Problems with old Marantz PM57 amp

[admin_exported]

I have an old Marantz PM57 amp which must be about twelve years old now. When I first turn it on the sound I get through my speakers is crackly and fuzzy. After about ten minutes this disapears and the sound is fine. I have changed both speakers and speaker cable and the issue has continued hence why I figure the problem is with the amp. Before I buy a new amp does anyone know of anything specific that might be causing this and/or could it be easily fixed or is it more likely that something is amiss and I need to replace my amp?

 

[noogle]

Could be a dry joint problem that goes away as the amp warms up? There are lots of independent engineers who could probably fix this kind of thing, but given the value of the amp it wouldn't be worth it. If you really like the sound, buy another on the 'Bay.

 

[Anonymous]

I have come across this problem before. It was caused by bad contacts in the selector switch and ribbon cables from the volume control pcb to the main board. Simply cleaning them cured it. However, there is also the fact that the electrolytic capacitors in the circuits and power supply are 12 years old, these can dry out with various problems and should be replaced before any real harm occurs.

 

[Mooly]

Is it just one channel that is affected or both ? All inputs or just one ?

It's just remotely possible that this problem could be caused by tarnished contacts in the speaker "output protection/muting" relays assuming it uses them. If you turn it up loud and then back down again is it any better ?

 

[Anonymous]

Both channels are affected but it effects the left speaker more than the right. it happens across all inputs as well. I have to turn it up loud originally to be able to hear anything.

Thanks for all your information. Seemingly it could be fixed but would cost similar to a new amp.

 

[Mooly]

Does sound a bit unusual tbh... both channels affected. If you felt confident doing so (and all usual safety warnings apply) then it might be worth taking the top off and having a tap around with it on and see if anything shows. Beyond a "dry joint" that could be re-soldered or the relays (tap them) your options are limited I'm afraid.

It almost certainly is easily fixable, and the problem is probably quite minor... if you're into diy then you could always post it up over at diyAudio.com

Is it distorted on headhones ?

 

[Mooly]

 

[Anonymous]

I haven't tried it with headphones so can't be sure but I would have thought it would be the same. I was thinking of upgrading anyway so maybe this is a message that i was right.