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

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

Hi Tim, thanks for the reply- there is no problem getting in there, I have
replaced the transformer and output trannies, renewed traces and even added
extra speaker ports on the back thru the years, just it would be nice to
have the pots back working again.

Has switch cleaner got better lately tho? I did try some of that on a couple
of scratchy pots I had 10 years ago, it lasted a short while but the
scratching came back with a vengeance after a while so I deemed it a false
hope and never used any since.

Ad



"Tim Schwartz" wrote in message
...
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

Ad,

I've had good luck with the DeoxIT D5 as I mentioned, often lasting 3-5
years between re-cleaning. Of course pots and switches will last for a
shorter period of time in worse environmental conditions, such as smoke,
dust, cooking, etc. At some point the carbon tracks in the pots can
wear through, and then no amount of cleaning will help.

Regards,
Tim


Mad Ad wrote:

Hi Tim, thanks for the reply- there is no problem getting in there, I have
replaced the transformer and output trannies, renewed traces and even added
extra speaker ports on the back thru the years, just it would be nice to
have the pots back working again.

Has switch cleaner got better lately tho? I did try some of that on a couple
of scratchy pots I had 10 years ago, it lasted a short while but the
scratching came back with a vengeance after a while so I deemed it a false
hope and never used any since.

Ad

"Tim Schwartz" wrote in message
...
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