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

Well, guys and gals ... while working on a 1972 production model CDI unit for a Pelican friend ... it seems that a bit of time needs to be taken to document some of the engineering change history of these CDIs. [edit] Confirmed by email that 'A' is beginning, and 'E' is the end of the windings!

This thread is intended primarily for documentation purposes, not dialogue, maybe a prelude to a Pelican Tech Article ... this thread will be the 74th that will show up in seaches for 'CDI' in the title ... previously I posted one for the later 6-pin Bosch CDI used in SCs and Turbos, so this thread will deal strictly with the 3-pin versions over the years 1969 thru 1977.

Someone out there who knows technical German [as opposed to conversational dielects] ... can help me and others with a small detail regarding the transformer ... there are three windings W1 - primary, W2 - secondary, and W3 - feedback ... the parts layout diagram labels the ends of each winding 'A' or 'E' such as W1A or W3E ... so what are the German words, and which is beginning, and which is ending of the windings??? I have added these labels to the schematics and parts diagrams/pics, since they are important details to be observed during disassembly and repair.

Bosch testing and service parts documents which I previously posted in the following thread were not dated, but are from slightly different times, as the schematic and parts layouts for the circuit boards and schematic are somewhat different. The test document seems to be from late 1973 [though not completely consistent with my early 1973 version schematic and parts list] and the parts document slightly later, as one 470 Ohm resistor, R4 -- present in 1973 and earlier versions was eliminated from the parts list and later parts layout and schematic. There are some slight discrepancies and mislabeling that show up inside/between the two Bosch documents, but they aren't significant enough to be called mistakes ... just typical typos in references that happen when multiple versions and revisions of documents exist during writing of technical documents.

http://forums.pelicanparts.com/showthread.php?s=&threadid=160537&highlight=bosch+ permatune

I will post pics and diagrams as they become available and edit/remove any that become redundant as revisions are made and typos/mistakes are discovered.

Any one with pics or other data can email me through Pelican ... if you want to add data to the compendium!

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

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

Here are the first of the Bosch documents:

http://forums.pelicanparts.com/uploa...1084538148.jpg

http://forums.pelicanparts.com/uploa...1084538217.jpg

http://forums.pelicanparts.com/uploa...1084538299.jpg

http://forums.pelicanparts.com/uploa...1084538375.jpg

http://forums.pelicanparts.com/uploa...1084538464.jpg

http://forums.pelicanparts.com/uploa...1084538571.jpg

http://forums.pelicanparts.com/uploa...1084538634.jpg

http://forums.pelicanparts.com/uploa...1082044649.jpg

http://forums.pelicanparts.com/uploa...1084551922.jpg

http://forums.pelicanparts.com/uploa...1084552092.jpg

http://forums.pelicanparts.com/uploa...1084552237.jpg

http://forums.pelicanparts.com/uploa...1084552517.jpg

http://forums.pelicanparts.com/uploa...1084552636.jpg

http://forums.pelicanparts.com/uploa...1084552788.jpg

This is the board layout/picture for the 1972 CDI unit ... it corresponds to the fig. 17 layout in the test document:

http://forums.pelicanparts.com/uploa...1118874175.jpg

Here is the early schematic for 1969 - 1972 CDI units ... Please note that the test point labels in the test document do NOT correctly correspond to all of the labels in this version of the schematic [TP #1 and TP#2 are OK for scope tests, but to short main capacitor -- TP#4 & TP#4a are used ] ... based on an estimated 1974/75 revision:

http://forums.pelicanparts.com/uploa...1138498607.jpg

Here is an annotated picture/layout for an early 1972 CDI unit corresponding to fig. 16 in the test document.

http://forums.pelicanparts.com/uploa...1138088834.jpg

Here is the revised parts list showing R4 and 33 Ohm 5 Watt version of R3:

http://forums.pelicanparts.com/uploa...1118874874.jpg

I have come across at least two major revisions (PCB board layouts) of the 3-pin boxes. Also sometimes ZD3 is one 12Volt and one 10 Volt diode in series covered in isolating tubing. Your image seems to be the earlier version, later version had components aligned only in either 0 degree orientation or 90 degree orientation as shown below.

http://forums.pelicanparts.com/uploa...1118895786.jpg

Cheers,
Ingo

the oracle has spoken

A number of errors exist in the schematics!

Ingo,

There are at least eight different board revisions up to 1973/74, and some more revisions for '75 thru '77! Probably 16 or more versions, total, as the one Bosch schematic I have is labeled 'Bild 15' ... and it isn't the last version for the '77 model cars!

Your pic is identical to my '227' date-coded unit built early in 1973 model production, and the last/best layout documented in the Bosch test document!

Here is the 1973 version schematic:

http://forums.pelicanparts.com/uploa...1138499120.jpg

This is the same board layout in my '73 unit date-coded 227 ... 27th week of 1972, which has both R4 and a 120 Ohm R3 pullup resistor . Note it has two D4 diodes, yet also still has R4.

http://forums.pelicanparts.com/uploa...1084551219.jpg

Another variation in component values for the '72 model is C11 ... 1.5 mFd instead of 1.0 mFd!

http://forums.pelicanparts.com/uploa...1119085181.jpg

Here is info on the last 3-pin CDI ... 0.227.200.008 from 1976 - 77:

http://forums.pelicanparts.com/uploa...1137805244.jpg

http://forums.pelicanparts.com/uploa...1137805438.jpg

http://forums.pelicanparts.com/uploa...1137869493.jpg

http://forums.pelicanparts.com/uploa...1137870868.jpg

Thanks Warren. Can you comment on your suggestions of replacement SCR types and how you came up with them? I tried to PM you but never received a response.

