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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

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Old 16th Oct 2017, 11:50 am   #121
OldTechFan96
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Default Re: Scopex 4D-25 Oscilloscope Repair Help

The transformer is outputting the AC voltages is should. The resistance between one side of the transformer to the other(yellow to pink 2) is 1.359K ohms. I'll discount it as a possible source of trouble and focus on the -20V section of the power supply.
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Old 16th Oct 2017, 5:05 pm   #122
karesz*
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Default Re: Scopex 4D-25 Oscilloscope Repair Help

Hello,
HTML Code:
If there is a short to ground:
it can be such capacitor or (if has it) a tantalum...
Regards, Karl
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Old Yesterday, 4:05 pm   #123
OldTechFan96
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Default Re: Scopex 4D-25 Oscilloscope Repair Help

I have replaced TR683, TR684 and TR681 with BC212s as two of them tested bad. The voltage on the negative end of C684 is too high at -27V. I heard a fizz like sound and shut off the scope. There was a burning smell which I'm sure came from the transformer.

I'd like to do more voltage testing but I'm concerned about damaging other parts of the scope or burning out the transformer. It's a shame as I've just bought a sweep generator.
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