Re: 2235 power supply noise


Many thanks for the helpful replies folks.

I just removed R919 and it measured as almost exactly 10K. I don't have any 9.1K or 11K resistors so a put back in a 10K paralleled with a 1M making 9.09K. This didn't change anything.

I don't know what damping substance Tektronix used but I would think that high temperature RTV sealant would be suitable. Do you think I should give this a try?

Holding the probe near T906 I get a very clear waveform with a period of about 48uS which I believe gives a frequency of about 20.8kHz. Obviously that's not the loud audible frequency I can hear though as 20K is too high. However, half that (i.e. about 10,000Hz) would make sense. I just tried playing about with a test tone generator and I estimate the noise the scope is making is indeed about 10,000Hz

I have a frequency counter on my multimeter. Please can someone tell me where best to connect the leads of the multimeter to measure the frequency the HVO.

Thanks, Mike

Join to automatically receive all group messages.