On 2/20/2016 11:52 AM, Cursitor Doom wrote:
All noted, thank you, gentlemen. I'll have to check those tips out
tomorrow or a divorce will be in the offing.
Until I report back tomorrow then, thanks...


I managed to find a PM3264 PSU to try out.

Unloaded it squeals as expected so I tried a makeshift load with what I
had lying around, 6 x 470R 5Watt w/w resistors.

You can pull one of the connectors out of the scope for a connection.
(See photos)

Just for fun (and I'm running this off an isolation transformer), pull
V1812 and scope T2 with T1 as probe ground. you should see a nice drive
waveform for a few seconds and you can check the frequency is 20KHz.

Incidentally the core on L1806 on this board was loose (came apart) and
also caused squealing but of a different note.

If you want me to take any readings let me know, nothing too time
consuming though

Photos of load (It gets hot so take care)

https://www.flickr.com/photos/404665.../shares/H24830
https://www.flickr.com/photos/404665.../shares/J18jga