Test SCR
 

Perfect, I tested my SCR and the result is positive.
First I switched S2 and after I pushed S1, and the lamp stays on ( 3 watt + 3 watt)

WP 20141110 21 27 01 Pro - YouTube

Now, who is the guilty? :confused:

Does anyone know what to do?

Hello all

Thanks for this very useful topic!!!

Can someone help me out with an OT104 thyristor? We found out that's the part that got broken in the CDI but can't find a new one and don't know if it could be replaced by some other part that have similar function?

Any help would be very appreciated!!!

Thanks!

Wout
almost desperate to get my '74 chocolate brown rolling :rolleyes:

The best replacement for this thyristor i have found in Europe is the BTW30-800 from STMicroelectronics. It has the same package (TO-48) and is specified with a Tq max of 12 µs.

The replacement by a International Rectifier 50RIA80 or similar which is not specified with a Tq max is at risk of blocking when operating at high temperature.

Thanks!!!!

gr
Wout

Excellent information. Thanks!

Very good thread!, subsd.

There are should be US version of the BTW30-800 replacement...

The electrically equivalent thyristors I found with a 2Nxxxx number are not using a TO48 case.
The 2N692A Which in available worldwide is not specified with a Toff max.
It is specified with a Toff typical (not max) of 15 µs by only one US manufacturer : Central Semiconductors Corp, Hauppauge NY.

Hi jmchrist

Have you received my pm?

Thanks for the information!!!

gr
Wout

Transformer
 

Thanks for these useful info!
Does anybody know what transformer is used in this circuit (windings,...) and/or where I can get that part?

Thanks

Thanks for these useful info!
Does anybody know what transformer is used in this circuit (windings,...) and/or where I can get that part?

Thanks

does anyone have more info about this bosch unit?

http://forums.pelicanparts.com/uploa...1454426909.jpg
http://forums.pelicanparts.com/uploa...1454426926.jpg

This may help:
TSZ Zündung CIH Manta 400 BMW 1802 GTI 914 Capri 1 W109 Golf 1 in Aachen - Aachen-Brand | eBay Kleinanzeigen

I could be wrong but this is essentially very similar to the ignition transistor output stage found in an early Bosch DME.

The box gets triggered by the distributor and replaces the classic points. It charges the primary of the coil. Think of it as transistorized Kettering setup.

Ingo

Can a similar test be performed on the 6 pin CDI?

You can duplicate the test and use a square wave generator for the distributor I have done it on the bench many times.

Can I manually turn the distributor, since it is off the car?

I have a rebuilt SC motor, with unknown history, which will go in to my '71. I hope to verify the SC's CDI operation before I build a custom harness.

Thanks.

You can trigger the 6-pin by hand with the distributor or even with an AA battery but ideally you run the box over night at high RPM to ensure it'll not shut down when it gets hot. When I test boxes some fail only after 6h - 8h and you'd never catch that with a quick test. Alternatively you'd have to put the box into an oven heated to ~150 degF to simulate engine bay conditions.

That's why some sort of automated trigger (e.g. signal generator or your drill connected to the distributor) is preferred.

See here for a simple triggering device for 3-pin and 6-pin boxes http://forums.pelicanparts.com/porsche-911-technical-forum/375120-6-pin-cdi-problem-under-temp-6.html#post3615049

Good info.

One more quick question. On the three pin CDIs the coil has a pigtail ground to the fan housing. This is not used with the 6 pin box. Would there be any advantage for using a ground to the fan housing with the 6 pin box?

Thanks,

I doubt it. The coil needs to get GND the same as in a 3-pin since the schemtic and topology is identical to the 3-pin. However, in the SC it's through the harness and that should be sufficient.

Cheers,
Ingo

Question for those reading this Forum - I am in the process of repairing my Bosch 6-pin CDI (1982 Porsche 911 SC Targa) and have noted the changes suggested to date in this Forum due to obsolete / no longer manufactured components.
It appears to me that total rebuild to the original Bosch design (albeit slightly modified) would be more time/cost effective. (.
I was wondering if anyone has manufactured the original Bosch CDI printed circuit board on fiberglass (FR-4 glass epoxy). If so, how do I acquire several on these boards?

Quite a few thyristors are mentioned as replacements for the original OT-104 with a TO-48 housing for the 3-pin CDI.

In post #84 the BTW30-800 is mentioned.

And in this other thread, InternationalRectifier 16RIA80 or 25RIA80, Siemens CS23-8, or the -10, -12, or -16 versions are pointed out:
http://forums.pelicanparts.com/porsche-911-technical-forum/173895-bosch-cdi-discrete-components-troubleshooting.html

Some say these components will work, others say the won´t.

I am not sure if any of them will work.

My Bosch repair shop tells me a new thyristor is all they need to make my original 3-pin CDI box work again. But they can´t get a replacement part anywhere.

