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    #21
    Re: Need help to ID this transistor

    Originally posted by redwire View Post
    This (fake?) website teases with Cummins Celect ECU schematic but I couldn't download it. To at least find out what the part is.

    The big black donut is a potted toroid inductor for the boost-converter.

    I wonder if carefully hacksawing the lid off the TO-3 would reveal any die markings?
    I found this: https://www.slideshare.net/HugoNelso...-63-dschematic
    and one can see all 5 pages, but I still can't read anything. I can't DL that file on that link you posted either. Die markings.... maybe worth a shot.

    Originally posted by stj View Post
    russian search engine works well
    start here:
    http://garageforum.org/Thread-Cummins-Schematics
    That's what I saw at the shop, but it doesn't show the internals of the ECM.

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      #22
      Re: Need help to ID this transistor

      so that gets this:
      (interesting that it's designed by Motorola!)
      Attached Files

      Comment


        #23
        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
        Attached Files

        Comment


          #24
          Re: Need help to ID this transistor

          Originally posted by stj View Post
          so that gets this:
          (interesting that it's designed by Motorola!)
          Thanks stj! Yes, that's on that link. But the resolution sucks so bad that I can't really read it. Yes, there are a bunch of Motorola IC's in there.

          I think the part I am looking for is on page 4, top left, VGB supply. In the middle of that schematic part is a transformer and a MOSFET.

          So this would account for then for the unit not to power up anything, no dash light's etc.

          Comment


            #25
            Re: Need help to ID this transistor

            Originally posted by R_J View Post
            Here is the info plus some other information in PDF But I believe it is for a different model ecm
            R_J and stj, you guys are great!

            R_J, there are similarities between those two ECM's. Look at the Cummins N14 Celect ECM digramm (your second upload from top). The VGB supply on page 4 top left. They do have a different part number though, then what I took out.

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              #26
              Re: Need help to ID this transistor

              The second file I uploaded should be the one you want. I was going to upload it earlier but I could'nt see that transistor number anywhere in the schematic
              Last edited by R_J; 05-27-2017, 02:12 PM.

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                #27
                Re: Need help to ID this transistor

                Originally posted by R_J View Post
                The second file I uploaded should be the one you want. I was going to upload it earlier but I couldn't see that transistor number anywhere in the schematic
                Q311 MTD3055EL. They got rid of the TO-3 style FET in your schematic. Problem is that the gate drive IC (IC300 LM2901D in your schematic, a different Motorola IC in mine) may be shot too, since the TO-3 is shorted across the pins.
                Last edited by CapLeaker; 05-27-2017, 03:04 PM.

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                  #28
                  Re: Need help to ID this transistor

                  That's a help, sheet 4 shows the "Vgb" and "boost" supply. At least you can see the main sections. It's all quad-comparators and op-amps for the driver in this sch.

                  I'm stuck on the TO-3/TO-204 pinout, doesn't match any (MOSFET/BJT) part I can find. What am I missing in the pic? Means this custom part has a flipped pinout?
                  Attached Files

                  Comment


                    #29
                    Re: Need help to ID this transistor

                    I've thought on the same pin out. There is something else I don't understand.
                    There is a dead short between the D and G pads. So I removed that green SMD resistor marked 2211 going from that G pad and I still have a short. It should be a total open. So there must be a third layer on that board.

                    Comment


                      #30
                      Re: Need help to ID this transistor

                      There is at least one more layer if not another one on that board. So we are talking 3 or 4 layers on that board. They don't made that easy.

                      Comment


                        #31
                        Re: Need help to ID this transistor

                        Are there any more connection hints under the glued white insulator on the top side of the board? Or is it silkscreen ?

                        Comment


                          #32
                          Re: Need help to ID this transistor

                          yea rip that pad off.
                          i would fit any replacement with a low-profile heatsink anyway.

                          Comment


                            #33
                            Re: Need help to ID this transistor

                            The gate connects to other stuff besides the 2211 resistor. I'd guess a nearby SOT-23. I think it's 4-layer pcb.

                            I use needle-probe or dental pick with an alligator lead to my multimeter, to poke through the conformal coating without cracking parts.

                            Comment


                              #34
                              Re: Need help to ID this transistor

                              This is what I on top with the heat pad removed and a flash light shining on the back side of the board.
                              redwire: problem is that I have a dead short of 0.12 Ohms between those two TO-3 pins with that 2211 resistor removed. So there must be another trace going from that pad somewhere else which I can't figure out due to other components being in the way. All TO-220 style packages are O.k. No shorts on any of the bigger stuff. Any surrounding SOT-23 hasn't have any shorts either. So I thought maybe there is a Schottky diode across those pads creating that short (but this doesn't make any sense to me either), but couldn't find anything else shorted yet.

