Need help to ID this transistor

[stj]

Re: Need help to ID this transistor

so it's an N type device that needs a high base drive - hence the transformer
i bet this turns out to be a fucking ceramic capacitor shorted - it always turns out to be something annoying like that!

btw, forget standard pinouts - they mean nothing if the device is a custom job.

[CapLeaker]

Re: Need help to ID this transistor

strange.

lets see what it connects.
is the screwhole(s) actually connected to the groundplane that the metal case also goes on?

and, does the large track go to any pins on the big connector?

Here is what I get. Yes, the large track where the screws go on for the TO-3 case goes to the GND pins on the connector (orange). The two pins from the TO-3 go also to the connector on the positive (blue). The ground plane on the board isn't always ground, specifically after the connector going to the orange caps!

Watch the pictures if you compare between top, bottom and the one where I was shining a light thorough. It revealed another layer with traces in between.

[stj]

Re: Need help to ID this transistor

about the coating, did you try white spirit on it? i know the plastic on Honda ecu's melts with it.

[CapLeaker]

Re: Need help to ID this transistor

about the coating, did you try white spirit on it? i know the plastic on Honda ecu's melts with it.

Here where I live there is no white Spirit. It's not like Europe where white spirit is readily available. I brought a white spirit cooker with me back then but I have to fuel it with 99% rubbing alcohol around here. I found that the thick hard goo crystallizes under heat (hot air soldering station) then I can scrape it off.

[CapLeaker]

Re: Need help to ID this transistor

Cording to my Leakseeker the short is in between the 2 pins of the TO-3 pads, any further I go, as further I get away from the short. What gives?! I cant find anything wrong, checked all the ceramic caps too. Is there a mad purpose of having these two pads shorted together? For some reason I doubt that this TO-3 thing is a FET. Nothing really fits if I compare my M11 ECU to a N14 ECU in the VGB supply.

[stj]

Re: Need help to ID this transistor

maybe dremel the top off the device - see if it looks like a single gate or something else.

[eccerr0r]

Re: Need help to ID this transistor

If it's a nonstandard part then we can also forget substitution?

Other things... this is "supposed" to be high reliability and I would be very surprised if Mot/Cummins would omit the protective gate zener if that were a MOSFET. That is, if it doesn't have the protective zener inside...

So is it a dead short or how many ohms are you seeing between the pins? If this low resistance was "normal" then it could likely rule out a MOSFET as it would need several volts to hit saturation threshold and the low resistance would thus dissipate a lot of power.

IC Regulator - ruled out?
IC other - ruled out?
Transistor BJT - not ruled out
Transistor MOSFET - possibly ruled out
Transistor IGBT - possibly ruled out
Thyristor SCR - not ruled out?
Thyristor TRIAC - ruled out

For fun:
Left: 2N3055 (NPN-Si)
Middle: 2N1136A (PNP-Ge)
Right: MCR649 (SCR)

All from the days where stamping pinout was not a luxury...

[stj]

Re: Need help to ID this transistor

If it's a nonstandard part then we can also forget substitution?

bullshit.
never surrender!

[CapLeaker]

Re: Need help to ID this transistor

Dead short means a dead short like 0.12 Ohms short.

So I called a company that re manufactures those Cummins ECMs. The answer I got was: "No, I am not telling you what the part is or does" and after I stressed that 828S14 being shorted, "That this is a bad core and want me to get another one". No kidding. Anyway, I guess they are looking for a new ECM now up there. Many thanks to those that tried to help.

[eccerr0r]

Re: Need help to ID this transistor

I'm with stj, it's Dremel time! (with a microscope) To at least figure out what the part is...

and hope it didn't go molten and thus impossible to figure out what it was...

[CapLeaker]

Re: Need help to ID this transistor

It's out of my hands now. :-(

[CapLeaker]

Re: Need help to ID this transistor

Well guys, you won't believe that one, but the boss smacked that ECU back on my bench with another junk ECU. So this thread isn't over quite yet! :-D
Problem right now is that I can't get the covers off the other ECU. Everything is corroded so hard, that whoever took it off, he cut the wires as no one can unplug the plugs.

[CapLeaker]

Re: Need help to ID this transistor

after grinding the case open, it turns out that the ECM is for a N14 again, just like the other one, identical. So back to square one.

[stj]

Re: Need help to ID this transistor

same fault?

[CapLeaker]

Re: Need help to ID this transistor

no, not identical as a fault. I meant identical to the first spare I opened, or as the same as the schematic is for, basically the N14. :-(

[stj]

Re: Need help to ID this transistor

does it have a similar circuit though, possibly with a more conventional TO218 / 220 package

[CapLeaker]

Re: Need help to ID this transistor

Nope, it doesn't. The one for the N14 has a comperator (LM2901) as a gate drive for the Mosfet (MTD3055). The board I am working on doesn't have anything like the LM2901 at the gate. That is my problem. I do not understand how the TO-3 is driven, if it is a mosfet. I've never seen anything like it. For example there is also no 1.8 Ohm 1W resitor to GND, no gate drive resistor etc.

[petehall347]

Re: Need help to ID this transistor

shot in the dark but might be possible to find the circuit designer to ask how it works .. tread carefully and use pr skills to the max ..befriend them . it is far from easy but been there just once . not really but very close .. there will be paperwork documents . its finding copies thats the hard bit . automotive electronics seems to be a closed shop. i gave up on a power steering pump ecu this week and bought a used one . its gone now and i got paid

[redwire]

Re: Need help to ID this transistor

The DC-DC converter for Vgb supply it generates drive voltage for the high-side N-ch. mosfets. The hard part is the DC-DC transformer is on the output and input of the power transistor.

It looks like a self-resonant switcher, for Vgb.
The old model ECM uses discretes and the next gen ECM (Cummins Celect N14) uses LM2901 comparators.

I would sketch out a schematic.

I confirmed the boost-converter is for the diesel fuel rack solenoid.

[CapLeaker]

Re: Need help to ID this transistor

The DC-DC converter for Vgb supply it generates drive voltage for the high-side N-ch. mosfets. The hard part is the DC-DC transformer is on the output and input of the power transistor.

It looks like a self-resonant switcher, for Vgb.
The old model ECM uses discretes and the next gen ECM (Cummins Celect N14) uses LM2901 comparators.

I would sketch out a schematic.

I confirmed the boost-converter is for the diesel fuel rack solenoid.

Maybe you can enlighten me why the 2 pads from the TO-3 are shorted (as a self resonant switcher)? I don't think this is supposed to be like that. However, there is no external diode, or shorted cap that I could find that. So maybe there is a diode internally in the FET?
Making a schematic is out of question, unless I unpopulate the board. The board has at least 3 layers and I am loosing the traces as the go underneath of some IC, cap or whatever.