Alfa Pages

[sportston]

DOES ANYBODY HAVE AN ECU FOR SALE FOR A 33 1.7IE OR A 1.5IE? tHIS IS FOR A BOSCH MOTRONIC 3.1 SYSTEM
mINE ISN'T SENDING THE IGNITION SIGNAL ON ONE OF THE SIDES OF THE COIL PACK.
PLEASE HELP!
I'M LOST WITHOUT MY BABY TO DRIVE. ITS THE ONLY PLEASURE I GET THESE DAYS.

[ZeNiTh-PbArM]

ugh

i did not have a look at one of those ECUs but from what i recollect ignition transistors inside the ECU are quite easy to replace. they are often bipolar low-side darlingtons. any TV repair shop should be able to locate a replacement part.
i often used standard TO220-packaged NPNs or IGBTs for such a job, cost around 1.5$ and easy to find (easier than your ECU i think).
but beware : transistor failure has not happened out of nothing ; shorted coil wiring will fry the transistor, as well as disconnecting HT leads with engine running. be sure to repair any other failures before inserting a good ECU.

regards,
zp

[sportston]

Thats very interesting. I am a little underskilled in that field however. I'll open the box again and see if I can have a bash though. Now who did I lend my soldering iron to?

[sportston]

I'm still trying to find the cause of the blowout. I know it must have been my fault forgetting to disconnect the battery before removing gearbox. But what shorted precisely I'm not sure of.

[sportston]

must be alzheimers!

[ZeNiTh-PbArM]

hi,

you must have knocked something near the coils, as they are prone to bump in the upper engine mount when lowering the gearbox. you also may have caused a short in the harness (check continuity with ohmmeter between coil supply and coil command wires, ECU and coil unplugged : you shall find high impedance)
besides, how did you check there is no output signal? did you swap coil wires at the connector?

to repair ECU, power stages are often clipped onto a heatsink, any TV repair shop will be able to have a look at your ECU and tell you what has gone wrong.

regards,
zp

[sportston]

You want to know how I checked it all out?
OK this is the bit where I look really stooopid.
I am a fully qualified Crypton Approved Technician (engine tuner and diagnostic bloke) retired. I checked out the wave form using the free run time base on the oscilloscope of my ancient and barnacle encrusted crypton machine (purchased for £6.50 from ebay!). The two signal outputs revealed only one wave form instead of two.
So now I feel really stupid for making a silly mistake and forgetting to detach the earth lead....on my own car! Why oh why did I not turn brain on before engaging body?
What lesson can you learn from this?
Don't get too cocky. Professionals do make mistakes. I'm starting to think I'm getting too old and my brain is turning to mush. I keep forgetting thigs.
I keep forgettting things, like how to spell.
And sometimes I keep forgetting things too.

[sportston]

I forgot to ask about how to repair it. I'm afraid my electronic knowledge is limited to schoolboy GCSE course. I remember that transistors are a method of switching and a darlington pair is where one transistor is connected to another and one switches the other as a way of stepping the current. I seem to remember they are little black things with three legs and look like a semicircle roughly. I also remember what their symbol on an electrical diagram looks like. I have to admit however that I have never replaced one and can probably count on one hand the amount of times I have ever installed any (again at school).
Anyway just to confirm that bipolar means on or off and never in-between yes?
And "low side"? meaning low voltage and before the main switching circuit? which in this case is in the separate module under the bonnet above the coil pack and mounted on the same bracket.

[sportston]

I've had a look inside the box and I can see one round/semicircle transistor and I think the big black flat square things with a heat sink are transistors too. Am I right? There are 5 up against the heat sink (4 with three legs and 1 with 6 legs) there are also two elswhere on the PCB with three legs. That makes a total of eight when you add the roundish one.
How sure are you that it is a transistor that needs replacing?
How do I test one?
I have a multimeter and an oscilloscope as you already know.
How do I know which one does what?

[sportston]

I've been looking in the RS catalogueAccording to the picture they look like TO220 . But I seem to have some trouble working out which to get. I've found some numbers on the side of my ones but they don't seem to correlate with anything.
several bear this mark:-
PH
ON588
m 9233
another this one:-
PH
ON588
m 9302
and one more
this is the one with 7 (not 6 as I wrote earlier) pins:-
siemens
30191
9248

I would assume it would be one of these square upright ones. But which and what?
Any advice would be gratefully recieved. Thanks for a point in the right direction so far.
I've just noticed that it is a doublesided PCB. But I can't see any transistors on the other side anyway.

[sportston]

and there is one more i forgot to mention that I cannot see the numbers on unless I removed it.

