Need help to ID this transistor

[redwire]

Re: Need help to ID this transistor

It may be basically an Armstrong oscillator, like used in Joule thieves and Tesla coils etc.

I'm suggesting a partial schematic, rough scribblings. I don't know what the case connects to, or the two shorted pins- do they go to GND or case. Totally blind as far as even the pinout of this mystery transistor.
Try measure inductance between the two pins, that will tell you if it's merely a transformer winding we are seeing.

The only other reasons for a short there are melted pcb inner-layer, or a shorted speed-up driver.

[CapLeaker]

Re: Need help to ID this transistor

O.k. that looks similar to what I see. It also uses a gate to source diode. That diode should be by right's very close to the FET. That would explain the short, or even a shorted ceramic cap. Now this is where things have me going. No shorts anything surrounding that area. Quite a few posts back on this thread, I did take that transformer out and the short persisted. However I just measured the 2 pads and I got 0.3uH inductance, same as if I short the leads. I also had discovered that there was a 3rd layer on the board. That layer is impossible to trace, since it is covered up and blocked from big fat traces on the either side of the board. As far as installing a replacement FET with a different case style, I am thinking to gut the TO-3 and use it to mount a TO-220 or whatever on that. So close, but yet still so far away. Ugh.

[eccerr0r]

Re: Need help to ID this transistor

Ah so you did find a gate to source zener diode after all? That was the tell tale sign for a "professionally created" mosfet circuit... tells which pins are source and gate...

Now if that were a schottky diode...

[CapLeaker]

Re: Need help to ID this transistor

No, there should be a diode but coun't find that sucker yet. It should be close to the FET, but I have almost all smd stuff through on that board and no shorts anywhere. Even if I go with my Leakseeker 89, I always get back to the 2 pads of the TO-3. So almost as the short is intended to be there. At that point, I don't understand the whole thing.
I did check the mosfet on the newer board, in which the schematic is for and there is no short between the gate and source pin. Unless someone can explain to me how this circuit is supposed to work with the gate to source pads shorted, I am going mad soon.

[redwire]

Re: Need help to ID this transistor

The only other way, risky, to ID the short... if there's no other inductors/transformers it could be cause (low R reading)...

I'd inject the two pads with a bench PSU set very low voltage say 0.3V and 0.5A. So "something" is getting power through it and will heat up. A thermal camera you can spot the short right away, even on less power.

It's strange the PCB has these two pins shorted AND the removed transistor has these two pins shorted. Coincidence?

[CapLeaker]

Re: Need help to ID this transistor

I may have to do that this way. I have to see a FET yet that is o.k. with 2 pins shorted?

[juano777]

Re: Need help to ID this transistor

hi any conclution about this? i have the same problem whit that ecu

[CapLeaker]

Re: Need help to ID this transistor

A short between the 2 pins on the TO-3 FET?

[Nick2k]

Re: Need help to ID this transistor

Here is the info plus some other information in PDF But I believe it is for a different model ecm

Thanks

[Nick2k]

Re: Need help to ID this transistor

A short between the 2 pins on the TO-3 FET?

Hi there,
I know it is an old thread but it may help someone.
828S14 is not a FET it is a heavy duty fast recovery surge protection diode.
Both pins are shorted and measures like a diode from body to any Pin
as long as it is not shorted between body and pins its all good.

Also on PCB there is a track shorting these two pins and going to little transformer.
Thanks

[redwire]

Re: Need help to ID this transistor

All the TO-3 diodes are dual except for power zeners. Are you sure?
Microsemi has 50W zener in TO-3 package with the two pins shorted, and either polarity available. Example Microsemi 1N2816A 18V 50W, standard polarity; anode is case.

[CapLeaker]

Re: Need help to ID this transistor

Unfortunately at that time there was absolutely no reference available on what that 828S14 supposed to be. And I believe there is still no reference to this thing available, which makes it absolutely useless.

[On2ItDan]

Re: Need help to ID this transistor

Hi Guys
Sorry for posting in this older thread but it does relate. This has been a good read regarding the Celect series controls

I have got one on the bench at the moment that will not power up. THer is no 5v supply at all. Have replaced the electro capacitors as these fell off due to vibration and age also replaced some open circuit resistors.

I have found that there is an SOT-23 packaged device that connects to the small transformer and the 67S01 device. I have circled the area in the attached pictures. THe device is difficult to ID as there is a hole in it. Plus I can not find data on the 67S01.

Can someone help to identify the SOT-23 device even if its just marking codes of a good unit we are trying to avoid buying new as theis is an expensive controller.

Thanks in advance
Daniel