Hi-Fi Problem

[74merc]

Hi,

I thought I would ask around here since there is a lot of hi-fi/electronics expertise. I've got a Primare A20 amp which seems to be switching itself off and on repeatedly. It sounds like a relay is opening and closing and whenever it is open, no sound comes out of the speakers. I have had it checked in the workshop of the shop where I bought it and they found no problem. I also checked it in their demo room and it behaved perfectly. The problem appears more frequently when the amp or the room is cold. Anybody any ideas?

Martin

 

[television]

First unplug any thing that is plugged into it, the relay that you can hear is there to protect the loudspeakers from any DC that my be present on the loudspeaker terminals, as any DC will knock the tweeters straight out.

Now if there is any DC present from what ever you have plugged in to the rear , this can work its way through to the output stage, and shut it down.

The worst offenders are CD players that Have a D/A converter like the Arcam Alpha series. I have one here now that when its cold it turns off the main amp.
Hope this helps

 

[verytalldave]

Could of course just be something very simple like a dodgy/intermitant fuse of maybe even the mains plug connection with the wall socket. Possible if the problem didnt happen elsewhere. Clean the plug pins and/or try in another wall socket.
Or another possiblity is a bad LS connection or even a continuity break within a connecting cable.
It really is a process of elimination - replace all bits piece by piece until the offending item is found.
Loudspeaker cables/connections are a common source of problems.

 

[74merc]

Thanks for the replies. I've checked a number of things already. Replaced the internal fuse, tried different speaker cable, speakers and sources. I think my CD player might have something to do with it though. Sometimes it just generates white noise, sometimes no noise. It's a Primare D20 and I believe the model has been problematic in general. Verytalldave, what is a LS connection?

 

[television]

Could of course just be something very simple like a dodgy/intermitant fuse of maybe even the mains plug connection with the wall socket. Possible if the problem didnt happen elsewhere. Clean the plug pins and/or try in another wall socket.
Or another possiblity is a bad LS connection or even a continuity break within a connecting cable.

Sorry to have say there are only 2 fuses in it, and I have never had a faulty one yet. If it was the mains plug the lamp would go off on the front as well.

A faulty loudspeaker lead will not turn off the protection circuit, the current is going the opposite way. A faulty inter connect would just cause the sound to drop out on that ch

 

[television]

The white noise shows that there is a fault in the D/A converter in the CD unit, as I said if you run the amp with it unplugged it will prove the point

 

[verytalldave]

LS = loudspeaker

 

[74merc]

I tried disconnecting all the inputs and the problem is still there. I noticed there was a grounding post on the back of the amp so I ran a lead to earth it. It helped a bit but the problem still persisted. Ironically when I bought the gear, I had my choices narrowed down to 2, Primare and Musical Fidelity but chose Primare as someone told me that MF electronics are unreliable. Thankfully I still have my trusty 20 year old Arcam Alpha to stand in and to be honest is almost as good.

 

[television]

This shows that the fault is within the amp if it cuts with nothing in the RCA jacks. this could be anything from a little off set from either channel to a component breaking down. we put a very sensitive volt meter to the output and there should be no more than 10mv of DC.

Shame that you are so far away as I could fix it for you