Auto Power On failure

[leadfootdriver]

My OG Mackie HR 824's are starting to show their age. I bought them new in 98'.

On my left Monitor, the Auto Power On has failed and I'm bummed. I hate that it failed and I hate to manually turn them on and off! LOL

If I set the Rear Switch to On, it comes On. If I switch it to Auto Power while it's on, it will stay on for a couple minutes, but then turn off as if there's no signal.

I haven't opened it up to test yet, but any thoughts would be appreciated.

The Switch is at D-8 on the Schematic. I labeled the input in Red for convenience.

[Jazz P Bass]

The fact that the Auto On function works and then shuts off (mute on) tells me the control circuit works.
You are probably losing the signal that triggers the circuit.
Look at IC 12 pin 7.

[The Dude]

Agree with Jazz- most likely a signal loss issue. Also check C92.

[leadfootdriver]

Thanks for the replies. I did some checking a little while ago. No bulging on any of the electrolytics, but that doesn't mean anything..
I put my meter on a couple test points.
Should these voltages be equal to the input voltage from source??
I highlighted in orange..

[Jazz P Bass]

You need to check for an AC signal at those test points.