6-pin SC/Turbo CDI unit repair documentation
 

Well, after a bit of a delay ...

Here's the schematic and replacement parts list for the Bosch 0.227.300.004 6-pin CDI unit, cussed & discussed at great length ... and used on SCs & Turbos thru '89!

http://forums.pelicanparts.com/uploa...1138414059.jpg

http://forums.pelicanparts.com/uploa...1138414270.jpg

http://forums.pelicanparts.com/uploa...1171863884.jpg

http://forums.pelicanparts.com/uploa...1183619700.jpg

http://forums.pelicanparts.com/uploa...1138415968.jpg

http://forums.pelicanparts.com/uploa...1090013680.jpg

http://forums.pelicanparts.com/uploa...1090013691.jpg

http://forums.pelicanparts.com/uploa...1090013700.jpg

Great work Warren. This is what makes this board as great as it is.

Tim

Excellent, Warren!

Awesome!
-Chris

Now somebody post a circuit board pic

- That's defintiely $400 worth of parts isn't it.....

Warren,

Thanks!

Here is the thread on the Bosch 3-pin. It has a wiring diagram also.
http://forums.pelicanparts.com/porsche-911-technical-forum/160537-perma-tune-cd-bosch-cd.html

Best,
Grady

Very cool. I just wish I understood.

Which of those parts fails, typically, when a Bosch CDI unit stops working?

Very Nice Warren!

Superman, I think the Thy might have the best chance of going bad. of course, there is always the chance of a blow cap, diode or resistor.

Too true, Supe...we mere mortals wouldn't understand. But in the right hands, this info is valuable. I try to have the info on hand for those with the right hands. ;)

Component replacement and checking is not that hard on these older analog items. You could take a course at a community college and I'd bet 1 course would do it. This also helps stave off Alzheimer's if you are turning gray... If you screw it up, then send it in for re-grooving by a pro.

Great work Warren...

Another question - what about the pin-out for the 6 pin connector? Is there any place I can find that?

thanks...

Here is the pinout looking into the connector with the mounting flange sitting on the hand or table ...

. 31/1 ... TD ... 31d

. A . . . . 15 . . . 7

==============

31/1 -- Power ground
31d -- Signal ground [green coax shield] for trigger signal

15 -- +14 Volt power lead

7 -- Trigger signal from distributor magnetic pickup coil

TD -- Tachometer Drive signal

A -- +460 Volt pulse output to coil

Here are some resources worth reading if you are a bit rusty on the theory of operation ...

http://www.irf.com/product-info/thyristor/manual/scr_manual.pdf

http://www.st.com/stonline/books/pdf/docs/4347.pdf

http://www.st.com/stonline/books/pdf/docs/5201.pdf

And, here is an application note from RCA that may be helpful ... after much difficulty with pic uploads [never copied the image code to edit window -- multiple attempts] ...

http://forums.pelicanparts.com/uploa...1107621185.jpg

http://forums.pelicanparts.com/uploa...1107621275.jpg

http://forums.pelicanparts.com/uploa...1107621352.jpg

http://forums.pelicanparts.com/uploa...1107621506.jpg

http://forums.pelicanparts.com/uploa...1107621640.jpg

http://forums.pelicanparts.com/uploa...1107621710.jpg

http://forums.pelicanparts.com/uploa...1107621796.jpg

http://forums.pelicanparts.com/uploa...1107621984.jpg

http://forums.pelicanparts.com/uploa...1107622083.jpg

http://forums.pelicanparts.com/uploa...1107622191.jpg

And, here are the last two pages of AN-6288 ...

http://forums.pelicanparts.com/uploa...1107624336.jpg

http://forums.pelicanparts.com/uploa...1107624504.jpg

I nominate this entire thread to become a PP Tech Article. Invaluable information from Warren as always, Thanks!!!

Here is a bit of design info from GE Semiconductors Electronic Data Library #400.6 on the single-transistor inverter as used by Bosch in our CDI units:

http://forums.pelicanparts.com/uploa...1108977264.jpg
http://forums.pelicanparts.com/uploa...1108977350.jpg

Truly awesome. Adding to the knowledge bank, Warren!

Randy,

Thyristor is an early name for a Silicon Controlled Rectifier (SCR). The name is a combination of Tryratron tube and transistor. The beauty of an SCR is that a miniscule current or pulse can turn on a huge current and it stays on until the source current drops below a certain threshold. This is used in CDI and household dimmers.

Best,
Grady

You're right -- I was thinking of thermistor.... Dunno whether to blame it on age or elapsed time since I've done any electronics work... I'll kill that post.