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Posts uit juni, 2017 weergeven

Denon DHT T100 DESIGNED TO FAIL : bad caps (ceramic caps this time)

A friend gave me a Denon DHT-T100 to look at.
Do not spend much time on it.. ok.


It had a problem, it started clicking and ticking after power on, and after some time.
(a so called intermittent problem)

Sometimes it did not tick or click, but it was basically not usable.
The clicking had a sharp click in one channel and repeated after about a second, then sound recovered and it would click and drop out again.

He told me, do not spend any time on it, yeah, right. ;-) like I would give up after 15 minutes.
I wanted to know what was going on with this thing, I found some schematic online and started measuring the usual things.

The power supply, 24V did it drop down when a tick occurred ? Difficult to find out because sometimes the thing would play for hours without a glitch.

I eventually found out the 24 V PSU, the step down SMPS on board and the LDO's were all ok, all power rails remained within spec, but it still glitched sometimes. (while power was ok)

I investigated methodically,…