Blown injector driver inside Renix ECU

I got BD912 (PNP) this morning, price was approx $1. Put it inside, crossed my fingers and spin it for test with inj. disconnected. Waveform looked great! Same as with original drivers.
Then I connected inj. and immediately noticed that engine is running with all 6 cylinders! Wheeee!!
Took it for a test drive - it drives like brand new Okay, not maybe as brand new, as I have tons of other issues, but it drives much much better with 6 cyls than with 5.

So to summarize, injector output driver, if blown, on RENIX ecu, can be replaced with BD912 or equivalent. It handles 100V, 15amps, and has hFE in 100-200 range (checked with meter, same as original). Note that 15amps is probably overkill, but it should not matter.

Here is table for driver - injector relation.

Q1 - inj. #4
Q2 - inj. #6
Q3 - inj. #5
Q4 - inj. #1
Q5 - inj. #3
Q6 - inj. #2

@5-90,
if you got some time to try, please check if your ecu can be fixed with this method also.

Thank you all for your suggestions, it wall all very helpful!

I'm reading now my first post, and there I made note about welding. Don't know what was I thinking I meant to say soldering. Have no clue about welding, unfortunately, yet.

Thank you - I will definitely have to look into that. Just have to figure out which injector driver is blown on the bare board I've got (the one that came from, oddly enough, South Africa... The RENIX ECU being blown is rare enough - in my experience - that I wanted it!)

That should be easy now to check, when you know which ones to test with multimeter. Just check if there is short between any of B C or E.

It will help if you use soldering iron to heat pins that you plan to test, as bottom side has some protective layer applied that makes it hard to check with multimeter, even if you cannot see it!

mr_W said:

That should be easy now to check, when you know which ones to test with multimeter. Just check if there is short between any of B C or E.

It will help if you use soldering iron to heat pins that you plan to test, as bottom side has some protective layer applied that makes it hard to check with multimeter, even if you cannot see it!

Click to expand...

Yep - fairly common on automotive electronics. It's some variety of shellac, and I'm wondering if it can be readily stripped using something like acetone or MEK (methyl ethyl ketone) - both of which are readily available in hardware stores, for the moment...

great job well done!

Conformal coating is the fancy-pants word. Congrats on getting it fixed. I always feel good when I rescue something from the dump and fix it. Most of the time, it's only a few bucks in parts and some of my time. Then again, I've been known to invest too much time into fixing something worth $10.

But sometimes is the knowledge you gain in this process much more worth than anything else. Yes I saved some cash, but hell now I know a lot more about how these things work!

mr_W said:

But sometimes is the knowledge you gain in this process much more worth than anything else. Yes I saved some cash, but hell now I know a lot more about how these things work!

Click to expand...

Which is precisely why I started the RENIXPower group - groups.yahoo.com/group/RENIXPower. You may want to sign up there and share what you've just learned as well - now that you've sorted it, it could be in a more concise manner - and that's the place where we're trying to figure out how the system was designed and built in the first place!

Dumb question (and I just may not be making the connection here...) but whos part number is "BD912", anyhow? It sounds like it should be more common than the OEM Motorola part, but it would be easier to track down once I know who the number belongs to...

BD912 is manufactured by several companies like SGS-Thomson, Boca, ST, Mospec, etc..
Just look at datasheet http://www.datasheetcatalog.com/datasheets_pdf/B/D/9/1/BD912.shtml

it as as common as widely used BC type (BC107 for example), but BD means for power transistors. Actually, now when I think, this may be true in Europe, but how about US?

good day ) I have the same problem, the computer does not work. make out, there is no visual damage is not, there are also transistors 114-8 in large numbers as they check out? and what exactly do you replace? If you can picture)

KORZHIK said:

good day ) I have the same problem, the computer does not work. make out, there is no visual damage is not, there are also transistors 114-8 in large numbers as they check out? and what exactly do you replace? If you can picture)

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I think you have a different problem - my ECU was fully working, except for just one single injector driver that was busted.

I wouldn't really know where to start if I were in your boots. You can surf to the yahoo renix group and ask there.

If nothing comes up, you should be able to pick one used for cheap.

Thank you! I solved the problem thanks to this thread! changed the transistor(td2) in the photo on the analogue(bd912) and the car started up! ) http://renault-club.by/i/a/ecu-1.jpg

KORZHIK said:

Thank you! I solved the problem thanks to this thread! changed the transistor(td2) in the photo on the analogue(bd912) and the car started up! ) http://renault-club.by/i/a/ecu-1.jpg

Click to expand...

Hello KORZHIK,
info about the renix ecu's is not widdely spread.
However I saw many renix ecu's inside and one of them was a proto type.:clap:
The transistor 114-8 is in fact a TIP110 which is a darlington.
Your ecu worked again with a BD912 but I think it maybe more safe to change it into a TIP110. I did take pictures but cannot post them on this forum because the forum rules prohibit me from posting attachments...:huh:

I just gutted a 1990 XJ RENIX I still all the stuff included harnesses. PM me if anyone is looking. It's from a 5 speed.

protorenix said:

Hello KORZHIK,
info about the renix ecu's is not widdely spread.
However I saw many renix ecu's inside and one of them was a proto type.:clap:
The transistor 114-8 is in fact a TIP110 which is a darlington.
Your ecu worked again with a BD912 but I think it maybe more safe to change it into a TIP110. I did take pictures but cannot post them on this forum because the forum rules prohibit me from posting attachments...:huh:

Click to expand...

You can post a link to the image here using another site for the image location, I think Imageshack dot com is one? Or facebook, just Google free image sites and post there, then post the link here.

Replying to this thread, just had a similar issue on injector 3 (wiring fault caused a short, resulting in the transistor-driver blowing). Here's a shot of the replaced transistor.

http://transistor-man.com/PhotoSet/injector_driver_renix/P1270103.JPG


The BD912 seems to be a great replacement, will report in a month if that continues

Replying back after, three and a half years, the transistor-swap STILL WORKS

Better late than never. Thanks for the follow up!