That can happen after attempting to jump start a 911 with CDI.

If you don't mind rewiring a TO-220AB device ... 2N6405 or 2N6509 SCRs by OnSemi will work just fine at a bargain price from Mouser or Digikey. Tab must be insulated from heatsink, though.

[HKZ Bob]

Warren the 82V Zenner was checked and ok.
I replaced the Thyristor and the problem was solved.

I had a 200V Sinus at measure point 2 due to the fact the Thyristor was short.

Do you have the links from Mauser & Digikey.
Thank for your help.


If you don't mind rewiring a TO-220AB device ... 2N6405 or 2N6509 SCRs by OnSemi will work just fine at a bargain price from Mouser or Digikey. Tab must be insulated from heatsink, though.

bob

[Lorenfb]

"I had a 200V Sinus at measure point 2 due to the fact the Thyristor was short."

Do what? Totally impossible! A mis-diagnosis of the problem and a mis-understanding
of the functional operation.

Why a DIY effort when a failure of this unit can result in a stranded situation,
unless you're going to just keep the car in the driveway and revv the engine?
Furthermore, if you have no real knowledge of what you're doing or are getting
mis-information, a DIY effort can just result in damaged parts.

Again, let Pelican Parts be a source for this part.

[304065]

Originally Posted by Lorenfb

"I had a 200V Sinus at measure point 2 due to the fact the Thyristor was short."

Do what? Totally impossible! A mis-diagnosis of the problem and a mis-understanding
of the functional operation.

Why a DIY effort when a failure of this unit can result in a stranded situation,
unless you're going to just keep the car in the driveway and revv the engine?
Furthermore, if you have no real knowledge of what you're doing or are getting
mis-information, a DIY effort can just result in damaged parts.

Again, let Pelican Parts be a source for this part.

Why don't you help the gentleman out and while you are at it why don't you call Wayne and help him with his 959 CCM!

[Paulporsche]

For those of us who don't know about these things, what is the part in the photo, where is it on the diagram, and what does it do? Thanks.

[Early_S_Man]

Bob,

Here are the links:

http://www.mouser.com/

http://www.digikey.com/

Paul,

That assembly has the three major power consuming semiconductors mounted to it on an early version of the CDIs ... later versions have the power Zener bolted directly to the case.

[Lorenfb]

"Why don't you help the gentleman out"

1. Some shouldn't be rebuilding 911 engines (me).
2. Some shouldn't be rebuilding 911 transmissions (me).
3. Some shouldn't be rebuilding CIS fuel distributors (me).
4. Some shouldn't be rebuilding Bosch radios (me).
5. Some can do their own oil changes & brake jobs (me).

So, for items 1-4 most (me) should use Pelican Parts or other sources
for labor intensive efforts. Thus, some know their limitations while others
attempt efforts beyond their capablities even when helped by
knowledgeable others, which may in the long run do a disservice
to the DIY, e.g. a future failure because of the DIY's basic inabilities.

[C4 Pazzo]

Lorenfb,
1. Some have the interest and capacity to learn from others who have the knowledge and willingness to share.
2. Some like the challenge of learning how to fix something, rather than throw it away.
3. Some don't mind spending their time on an interesting project, rather than spending money (even if they have more of the latter than the former).

So, while the practical solution may be to have a professional solve the problem, or to buy a new replacement part, many of us prefer to go the DIY route for the enjoyment, among other reasons.

[ChrisBennet]

Some of you may not be aware, but Loren does the electronics rebuilds for Pelican.
-Chris

[shbop]

Originally Posted by Lorenfb

"Why don't you help the gentleman out"

1. Some shouldn't be rebuilding 911 engines (me).
2. Some shouldn't be rebuilding 911 transmissions (me).
3. Some shouldn't be rebuilding CIS fuel distributors (me).
4. Some shouldn't be rebuilding Bosch radios (me).
5. Some can do their own oil changes & brake jobs (me).

So, for items 1-4 most (me) should use Pelican Parts or other sources
for labor intensive efforts. Thus, some know their limitations while others
attempt efforts beyond their capablities even when helped by
knowledgeable others, which may in the long run do a disservice
to the DIY, e.g. a future failure because of the DIY's basic inabilities.

You know Loren, you're just a crabby little guy. Can't imagine your business is in skyrocket mode. I would personally avoid doing business with you at all costs.

[Lorenfb]

"Some of you may not be aware, but Loren does the electronics rebuilds for Pelican."

Actually no, Pelican Parts has MANY good sources for Porsche parts, or has the capabilities to find them. As a result, this has contributed to their success.

[ChrisBennet]

Originally Posted by Lorenfb

"Some of you may not be aware, but Loren does the electronics rebuilds for Pelican."

Actually no, Pelican Parts has MANY good sources for Porsche parts, or has the capabilities to find them. As a result, this has contributed to their success.

I stand corrected. Are you saying that Pelican does not send you CDI boxes to rebuild?
-Chris

[HKZ Bob]

Dear all,

thanks to all who supported my questions!
The Box is working fine now. It spend about two hours in fixing and I know a little more about CDI Boxes Boxes now.
The Thyristor was kind of short to ground. ( Anode / Kathode resistance 48R.) I did not figuered out if the failure path to point 2 was over the (R2)10R & (R3) 52 R & W1. That could be the reason whay I saw 200V Sinus on my scope. Never mind.

Thanks you Warren. He is the CDI King on the board.

Lorenfb do my a favor, go to Hawthorne & Imperial and get a girlfriend. Your comments are were a big self goal.

Thanks again to all.

Bob

[Early_S_Man]

That is great news, Bob! Glad to be of help.

[HKZ Bob]

Warren can I use the 2N6509 TG as a replacement.
TG for Lead Free.

bob

[Wayne 962]

Originally Posted by ChrisBennet

I stand corrected. Are you saying that Pelican does not send you CDI boxes to rebuild?
-Chris

No, we no longer have Loren rebuilding our CD boxes. Not our choice - it was his. About 3-4 years ago, Loren must have been having a particularly bad day, and said something so outrageous on the forums, that I gave him a 3-day suspension. I don't remember what it was, but it was pretty over the top, even for Loren. A bunch of people were complaining too, so perhaps my fuse was short back then too. Well, he hasn't spoken to me or returned my emails or phone calls since. I wish he would, as I truly believe that Loren is an asset to the community as a whole. He used to come in all the time and talk with Tom Gould when he dropped off the CD boxes. I think I only talked with him in person once, but he is a totally different guy in person than online. I think part of his online persona stems from a frustration with people on the forums who seem to talk about things they don't really know too much about. That can be frustrating for me sometimes too.

-Wayne

[HKZ Bob]

Warren could this Thyristor from Ruttosha T048 housing could be replacement for AEG Thyristor.

Bob

http://www.mouser.com/search/ProductDetail.aspx?R=16RIA100_1%2f4%22_UNFvirtualk ey64010000virtualkey640-16RIA100