Strange preamp fault

I was testing the system downstairs today and realised that the new turntable was only playing in the left channel, just like the old sherwood one started doing.

So I connected the turntable via another pre-amp and it worked fine. So I gather the preamp section of the Marantz pM4000 has failed, does anybody have any idea what may have caused this as I am worried the same thing might happen to my PM6010OSE

 

I think we will need a few more details to be able to give you any help.

 

check for garlic bread in the right ear
could be 101 things, plug a good i/c into the phono input . touch the center pin olny of the phono plug on the other end of the i/c,turn the volume up a bit see if you get a nice hum,try wiggiling the plug aroud see if make the hum disapeer.

 

I took the top off, I looked at the design at there appears to be capacitors on the pre amp section, I think either one of these has gone, as sometimes the right channel works and sometimes it dosn't. It works fine with the turntable feeded through the sony reciever, however its not good the keeping the signal path short.

 

Are the input sockets soldered directly to the p.c.b? could be a dodgy conection,or cracked circuit board what makes you think a capacitors gone? i assume the line level inputs work fine?have you checked for garlic bread?

 

Yeah the level inputs work fine, my dad said he was listening to the turntbale the other day and it was making a horrible noise but didn't really desbribe it but he said it kept going quite, although this may have just been a dodgy record. There is nothing spilt in it, and the amp inside looks pretty much like new, apart from dust. I may clean the whole thing tomorrow and spray and some PCB cleaner on some of the contacts.

I suspect the capacitor as when you switch the amp on from cold it works fine, its only when you have played it for about an hour the right channel just cuts out.

 

best bet is to get some freezer spray ,let the unit warm up until the fault happens then spray each component until it starts working again,a circuit diagram will be usefull so you can work out wot to freeze.

 

eh???how do you know its the pre-amp bit, just caus the sherwood....if it cuts out it could well be the protection circuitry or a relay, or god knows what...
sorry I have read it properly now...does the rest of the amp work ok on other sources, then yes I think you can trace it to the phono stage...

 

The sherwood turntbale quickly went back to the shop. I have a slightly better Yamaha one now. Its still not great but it plays LPS for my parents, and its ten times better than the cheap £50 bran new TT's you can buy.