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  1. KJ6EAD

    Wiring Police Light Bar

    Do you have a brand and/or model #?
  2. KJ6EAD

    circuit board testing ?

    Cwb, can you test the bridge rectifier with your diode test? It's the big square thing with four leads mounted vertically next to the - side of the large capacitor. It's marked BR3510L on the top of it's case...
  3. KJ6EAD

    circuit board testing ?

    While most tests were done with the parts on the board, they're isolated by the optocoupler and the motor is disconnected.
  4. KJ6EAD

    circuit board testing ?

    Can you desolder the rectifier and test it again out of circuit?
  5. KJ6EAD

    circuit board testing ?

    The meter has a diode test feature. It's at the left end of the resistance scales and has a diode symbol and a musical note symbol. This feature will apply a voltage to the leads a little higher than the regular resistance settings and it will display the voltage drop through the component...
  6. KJ6EAD

    Repairing RC Hummer - MOSFET replacement

    I'd check the condition of Q15 (driver for FET Q19) also or just replace it.
  7. KJ6EAD

    Name that LCD (AKA Fixing a pile of broken radios)

    Those connectors are designed to be stuck down and soldered once only. If you can manage to release the double stick adhesive completely with a thin blade and adhesive remover first, you'll be able to unsolder from edge to edge in a peeling fashion. A thin wedge of heat resistant silicone or...
  8. KJ6EAD

    circuit board testing ?

    You're getting too many open leads or infinite resistance readings. Can you tell me what meter you're using? Maybe we can find a better test setup.
  9. KJ6EAD

    Old Grundig Valve Radio Sound Problem

    You could be experiencing a condition known as "motorboating". Look it up on Google or in the Radio Museum. It can be caused by something as simple as a leaky bypass capacitor allowing RF into an audio amplifier stage.
  10. KJ6EAD

    circuit board testing ?

    Are you referencing left to right with the components inverted as shown in the last photo? When you say 'no reading' is the meter indicating 0L or what?
  11. KJ6EAD

    circuit board testing ?

    Some of your meter readings don't make sense to me. Are you using the lowest Ohms scale?
  12. KJ6EAD

    circuit board testing ?

    That's pretty much what I expected. It looks like the IGBT is shorted. Can you test the IGBT and the rectifier with the meter leads reversed or just do it again both ways? Your meter doesn't happen to have a diode test feature does it?
  13. KJ6EAD

    circuit board testing ?

    Oh, good. I hoped that was the case.
  14. KJ6EAD

    circuit board testing ?

    :confused: There's no point in asking for advice if you intend to ignore it. Maybe you need to refresh the page to see what you've missed.
  15. KJ6EAD

    circuit board testing ?

    Don't worry about what controls the speed for now. That magnet sensor may just feed the speed/distance on the display. You need to check for shorts like Steve said. I'd start with the IGBT and the rectifier.
  16. KJ6EAD

    circuit board testing ?

    I notice you included a photo of a circuit breaker. Is that the part that trips?
  17. KJ6EAD

    circuit board testing ?

    I'll post some reference data. Toshiba TLP561G Photocoupler Triac Driver (the square thing with six pins) :)...
  18. KJ6EAD

    circuit board testing ?

    Boards are often intentionally produced with parts "missing", technically referred to as unpopulated component locations so this is not by itself cause for alarm unless there's evidence that it was once there and has been desoldered. The designation TVS1 suggests a transient voltage suppressor...
  19. KJ6EAD

    Determining DC adapter

    I don't know. I can't tell from here. My meter leads are too short. ;) Okay, now the serious answer. I don't know. Ordinarily red indicates positive and black negative but sometimes things get reversed. Can you check the polarity of your supply with a meter?
  20. KJ6EAD

    Unique Digital Watch Found

    Your pictures aren't visible. Try posting as .png files.
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