Message
Re: P-9 making high pitched sound
2018-12-12 by man.of.mystery@ntlworld.com
I guess it could be a buzzing transformer, but I wasn't aware that could give a high pitched sound.
I don't know if this helps, but there appear to have been three different versions of the power supply:
https://www.muffwiggler.com/forum/viewtopic.php?t=27314&sid=88d7c9202a1c15c9911203676478376e
If it's a mechanical noise, you might still get it with all modules unplugged, or failing that with just a dummy load, e.g. a small torch that can take 12V, connected to a bus board. If so, it would have to be the power supply.
- Andy