                              stj: Yeah... I thought on that, but with all the vibrations in a big rig, I am a bit skeptic about things falling apart inside after a while.
                              Attached Files
                              Last edited by CapLeaker; 05-28-2017, 05:27 PM.

                              Comment


                                #35
                                Re: Need help to ID this transistor

                                There seem to be relatively thick traces from both of these pins. Not clear which one would be gate, source, base, emitter etc. Could it be that the component is driven directly from the little transformer nearby, so you are measuring the transformer winding?
                                Attached Files
                                Last edited by paulstef; 05-28-2017, 05:44 PM.

                                Comment


                                  #36
                                  Re: Need help to ID this transistor

                                  i did wonder same thing . maybe test from transformer pins or remove transformer to see . it could still be something else though if removing transformer gets rid of the short . do those schematics not match your board ? i havent looked as low on internet credits at moment .

                                  Comment


                                    #37
                                    Re: Need help to ID this transistor

                                    pull the transformer.
                                    i have seen transformers like that used to boost gate-drive current in crt stuff.

                                    Comment


                                      #38
                                      Re: Need help to ID this transistor

                                      The more I look at that layout I'm more and more confused. Usually the thick wires are power/GND and TO-3's if looking from the bottom and pins rotated towards the "bottom" it'd be Source/Emitter on the left and Gate/Base on the right. Case is always Drain/Collector.

                                      Perhaps I should go to the local pick&pull and buy a module from them to study... (I wish I had schematics to my Chrysler RE42's TCU as it too failed in some odd way.)

                                      Supposedly the big/case connection is either drain or collector, what is this immediately connected to?

                                      Is what's supposedly source/emitter connected to GND?

                                      My guess is that 2211 SMD (2210 ohm?) resistor is not actually the base drive and just sucking off the GND connection. The buried connection is the source/emitter (I HATE THIS for multiple reasons and hope this isn't the way it was made). Then the base/gate is connected to the transformer with this wicked thick track...? This would be the only way for the wiring to make sense unless that device has a nonstandard pinout?

                                      Comment


                                        #39
                                        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?

                                        Comment


                                          #40
                                          Re: Need help to ID this transistor

                                          Originally posted by paulstef View Post
                                          There seem to be relatively thick traces from both of these pins. Not clear which one would be gate, source, base, emitter etc. Could it be that the component is driven directly from the little transformer nearby, so you are measuring the transformer winding?
                                          I did take that little transformer out and the short on those TO-3 pins persists.

                                          Originally posted by petehall347 View Post
                                          i did wonder same thing . maybe test from transformer pins or remove transformer to see . it could still be something else though if removing transformer gets rid of the short . do those schematics not match your board ? i havent looked as low on internet credits at moment .
                                          No. The schematic is for a Cummins Celect Plus (N14). The board I am working on is for the Cummins Celect (M11).

                                          Originally posted by stj View Post
                                          pull the transformer.
                                          i have seen transformers like that used to boost gate-drive current in crt stuff.
                                          Did that and short between those pads is still there.

                                          Originally posted by eccerr0r View Post
                                          The more I look at that layout I'm more and more confused. Usually the thick wires are power/GND and TO-3's if looking from the bottom and pins rotated towards the "bottom" it'd be Source/Emitter on the left and Gate/Base on the right. Case is always Drain/Collector.

                                          Perhaps I should go to the local pick&pull and buy a module from them to study... (I wish I had schematics to my Chrysler RE42's TCU as it too failed in some odd way.)

                                          Supposedly the big/case connection is either drain or collector, what is this immediately connected to?

                                          Is what's supposedly source/emitter connected to GND?

                                          My guess is that 2211 SMD (2210 ohm?) resistor is not actually the base drive and just sucking off the GND connection. The buried connection is the source/emitter (I HATE THIS for multiple reasons and hope this isn't the way it was made). Then the base/gate is connected to the transformer with this wicked thick track...? This would be the only way for the wiring to make sense unless that device has a nonstandard pinout?
                                          There is no local pick and pull for big rigs around here unfortunately. The big case connection seems to be on the GND pins (09,28, etc.) on connector C. Also the case connection of the TO-3 does not go to the little transformer. I see the big track going underneath Connector C, thats it. The two pins from the TO-3 however do go to the transformer. The last picture in this post Where the flash glare is, that's where the little transformer was. You see the track that basically goes from one side of the transformer to the other, and then ends up on the negative of the first capacitor at the connector.


                                          Again first picture is supposed to be for the Celect Plus (N14) in which case the schematic is supposed to be for, but not the one we are working on!!!
                                          Attached Files

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