VW Eurovan ECM - part id help!!!!

[willb]

I am trying to help someone out with the repair of a vintage 1992 VW Eurovan engine computer. I have found a bad transistor which tests as a diode on my Atlas DCA55. It is made by Motorola, in a package I have not seen before (I mainly repair commercial audio equipment), and has markings of 104 and 112. I believe 112 is the PN however I can not 100% identify this part. I know Motorola (Onsemi) makes the TIP112, but there is also a J112 Fet out there, and the MJD112 (which seems to be a TIP112 in a different package). If anybody can shed some light on the part that would be amazing!

Thanks!!!

[Manul]

I would vote for MJD112. But I would test it more first, you cannot always trust automatic tester, especially because if it is MJD112, it is not a simple transistor, but a darlington with integrated diode and some biasing resistors.

[esepecesito]

No idea of what it is, but you can check the pinout: the metal pad mus be connected with the collector or the drain, check if that is consistent with the datasheet of the part you will try.
Also use a tester with diode testing, and try to find out what diodes are still alive (if any) and also check if that is consistent with the replacement.

[fzabkar]

MJD112 seems to fit the package and application.

See pages 437 and 438:

https://mirrorservice.org/sites/www.bitsavers.org/components/motorola/_dataBooks/1994_Motorola_Semiconductor_Master_Selection_Guide.pdf
https://mirrorservice.org/sites/www.bitsavers.org/components/motorola/_dataBooks/

[esepecesito]

Yeah. Pretty much. If you want to be sure do the test (middle pin and slug) they should be connected, both collector.
Also other test you can do (to make sure there will be no smoke) is test that the emmiter (3) pin is GND in the PCB. And the base --pin1-- (when still transistor is not placed) the voltage is not greater than say 5V other so.