Should there be connectivity between the 2 prongs of the switched outlet

[srinath]

I have a few amps that shut down instantly after I turn em on.
I was working on one, a yamaha rx-v795 and after testing a bunch of things, I tried to check the resistance between the 2 outlet prongs on the back of the amp in the switched outlet and I got a steady 6 ohm.

I cant imagine it is correct. I think the 2 prongs are not supposed to be connected to each other. Anyone know ?

Thanks.
Srinath.

[KatieandDad]

The switched outlet will be in common with the Primary of the Mains Transformer.

[srinath]

I thought the relay needs to be "switched on" for that.
I thought when you push the on off switch you activate the power supply relay, which switches on the switched outlets and the power to the main transformer.

In this amp that "switching on" lasts for all of a fraction of a second. Then it switches off. Regardless of whether its "switched on" or not I have connectivity between positive and negative prongs on the switched outlets.

Thanks.
Srinath.

[Mark.Clappers]

No, probably there's only 1 relay in there switching the mains transformer and the switched outlet. This is probably powered by a small secondary transformer (used as power supply for the stanby circuit).

try searching the internet for a service manual, can be a big help.

[KatieandDad]

That would be unusual but I am not familiar with this amp.

Most amps have the mains connected directly to the mains transformer via the mains switch. Any relays are normally in the LT side.

[Mark.Clappers]

Not that unusual, helps a lot to bring the standby current down to a minimum, but there are other ways of achieving that ofcourse...

[srinath]

Yes 1 relay powered by a 12v trafo the size of a shot glass. That one is working.
It makes 12v, the relay switch activates everything lights up an instant and goes dark.

I have this same thing happen in 4 amps. I have found 1 manual for one of those, the onkyo TX ds 555 which I got with a blown up switching relay. It had no top cover or any way to switch itself on. I forced the prongs together first for an instant ... only to see a very faint light in the display, and nothing else. I put it aside in favor of one that I got before anyone got in it.
That brings me to the rx-v 795, I cannot see how a 6 ohm reading between the outlet when the amp is off can be even OK. I will test some others and post back.

Thanks.
Srinath.

[srinath]

OK the working sony 333 - which has a problem but in the outputs, not where it shuts off right away, has a constantly shifting reading, anywhere from 100 ohm to 5 ohm, constantly changing.
The Denon 3802 which is doing the same shut down right after start up where I pulled the trafo and the face panel and everything, shows open. I didn't measure it before yanking everything out, and the onkyo 555 is also too far apart to measure this without near full reassembly.

Thanks.
Srinath.

[Mark.Clappers]

This 6 Ohm can very well be the DC resistance of the primary of the mains transformer..

[KatieandDad]

Originally Posted by Mark.Clappers

This 6 Ohm can very well be the DC resistance of the primary of the mains transformer..

I still suspect that as I said in Post #2

Especially if its a dual primary mains transformer.