SVT 3 Pro shuts down UPDATE FIXED

[LarryT]

I have an SVT 3 Pro that sometimes shuts down shortly after I turn it on. Looking at the schematic I see the power-on delay/under voltage and over temp circuits, and that they control the relay that allows output to the speakers. But I can't understand how that circuit would cause power to shut down. Does that section cause power to shut off in an undervoltage/overtemp condition? Or is it's purpose only to disconnect output to the speakers under abnormal conditions? I would like to understand this section before I start troubleshooting the power section. Thanks in advance for any assistance. UPDATE: for anyone interested; found that the power switch hot contact was intermittent. My first clue was the sparking out the front of the switch sometimes. Ordered a new switch and replaced. All good now.

 

[BassmanPaul]

Welcome to TalkBass Larry.

What happens if you switch the amp on without a speaker load connected?

What experience do you have with servicing tube and SS amplifiers?

 

[LarryT]

Thanks for your reply BassmanPaul. I haven't tried it yet without speakers attached. I just obtained schematics this week. I'm a fairly experienced electronics tech. Worked on power supplies, etc, but not audio amp internals. Had theory on tubes in Navy schools, but no real experience with them. Getting ready to start doing some troubleshooting up to my level of competence, before I punt and take it to a shop. I would appreciate any assistance. Specific to some of the questions in my post, when I was looking over the schematic I wondered about the function of the circuits I mentioned.