Calling on Motronic experts: IC information

[ischmitz]

I am working on a 3.2 Carrera Motronic and found that one integrated circuit (IC) is most likely bad. Its input is low impedance and straps the injector signal to a fixed value close to GND. As a result the injector output stage does not work. Once I disconnect the input pin (4) of the IC the injector signal produced by the CPU looks normal again. Nice 4.3 msec pulses during cranking like one would expect at R418/R419 The IC is used to drive the injector output darlington transistor T402 and the fly-back circuit Y403/T404. My guess is it must be some type of custom op-amp or similar. It has some resistor network and filter components attached to it.

The part number is 0127 and the date code is 8712. It is a DIP-14 housing with logos from Bosch and Siemens on it.





I understand Bosch while never making their own semiconductors used custom-designed chips made by companies such as InterDesign and had other chips custom-labeled by many suppliers. Is there any recourse to find out a replacement part? What do others do to fix a problem like this?

Thanks,
Ingo

[ischmitz]

Having put some more thoughts into this I came up with more questions:

The 911 3.2 injector configuration is such that all six injectors are wired up in parallel and the injectors are of the peak & hold type with low impedance. Let’s assume the DC resistance of one injector is 2.5 Ohms. This makes the total resistance “seen” by the DME something like 1/R=(1/2.5)*6 or 0.41 Ohm.

Looking at the schematics a little more I expected IC S400 to be a custom peak & hold driver with one negated output for the fly-back control stage. The external timing components and the sense resistor R409 suggest this.

However, with R409 being a 10 Ohm resistor the output stage can not drive more much more than 1 to 1.2 Amperes through the entire injector bank to begin with. At those current levels the resistor alone acts as a perfect current limiter and no peak & hold is required to further reduce the current. What do others think?

Ingo

[dshepp806]

Ingo,

Is signal at ADV13 from the CPU? Assume so,..but don't have prints. It has to be....


As to the 0127,...would there exist an numbers on the front side of "0127"?

[ischmitz]

Doyle,

correct, ADV13 is an output from straight from the CPU. It is active low. When operating properly you would see a +5V with short pulses to zero. It is pulled up to +5 Volts on the digital board. During cranking I saw 4.2msec solid pulses (no PWM) with a frequency of about 10Hz making for 600 injection events per minute during cranking.

I am more and more puzzled by the 10 Ohm resistor in line with the injectors. It seems wrong in many ways and yet the thing is there. I measured it and it is 10 Ohm. See my other post here: http://forums.pelicanparts.com/showthread.php?t=398809

Ingo

[rick-l]

I believe R10 is 0.1 ohm


Edit: I have asked about that chip many times with no response so you might be SOL.

[ischmitz]

Rick, I will measure it one more time tonight. You are right, the way it is named in the schematics it should be 0.1 Ohm. At that level I think I might look into the LM1949 as a potential candidate to do the peak&hold current control. It's design is based around a 0.1 Ohm current sense resistor.

[ischmitz]

OK, my bad - you can all start to call me names. It is indead a 0.1 Ohm resistor. So that makes S400 a peak & hold driver. Now the one-million dollar question is how to find a replacment part. The only thing that I can come up with is the LM1949. Nothing else seems to fit the bill. So my options at this point are to sacrifice a 944 DME or to design a new output stage with the application note coming along with the LM1949. Grrr.

As it so happens we have an eletrical engineer working for us who used to work for Delco when they designed a similar application with a Motorola chip. He was part of the team that spec'd the Motorola chip. Unfortunately, he can not remember any details - much less the chip type they ended up getting...

Any clues out there. I know this information is out there - would some please step up...

Ingo

[Transaxle]

I take this thread up again, since I had the same problem with a 911 ML3.1 box. Still looking for further information about the 0127, I'm wondering if anybody found news in the meantime.

For the schematic: R409 is labled R10 witch is short for 0R10 or 0.10 Ohm. The injector circuit is not connected through ADV13 with the CPU board. Connector ADV12 is used.

S400 and S100 are the only custom chips in a ML3.1. It would be great for the future of our cars if we could find resources for both.