[ZeNiTh-PbArM]

hi

i think a few pics would help a lot
as you have two ignition outputs i would suggest you find 2 similar transistors
try to swap them and see if the dead ouput changes. if yes you found the culprit.
then i can suggest a replacement part

regards,
zp

[sportston]

Ok so I've removed the two I suspect to be the ignition ones but managed to break a leg off in the process! Whoopsie daisies! I think I can make it fit anyway by soldering the stump. ...Just incase you were wondering it was one of the legs on the transistor I broke, not mine.
I was just curious; How do you check a transistor to find out if it works and what type it is etc.?
As you already know I have a multimeter and a Crypton 335 with 316 interface at my disposal. But no one has ever taught me how to check diodes with them before. Is it possible? I guess it must be!
How I wish i'd taken more notice of my GCSE electronics text books several years ago! Must bone up! I think I have a teach yourself electronics book somewhere.
I'm quite looking forward to learning more, even if I do bugger up my ecu its fun to experiment (as long as it isn't on someone elses car).
cheers now.
I'll be back soon to give the next progress report.
Tomb

[stedee]

funny enough i work with electronics to check diodes you need to put voltage through it,it should either allow it to travel one way only but others work a bit differently like allowing a set ammount of voltage to travel backwards ,transistors are gates but you need to know the correct voltage to open the gates to test them
i dont know how much stuff is in there but its rarely diodes or resistors that break unless something else as gone to make them go - you could look for swollen capacitors especially the electrolytic type - cylindrical shape - if the top is bulging out they are gone but chips seem to be the weakest link.
if you want to try replacing some components i would get them you as
i deal with those comps all the time and i could get them easy and free most of the time
_________________
brum brum

[sportston]

I just happened to find a place that shows how to test transistors out and explained a bit. I have duly done so to about 4 of the things on my ecu and all gave near exactly the same readings (these are all the same type 0N588 etc.) I think I'm a bit closer but still scratching my head!
readings are as follows
B to C = 2.3-2.6m ohms (flows one way only with B connected to + lead of multimeter)
B to E = 5.5-6k ohms (flows both ways)
C to E = 2.3-2.6m ohms (flows one way only with E connected to + lead)
These are readings obtained with them REMOVED from the PCB.
From this I guess that my transistors are ok? or were, until I removed them breaking off one or two pins along the way. I've also checked every diode I can find (round black things with a silver ring on one end that only allow juice through one way, yes?)and they seem to be working too.
I've checked all the other transistors and they seem ok as far as I can tell.
I'm beginning to wonder if I'm nearing the end of my capabilities?

[sportston]

Ok there isn't one cylindrical shaped capacitor on it! There are several rectangular red ones (all of which pass a visual inspection) and three green blobby ones. How do I test them?

[sportston]

So its 1:30 in the morning and I'm still fiddling with electronics! Yawn getting tired..

[sportston]

I've checked the green blobby ones and am getting some continuity through them but with varying resistances. And the same with all the red ones too. And there are two green rectangle shaped ones. They too are the same.
Process of elimination would seem to indicate a blown chip? Or am I wrong in assuming this?

[sportston]

of course there are about a million resistors on the PCB too......
No NO NOOOO please don't make me check them all!!!
I can see the headline now>>>
"A 93 year old Essex man was found dead at his home yesterday in Burnham-on-Crouch. Police thought they had found the first case of a real ilfe bionic man when they saw that the man had wires from an electronic testing device grafted to his hands. The medical examiner said he had never seen anything like it and that they must have slowly been integrated into the flesh during non-stop use."

[ZeNiTh-PbArM]

hi

if all power semiconductors look well, re-assemble the ECU and put it on the car. i dunno how you tested the transistors but i would still guess it is a dead transistor as those are prone to failure if harness is shorted.
charge the battery and have someone crank the engine
at the same time, use your scope to check for ignition signal in the ECU
follow the tracks on the PCB and the components until you find coil trigger signal again ; this will locate the culprit.

regards,
zp

[stedee]

you are brave - by the way if a resistor is knackered they usually have a burn mark on them - i will check the ecu for you today if i can
steve
_________________
brum brum

[sportston]

no burn marks. can't reassemble ecu due to damaging a transistor!

[stedee]

i habe had a look for those tranny part nos but cant find anything they are probably obselete.anything that isnt widely used in the electronics industry becomes obselete very quickly
it a shame if i new the values for the tranny you could probably get a repacement but obviously that aint happening.
steve
dont give up
_________________
brum brum

[ZeNiTh-PbArM]

hi

characteristics for transistor is not hard to guess.
for ignition something like IRGS14C40 will fit
for injectors i often use BDX53

regards,
zp

[sportston]

Thanks for the info as to what may do the job transistor wise. But I still have to find the problem even if I buy new transistors. So I guess I may be looking for a faulty chip.