Source for replacement caps in H744 regulators

Jon Elson elson at
Thu Jan 6 20:39:07 CST 2022

On 1/6/22 6:04 PM, Matt Burke via cctalk wrote:
> Quiet regulator:
> Noisy regulator:
> The yellow trace is the emitter of Q2 (input of L1) and the cyan trace
> is the output of L1. Q2 seems to be switching partly on then fully on in
> the noisy regulator. it should of course be fully on or fully off as
> seen on the quiet regulator. Also the switching frequency seems to be lower.
Yes, the 2nd unit is running at 5 KHz, clearly explaining 
the noise.  Possibly there is a bad flyback diode, or 
something causing the different waveform.


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