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Topic: Blown Caps in 0-30v 0-10a bench supply repair (Read 4 times) previous topic - next topic

dc42

The 1K resistor looks OK to me, it may be connected in parallel with the diode.

If the diode reads close to zero ohms both ways round using the lowest resistance range of your multimeter, then either it or a capacitor connected in parallel with it is probably shorted. I would unsolder it - should be easy, it's a single-sided PCB - and test it again.
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MAS3

If you are beeping for shorts, always remember how that works.
Most multimeters i have seen yet, beep upon a resistance of 1K or lower.
This means that beeping is more like detecting low resistance than really looking for shorts.
A low resistance could mean a short / defect, but could also mean it's designed that way.

So beeping will give you some idea as to where to look for a short, but will require you to do some closer investigation as to whether you just found a short, or a feature.
You can do this by checking the resistance, eventually taking one side of the component out of the board so you are sure other components have no influence to your test.
Beeping / diode testing probably gives you a reading (millivoltage) on your display, which depends of the type of diode you are testing .
You cannot make any consequenses out of your test if you don't know what the result with that specific part is supposed to be.
So you could ask here what results to expect, stating the exact component type you will be testing.
Or look it up in the component's datasheet.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

dhenry

Quote
these are pos units.


Tell that to those folks who insisted on reverse polarity on your battery, :)

For powering up those unit, the typical approach is to put a light bulb in serial. If the light bulb glows, you have a problem.

smeezekitty



For powering up those unit, the typical approach is to put a light bulb in serial. If the light bulb glows, you have a problem.


I was just about to suggest this. It is called a dim bulb device and I use it all the time for powering up antique and questionable electronics. You can start with a low bulb and slowly go higher.

A small glow should be ok. Lighting up brightly indicates a short.
Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

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