Peavey Nashville 212 power supply question.

[Londonx]

Hello, this is my first time posting, so please be kind I have a Peavey Nashville 212 and have a question about the +-15 power supply circuit. What is the purpose of R54 (700 ohm 5 watt) on the input of the positive 15 regulator (U6)? Why only on the positive regulator and not the negative regulator? I'll try and upload the schematic. Thanks

[x-pro]

This resistor was installed later, when debugging the circuit,
when the device whistled when turned off. That is why it has such a position index - R54.
Capacitors at the input of on-chip stabilizers are rather large in nominal value.
And not only the amplifier chips are powered from +15 V, but also the control switch on U6. Here it is de-energized earlier by a sharp discharge of the capacitor at the input of 7815.
Also, a quick disconnect of 7815 disables Q7 on input U3, putting the latter in MUTE mode

[Jazz P Bass]

Well thank you X-Pro for that tidbit.

[Londonx]

Thank you X-Pro for the explanation, it was driving me nuts. I appreciate the reply.