Author Topic: burned led

January 03, 2021, 09:49:02 pm
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jyt

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Hi just build the CP4500, ready to test, so far so good, plugin the my extender like i normally do with all my build, once i power it up i notice that the led on the meter goes on right away, no big deal perhaps, i start testing all the points like normal procedure, all report correct, then i push the in button, green led flashes an guess what burn out right away, i tested and notice that i get -16v on the negative led of the led, the led of the meter are not burned but they are always on tho! any idea where is my problem?

January 04, 2021, 04:25:11 pm
Reply #1

JPK

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The current limiter in the LED's are the relays and resistors R104 & R105.
Check that diodes D19 and D20 are not reversed.
Check the value of  R104 & R105.
Check you don't have a short circuit between some pins of CN2a & CN2b.
Check there is no mistake in the wiring of the meter.
JPK

January 13, 2021, 09:24:25 pm
Reply #2

jyt

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hi, sorry but so far i did not figure out the problem, all seem ok, but here what questioning me about, on the meter itself does the blue and red short be shorted, cause taken it on the open the meter and i have a short between those two. it is not coming from the connector

January 13, 2021, 09:43:05 pm
Reply #3

jyt

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ok i fixed too, it was a short inside the meter itself, pretty delicate, so i still have to wait till a get a new led before i can put it together for calibration.

February 07, 2021, 02:55:23 pm
Reply #4

Dolbah

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ok i fixed too, it was a short inside the meter itself, pretty delicate, so i still have to wait till a get a new led before i can put it together for calibration.
My LED burns out too. But i do not have a short between any of the meter wires.
Have you reach a conclusion to your problem yet?

February 08, 2021, 11:08:35 am
Reply #5

JPK

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You can temporarily replace the led by a short.
Was the meter shorted from the start?
Did you repair the meter by opening the back or the front?
« Last Edit: February 08, 2021, 11:11:36 am by JPK »
JPK

February 09, 2021, 03:35:33 pm
Reply #6

jyt

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You can temporarily replace the led by a short.
Was the meter shorted from the start?
Did you repair the meter by opening the back or the front?
Yes it is fix and ready to calibrate, just going to do it real soon, waiting for the LED.

Here how I did it. I had to basically open the whole thing, taken the black front frame, don't try to unscrew the middle big screw, that is only for adjusting the vu needle. Cutting the securing transparent tape slowly around the meter, open it, then I open the back also since I was not certain where was the short, careful about how the small leds and wire for it, it following a specific path, you will need to put it back the same way. Then I was able to see the short, the cables inside are very fragile, tiny, so I had to do it carefully, I de-soldered the wires and added some heat shrink tubes to protect the connection. put it back together and tested, no more short.

February 09, 2021, 03:45:55 pm
Reply #7

JPK

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Than you jyt!
JPK