HP-1940 2STB

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  • Francesc V.
    Onkyo A8200 - Not the right voltages in some transistors
    by Francesc V.
    Hi:

    I am trying to repair this amplifier that I've bought as faulty. I've found some transistors damaged, the ones where I am drawing a red circle.

    With the final transistors not yet installed (the expensive ones), I've started to measure some voltages:

    Where I am supposed to have 1.12V (base Q524/Q523) I am reading -42V..................both channels don't seem ok.
    Where I am supposed to have -1.12V (base Q526/Q525) I am reading -44V..................both channels don't seem ok.
    I removed and tested Q514,Q516 & Q513,Q515 but the analyzer...
    04-19-2025, 07:17 AM
  • redbaron1007
    Sundown SFB-8000D What are these transistors?
    by redbaron1007
    I had a Sundown SFB-8000D amp come into the shop yesterday that wasn't giving any output. The guy who brought it in said he bought it off some crack head on Facebook marketplace for a good price, but bought it knowing it was broken. Apparently the original owner was cutting out the transistors to the right of the ones pictured whenever one would blow and take the output out. Best I can figure he also cut the legs on the S5 and S6 ic's as well and soldered them back together.

    My problem is Sundown decided in the factory to remove the original markings on the IC's and now I can't figure...
    11-12-2023, 07:30 PM
  • Bob Wong
    MSI Crosshair 15 A11UEK. Need help with Transistors!!!
    by Bob Wong
    Welcome badcaps, repairing a Crosshair 15, in need of transistor specifics. Received a broken laptop that's was perfect for repair, threw away the looser transistors in a haste... Should and could have salvaged them.
    In any case, I will be posting all my discoveries to this forum as a thanks in advance. Thanks in advance lol.

    P.S. If anyone is familiar with such things, as in, If anyone knows that MSI uses one or one of a few types of transistors when marked with a number please let me know how I can find more specifics before I start throwing hail marys.
    03-15-2025, 02:02 PM
  • hyva_ana
    Marantz PM-66SE Burns Transistors
    by hyva_ana
    Hello,

    While ago I replaced those big filter caps to that amplifier. After that started to happen. I connected the amplifier normally to the mains and almost immediately several transistors burned out. I really didn't do anything else (at least on purpose) than replaced those big caps C801 and C802.

    After that I replaced those burned transistors (I can't remember exactly what they were) and measured all the others, and now everything should be ok. But, when I power up that amplifier part with two bench power supplies connected in series there is obviously still something...
    02-11-2023, 06:34 AM
  • vbogoev
    GYSMI 160p welder transistors shorted
    by vbogoev
    Hello,

    Here I have GYSMI 160p welder with no output. Otherwise the machine is starting, the fan is spinning, but the output is zero... I disassembled the welder and found the problem. 3 out of 6 transistors are shorted, and 3 pairs of 4 resistors are burned... There's also 1 burned "ultra fast diod" on another board that is connected to the transformer. My question is how can I identify these burned resistors, I have no idea what value they should be, also I am not able to find any image of the board over the internet... The other part numbers are clearly visible, so I...
    08-31-2023, 03:53 PM
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