Marantz PM6004 repair

A super chap called Richard from work collared me

"I've got a Marantz amp, intermittent low volume on the left hand channel, usually when changing between speakers A and B , and it only happens on one set of speakers..it's too good to throw out. Can you take a look?"

Yeah ... why not?

 Nice looking modern amp...

 ... and very nicely constructed.

 We're going to have to get the main board out, which is a bit of a struggle as usual, as all the sockets are connected straight to the main board. But before that, let's see if the amp will misbehave for us... Yep, one of the speaker protection relay's doesn't always make it across. They're only rated to 5 amps, which seems a little low for my liking, so some 10 amp relays are obtained, and fitted.

 Here are the guilty parties. Actually only one was faulty, but I changed both to be on the safe side. A check of the bias (it was fine) and a good soak test. An easy fix.








When I returned the amp, the guy said it had always done this since new, and had been returned under warranty twice. Each time it was returned stating "no fault found". I would have thought it was obvious, once the customer's speakers and wiring were eliminated from the equation...