help troubleshooting Parasound A23


I have a Parasound A23 amplifier. It has several relays, can be started by audio signal, 12V trigger or manually. I give this precision just in case.

When plugged to the mains you have a P with red light.
When started you have Two blue lights in front.
You also have a Temp light which is always off.

Now the problem.

Amplifier stays online for several seconds or minute then it can :
A switch off the output and the blue lights
B switch off everything including the red light. In that case you have to unplug from the mains and plug again.

I opened the amp. All fuses are intact. nothing looks burnt.

Dont know what could be the problem or what I shall do.

Any thoughts ?

Regards, Greg.

With the help of profiguy who kindly gave me some troubleshooting advice,
I disconnected the input motherboard and turn the amp on.
After several minutes, something between 1 and 15, it goes off with a relay sound. All fuses are intact.
I don't know if it is a relay problem or if a protection is triggered, but what protection?
Unfortunately it is going to be harder to investigate.

I started to try to understand the principle of the schematics and why would the relay go off.
I understand that there are some DC current feeding relays and other stuff. These components are hooked to a radiator. I started to look at u10 and u5.

So u10,

Amp idle you have 14v ; ground ; 0
Turn amp on : 14v ; ground ; more than 10. This decreases and when goes below 5v amp goes off.

After a while off now showing 8v ; 0 ; 3.5v...weird

Then, is there a problem with that component or is there something counter feeding the output to make voltage lower because of a problem


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I remember when speakers were hooked I was surprised to find 12 ohms sometimes between the two red speakers connectors.

I had a spark at u10, call me stupid.

But amp is still on and sometimes output impedance goes at 2 ohm, then OL on both side. Volt meter or something wrong...
Why doesn't he go off, did I finally smashed the protection circuit u10 ? All voltage are around zero on that one. If it still runs I will try too hook some test gear

Just to keep you posted and for people who encounter a similar problem...
I sold the amp for 200$ to a guy who had not seen the amp and buys defective equipment in order to fix them and make some money.
He told me there was a defective component close to the power supply.
I know that there is now no more support for parasound in France or maybe in Europe.
I sold the working amp and bought a purifi amp from audiophonics. The amp is amazing, very low white noise, very transparent. You can't tell is class d.

Now I have two of them for the mids ans the highs.

Regards, Greg.