So which one should I go for?

Bosch Classic seems to be unable to help.

Any help would be appreciated.

Contact Bob Ashlock at AshlockTech. He rebuilt my 1970 CDI 3-pin and upgraded it to modern internals. Very quick turn around, and now a reliable unit.

https://ashlocktech.com/bosch-cdi

Please fully describe what "modern internals" actually means.

Do a Google search, as there are numerous sources for Bosch CDI repairs starting at $225 with a 5 year warranty.

In my experience most SCR first appear to work but then quickly show issues when the box is at operating temperatures. The comutation fails and the SCR doesn’t turn off properly.

Sourcing an appropriate type isn’t trivial to say the least.

Here is the info,

https://ashlocktech.com/ashlocktech-cdi

That CDI is NOT a typical original Bosch reuild! It's another design with questionable reliability;

From the link -

"The SINGLE-PLUG unit is a direct form/fit/function replacement for your old 3 or 6-pin Bosch unit. Modern, reliable electronics
is installed in your old Bosch donor housing to maintain a desirable 'stock' appearance. An added convenience is that a
3-pin unit can be converted to 6-pin or vice-versa if desired."

"AshlockTECH High Performance CDI UNIT $500
Customer sends their own core unit to be cosmetically restored and retrofitted with all new modern high performance electronics.
(Add $150 for outright purchase - no core)"

When that modified CDI fails, it becomes a bad non-repairable core, i.e. junk like this one;

http://forums.pelicanparts.com/uploa...1664905748.jpg

Beware of what you buy and put in your 911!

Chime

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

Actually it’s the older design Bosch that is less efficient with dated components that also waste more of the incoming energy as heat. Old Bosch CDI units are also prone to sudden failure and one of the culprits that will leave a driver stranded.

In addition, there are at least two other modernized CDI designs trying to address the same original design flaws of the original Bosch unit - P:::sK:::::k and Classic Retrofit.

Bob Ashlock is a top shelf gentleman that puts out a great product at a very fair price. So far he has done two CDI boxes for me (and does work for our host - search CDI rebuild) and they both work flawlessly.

https://www.pelicanparts.com/More_Info/ATCDIREPAIR.htm?pn=AT-CDIREPAIR


Bob is one of the good guys.

Laughable! Where are your data, please? How many millijoules of energy is wasted?
You do know how to measure potential spark energy and losses, right?
Please define which components are dated. You do know the difference between an active & passive electronic component?

Really? Let's not continue to provide hyperbole! Provide some data. Post a picture of the inside of your "modern" CDI,
with some oscilloscope images of the spark output.

It's unfortunate that you weren't able, e.g. lack of knowledge, to directly respond to the above issues.

The link you provided basically is just an analysis of the how the Bosch CDIs function and doesn't directly relate to the specificity of the "modern" CDI.

https://forums.pelicanparts.com/porsche-911-technical-forum/938050-bosch-cdi-voltage-regulation.html

There's a Bosch CDI rebuilder, a previous Pelican supplier, that's been rebuilding Bosch CDI's and other Porsche electronics for over 40 years
with a five warranty to Porsche independents and dealers, and a zero failure rate.

Hi Dave/Loren - I see I've stumbled upon your pseudonym account and you have a business rebuilding stock electronics. You've already discussed this at length with folks like Jonny and Winterburn that know much more than I.

https://forums.pelicanparts.com/porsche-911-technical-forum/938050-bosch-cdi-voltage-regulation.html


Hmmm - I wonder who this rebuilder could possibly be - "Dave"?

Popcorn time:
Act one: Loren on the merits of chip Tuning
Act two: Correlation of basic intelligence and ability to troubleshoot a 3.2 no-start
Act 3: Bosch CDI vs. aftermarket solutions
Epiloge: don’t take your business anywhere - they’re all scammers !!!

Appendix A: Inductive is better than CDI except for Standard Bosch CDI which is better than sex.

Pelican Parts direct competition, i.e. rebuilt CDIs, Motronic DME ECMs, & performance chips, allowed to advertize?
What prevents other competitors from doing the same?

http://forums.pelicanparts.com/uploa...1665094689.jpg

Nothing stopping you but I guess it’s difficult to advertise your skills if you’re pretending to be someone else! Must be annoying.

There wasn't any implication of that. But for those really interested in changing to an overall better ignition spark, i.e. inductive discharge, then consider this;

http://forums.pelicanparts.com/uploa...1665175701.jpg

It's a very simple setup with ignition map programming using an inexpensive coil, e.g. Bosch blue coil.
The IDI mode, used on all present day internal combustion engines, provides longer spark burn times than CDI systems,
e.g. more complete combustion. Furthermore, IDI systems are inherently more reliable than a CDI system, no need for a capacitor.