Phono pre-amp problems

I will take a guess. The initial warm up is used to charge a capacitor to the point where it will activate the relay. (There is more to it than that but that is the basics) If that cap is going bad it will leak voiltage when the unit is on and current is being drawn through it. The voltage being supplied to the relay will drop below what is needed to activate the relay (turning the unit off). When the relay opens current isn't flowing allowing the cap to recharge again reaching the specified voltage (turning the unit back on). Then the process repeats itself. This can be a dificult problem to trouble shoot. A physical inspection of the capacitiors may reveal a leaky cap. If not test equipment will be required as there may be more than one cap. It could also be something else but this is a starting point.

Remember to take the system as a whole.

Jsawhitlock, now that you have explained it better, I believe your mute circuit has problem. I never had SF product so I don't know how it is designed. If there is a bad relay for the mute circuit, please go ahead and replace it.

Artizen65, I think you nailed it! Talked to a tech at Sonic Frontiers today and they said the same thing, a cap leaking voltage is most likely the problem. The bad news is no vinyl for about 3 weeks but the good news is that this is not a high cost fix. Any ideas for a cheap phono stage? Cartridge is Benz Glider L2 so I need something with about 55-60 gain.

I hate to even suggest this. Radio Shack used to sell a phono pre for about 25.00 US. If your are looking for a good backup check out Musical Fidelity. I bought mine for 250.00 new.

That 9V battery powered Radio Shack phono pre is actually pretty good. They do still sell it. Battery power makes it pretty quiet.