Cheers,
Ingo

Ingo,

I have had over 40 years of successful experience with International Rectifier SCRs, so it was no surprise finding an appropriate datasheet for an SCR to replace the CDI part. Trial installation of the IR parts I already had on hand, 16RIA80, worked well with no failures. Later, some 25RIA80s were tried, and they worked well, too. Recent pricing and availability checks at Newark found the qty 1 price for 50RIA80 @ $14.30, compared to $17.75 for the 25RIA80, so that seems like a good value for what should be a bulletproof solution for the CDI.

A few years ago I found some old stock Siemens CS23-10 and -12 SCRs from the '90s, and both worked quite well in the CDI units ... but those were a one-time deal, and I haven't found any equivalent Infineon parts available at all! A recent search found IXYS parts by the same number, and readily available from Digikey, so they seem like viable alternatives to the IR parts.

Finding the cheapest SCR around that will fit is not what I advocate ... considering the hassle of unsoldering the 17 wires on the board of the 3-pin CDI units.

One line of replacement parts I do not recomment is NTE ... they aren't cheap, but they also aren't JEDEC-registered, either, so I say leave them to the CB radio and audio repair techs!

ZD3 trouble
 

Hi Guys,
I have been fixing quite a few of these CDi boxes here in the UK for a various early cars and with no trouble. Now I have a unit that seems to keep blowing the ZD3 ! I have used a 1N5358B to replace the now obsolete ZM22. Now as far as I can see the 1N5358B is higher rated device, and as such should be capable of taking Over volt spikes far better than the original. But this is the 2nd device I fitted that has failed in this unit ! Can anyone give me any clues ? This is a protective device, designed to take out high voltage spikes and to prevent excessive Vce voltages taking down the transistors right ? Shouldn't it be protected by a series R, like R12 in the later units ? I haven't seen this R12 in any unit yet , do you know the value/power used ? What device are you guys using for ZD3 ?
Thanks in advance, this thread has been invaluable to me in fixing the units that I have fixed. Thank you for this mine of information
Tim Bennett

further to the above problem, I have two other units with dead thyristrors. I took the bullet proof approach, 50RIA100 devices. In both cases, one a 6 pin, the other a 3 pin, both units will drop into an self triggered mode (Permanently conducting) there, one can be triggered by straight into this mode at cold, the other more susceptible at high temps..... Any thoughts ?
I haven't been able to find a data sheet on the old AEG thyristor yet... this may help. Thinking some kind of Dv/Dt problem but the rise rates seem way too slow ! Argh... I'm more used to '1's and '0's
Cheers
Tim

You need to select a device with low tQ time. Ideally, it needs be be on the order of less than 30 usec. Typical tQ times for all the current off-the-shelf devices are on the order of 90 - 120 usec. This causes your issues.

Ingo

Hmm, I see. Having scoped the relevant points in the circuit, and searched on the net for suitable thyristors, I see the problem. Do you think I should experiment with the snubber circuit to see if I can extend the -ve voltage swing. What devices are being fitted as replacements ? Are you finding old stock devices ?
Thanks for your input
Tim

I once found a perfect fit albeit in an isolated TO220 housing. It worked like a charm. Unfortunagely, I don't remember the JEDEC number on top of my head. Other than that it seems to become more and more difficult to find fast enough devices. I don't know why but it has to do with the semicinductor process......

I am just adding this link to some more test info:

http://forums.pelicanparts.com/porsche-911-technical-forum/307317-cranky-cranky-no-sparky.html

Bosch CDI unit 0.227.200.008
 

I am new in this forum where I found very valuable information on CDI schematics that allowed me to repair a few units in France (I am a retired electronics engineer).
I am grateful in particular to Early_S_Man for his set of various versions of Bosch CDIs.
So I am willing to bring my two-pence contribution :
The schematics given above on CDI version 0.227.200.008 is incorrect.
When I measure the value of R12 resistor I found 15 ohms.
Since the consumption of a unit is between 1 A and 2.6 A, it is obvious that this resistor is not at the indicated place.
I have made the corrections I found on the attached picture, highlighted in yellow.
Please notice the added diode (D8) that seems to exist only on this particular model.
I hope this will be of some help.
http://forums.pelicanparts.com/uploa...1170978761.jpg

Great Post.
Thanks.

K.T.
1973 911 E 2.4 MFI
1983 911 SC
1978 911 SC
1965 Devin "D" - 1967 912 Power Plant

CDI unit ...008 or ...001 ?
 

Hello
Please find attached the picture of the CDI unit corresponding to the modified schematics I posted yesterday. The components concerned are indicated.
In particular the diode D8 is situated in the upper left corner, above R12.
BTW I have to confess that I did not pay attention to the box containing this printed circuit. In fact it is not labelled 0.227.200.008, but...001 !

One more model of 0.227.200.001 !http://forums.pelicanparts.com/uploa...1171055448.jpg

I feel dumb as a stump but thanks for this.

Thanks go out to jmchrist for providing corrections and pics of the modified '001' CDI ... most likely done at a Bosch service center or the factory when the unit was sent back for repair. Please note that C13 was changed to a 0.63 uF cap!

Here are a revised schematic of the mod in two versions, one for color inkjet or laser printing, and the B/W version for monochrome lasers:


http://forums.pelicanparts.com/uploa...1182288538.jpg

http://forums.pelicanparts.com/uploa...1182288585.jpg

You can use Irfanview to rotate and save the pic, or print it.