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.
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.
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.
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.
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.
try searching the internet for a service manual, can be a big help.
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.
Most amps have the mains connected directly to the mains transformer via the mains switch. Any relays are normally in the LT side.
Not that unusual, helps a lot to bring the standby current down to a minimum, but there are other ways of achieving that ofcourse...
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.
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.
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.
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.
I still suspect that as I said in Post #2
Especially if its a dual primary mains transformer.
Does this one have a netfilter? the capacitors in there could be responsible for the shifting reading you get.
Yup, also a possibility especially with older amps. Is the relais sealed or of "open" construction?
OK let me come at this from another angle.
The technics su-g95 that was kicking into overload - I fixed a few days ago had a broken set of solder joints in the little transistors - I believe they are voltage regulators, I opened the thing and there it was easy to spot.
Now on these 3 nothing like that jumped out. But what if one of the transistors (the 3 prongs are collector, emitter and source right, and the signal goes to the emitter, power to the source and the collector is whete the amplified signal comes out right) had a short from source to ground - or whatever the B+ feeds to ground.
Would that not shut it off.
If it was sending b+ to the collector it would not let the speaker protect relay click I think. So its not that.
Thanks.
Srinath.
The technics su-g95 that was kicking into overload - I fixed a few days ago had a broken set of solder joints in the little transistors - I believe they are voltage regulators, I opened the thing and there it was easy to spot.
Now on these 3 nothing like that jumped out. But what if one of the transistors (the 3 prongs are collector, emitter and source right, and the signal goes to the emitter, power to the source and the collector is whete the amplified signal comes out right) had a short from source to ground - or whatever the B+ feeds to ground.
Would that not shut it off.
If it was sending b+ to the collector it would not let the speaker protect relay click I think. So its not that.
Thanks.
Srinath.
The onkyo is "open" cos the cover was broken. The Denon 3802, was "open" cos well, I opened it, and it actually it worked for a few hours after, and then it went into the shutdown thing its doing now.
The contacts are not dirty in those 2. The rx-v795 well I am not sure.
The sony - no idea, I am yet to get into it past pulling the cover.
You guys make me think. I hope I am not bugging you guys with my ignorance.
Cool.
Srinath.
The contacts are not dirty in those 2. The rx-v795 well I am not sure.
The sony - no idea, I am yet to get into it past pulling the cover.
You guys make me think. I hope I am not bugging you guys with my ignorance.
Cool.
Srinath.
Ofcourse you are not bugging me, otherwise I would not post anything 🙂
There are a lot of ways an amp can fail, I really don't have enough info to give you good advice other than the comments I already posted.
There are a lot of ways an amp can fail, I really don't have enough info to give you good advice other than the comments I already posted.
I've just got back from the vets.
Looking at the diagram, the Switched socket is in parallel across the BIG mains transformer as I suggested.
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