Astley Le Jasper wrote:

My long serving Marantz PM 6010 OSE is ill and before I dump it, I
wondered if it was worth salvaging.

A while ago, one of the channels stopped working. However, when I
plugged a headphone socket in and then out, everything would be fine
for a few months. However, that doesn't work anymore.

Does that give anyone an idea of what's wrong with it?

It's hardly worth taking it to be checked out, because I'll have to
pay someone to look at it ... and might as well get a new amp. It
would be a shame though.

(I've checked it with different sources and also listening using
headphone, but that one channel has definitely gone.)

ALJ

Either the PCB has soldering that is not working or the socket is the shorting kind.

- Resolder by heating up each solder island and removing the soldering iron when the
solder is liquid.

- When the jack is not inserted the socket is shorted so the output goes to your
speakers terminals on the back. When the contact surfaces of the socket get corroded
you get an intermittent connection. Inserting and removing a jack sometimes
temporarily fix this.
What you do not want to do is use WD40 to fix this. You need to clean the contact
surfaces of the socket, especially the parts that short when a jack is not inserted.
For cleaning you can fix the contact surfaces with a proper agent such as Kontakt 60
or equivalent. NOT WD40!

In the event that the socket is defaulty you would replace it with a new one at less
than 2 pounds, but if you do not use the headphone you can solder the jack to have a
permanent connection accros the jack socket, this will render the use of the socket
audible along with the speakers.
If the socket is PCB mounted ad a replacement does not have pins in the right
position simply screw it into the chassis upside down and solder small insulated
leads to the pins from the pcb, most often there is no magic to it except making sure
nothing else shorts the connections - just add a bit of thick adhesive tape if there
is a chance something may short the connections.

-Mikkel