Re: Marantz PM310 rotary controls

From: Tim Schwartz (toschwartz_at_worldnet.att.net)
Date: 01/24/05 

Date: Mon, 24 Jan 2005 14:23:35 GMT

MAD,

        FIRST: UNPLUG THE AMP WHEN DOING ANY OF THE FOLLOWING!

        There is a good chance that the pots will clean up with a decent
cleaning/lube spray. I like Caig Labs DeoxIT (tm) D5, part number
D5S-6. This will require you to open the amp up, as the spray needs to
get into the working part of the pot, the the front shaft bearing. If
the unit is really filthy with dust/dirt on the inside, then consider
blasting it out with compressed air, or careful use of a vacuum cleaner.

        The input selector switch may clean up with a spraying as well. In
both cases, use a small amount of spray and work the controls back and
forth many times. DO NOT flood the controls with the stuff! I'm a full
time tech, working on several items a day and a can of this stuff lasts
me at least 6 months, literally hundreds of switches and controls.
DON'T use it on power switches, as it is flammable! Too little is better
than too much. There are many other spray products out there that are
also fine. Read the label!

        As to the broken shaft on the input knob, you can usually cut a small
piece of wood to act as a filler for the missing half. If you need to
glue it in, use a glue that can be removed such as rubber cement or
contact cement so that it can be taken apart if needed for service. As
long as you are gentle when turning the know, it can last for years.

Regards,
Tim Schwartz
Bristol Electronics

        

Mad Ad wrote:
>
> I have an old Marantz PM310 amplifier with all 3 rotary knobs shot, the
> volume, balance and the 3 position click switch.
>
> The vol/bal both have the usual 'microphone swung in the wind' sound of
> crackling and rustling when you turn them and the 3 position switch has one
> spline of the 2 broken so the knob falls off and the contacts are shot
> anyway because you have to fiddle with it to get it to work on both channels
> at once.
>
> Otherwise the amplifier is in fine condition, its has a few bits resoldered
> and renewed over the years but is still giving stirling service as my main
> amp for PC/TV/Music output, except I have to use it via a mixer because all
> the Marantz controls are so bad.
>
> Im guessing that im SOL trying to find replacement controls for it now? That
> 3 position switch looks extremely proprietary and the 2 rotaries are mounted
> in a way that using standard vr pots would not work. The shank is metal and
> much thinner than nylon replacents.
>
> Any ideas please anyone? The unit still has years of life in it, its just id
> like to access the controls without it sounding like a force 10 gale in the
> room.
>
> Thanks a lot
>
> Ad

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