[PcarPhil]

You may want to ask this question in the Bosch Motronic forum over on the Dorkiphus Porsche board:

Bosch Motronic - The Land of NoVA/DC/MD area Porschephiles

[jcge]

Have you looked through the Bosch Semiconductor website/data sheets ?? ( I can't view the pics in your original post from this PC)

Robert Bosch GmbH - Automotive Semiconductors and Sensors

John

[Transaxle]

Great link - thanks!

But I'm afraid that our boxes and chips are a little bit outdated for the actual Bosch development. Anyway - very interesting info on that site...

[ischmitz]

I have searched high and low and this DIP14 is not and was never available anywhere. It is a custom design and Bosch never sold it.

Modern injector drivers are realized with power MOSFET or IGBT stages rather than Darlington BJT. These have much higher conductance and thus less power dissipation issues. Often these stage are integrated into a programmable low-side switch.

[Transaxle]

Looks like both chips are a kind of copy protection for the motronic boxes.

The S100 is a simple wave->square converter for the position mark and the teeth. They added a simple flip-flop to keep the position mark signal up until the cpu can react on it.

Looks like we have to spend a little more time developing replacement circuits for both...

[KeithO]

Guys, it may not be a pin for pin match, but I am sure that it can be replaced with the LM1949 peak and hold injector driver chip.

LM1949 - Injector Drive Controller

The LM1949 is an 8 pin DIP so not sure what the 14 pins are for unless it incorporates some additional circuitry.

The MSEFI injector tester by B&G uses the same chip to drive the injectors under test.

Read about that here. www.bgsoflex.com/FI_tester_doc.pdf

[rick-l]

Originally Posted by KeithO

Guys, it may not be a pin for pin match, but I am sure that it can be replaced with the LM1949 peak and hold injector driver chip.

I think it works more like this preliminary datasheet part from 1988.

L584 Datasheet pdf - MULTIFUNCTION INJECTION INTERFACE - SGS Thomson Microelectronics

The driver in the DME might be a little over designed.

http://forums.pelicanparts.com/3868545-post194.html

I'm not sure this part experiences a high mortality rate.

[ischmitz]

I agree with Rick - the L584 is very similar to the 0127 used in the Motronic. Unfortunately it appears to be discontinued.

At the time IGBJ and PowerMOSFET devices with their extremely low RDsON weren't readily available and that is why Bosch had to go to such extreme in their design. It was to protect the Darlington stage that itself became a necessary design element as the only high-gain switch-like device available at the time.

Keep in mind the 3.2 Motronic drives 6! low-impedance injectors wired in parallel in batch mode. That isn't trivial even by todays standards.

Ingo

[Transaxle]

Great info - thanks for sharing...

It looks like the 0127 was used in all ML1.x boxes too. These are cheap to buy at ebay.

Another point is that this IC seems only to fail in 911 3.2 boxes. Never saw any Porsche 944 or BMW M3 ML 3.1 box with this problem...

[ischmitz]

The IC really only fails when the tachometer gets hooked up wrongly (mostly in 3.2conversions).

The fuel consumption output of the DME comes straight out of the IC. It is the injector pulse width signal. And the tachometer input of a 3.2 tach has an internal pull-up resistor to drive the open-collector tachometer output of the DME. If the fuel consumption line gets hooked up to the wrong tachometer input with the pull-up resistor it drives the IC to full open and kills it in the process.

Ingo

[AlexTRD]

Hello, hoping to revive this thread to resolve a fueling issue on my 88' 924s. The ground side of the injector circuit (pins 14 & 15 @ DME connector) is getting about 10.5v when the DME is supplied power. The harness is good, and this problem still persists when I power the DME on a workbench. I tested the rbdt65a transistor and it seems to be functioning. Pins 14 & 15 seem to be giving the same exact voltage coming from pin 10 of the 0127 IC. Is the IC supposed to be supplying voltage here? Pin 10 on the IC also branches off to a couple capacitors, so I'm thinking either one of those have failed, or its the 0127 IC. I can find no info on this damned chip, so if anyone knows what the function of pin 10 is that would help immensely, thank you.

[T77911S]

I use to do some repairs on BMW computers. it got to where I just did not have the time to keep it up.
I use to rape other DME's to fix others.

I still have some, not sure if any parts are the same.