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Old 10th December 2012, 05:23 AM   #1
TP143 is offline TP143  United States
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Default Help replacing volume pot

Hi all,

I need to replace the stock volume pot on my Marantz 1122DC. It has a dual round housing on the back end and 8 pins (6 on top and two on bottom) with entensions that mount into the circuit board. I already have a spare Alps volume pot that I would like to use but I have two questions. First, the Alps only has 6 pins. Second, the pins on the Alps are oriented downward facing while the pins (extentions actually) on my current pot are oriented backward facing. Could I use the Alps pot given the concerns above? Would I lose any functionality if two of the pin spots on the circuit board are not connected? Would I run a connector of some sort between the pins and the circuit board?

Thank you!
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Old 10th December 2012, 01:05 PM   #2
rsavas is offline rsavas  Canada
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Did you try getting the original part from Marantz? probably discontinued.
These dual gang stereo volume pots have a tap for the loudness control, that is why there are two extra pins. These are specials, as such very diffcicult to obtain. Try cleaning the original with deoxit. Have to check the resistance and orientation of what the pins are associated with the CW,CCW & wiper terminals.
Peolpe at audiokarma.com , may be able to help you as well.
Rick
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Old 10th December 2012, 02:44 PM   #3
TP143 is offline TP143  United States
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I have cleaned the original with deoxit a few times and I am sure it cannot be any cleaner. Something is wrong with the pot since I continue to get intermittent cutout between both channels. Is it necessary I get a dual bodied pot as a replacement? Is it necessary to have the extra pin connected for the loudness function or if I don't use this function?
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Old 10th December 2012, 03:01 PM   #4
rsavas is offline rsavas  Canada
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The original volume pot is actually two pots, ganged together (dual)
The replacement sounds like it is dual as well since it has 6 leads. You can test this with an ohmeter, outside pins are usually the total resistance, which does not change, middle lead is the wiper, which changes depending on position.
Match the original pot by the resistance value as printed on the body(or measured), these are usually 25 or 50 or 100K ohm nominal types,+/-10 to 20%. Volume pots a logarithmic, so when the pot is turned to half way the resistance is not 1/2 of the total value, it is something like only 30% of the total resistance. So your replacement should be the same (log) taper or it will not work the same as the original. Meaning volume will increase at a higher rate, as you turn clockwise. You want a log type since you want more control at the bottome end, ccw position.
No it is not necesaary to have the taps for the loudness control if you do not use it.

Last edited by rsavas; 10th December 2012 at 03:08 PM.
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Old 10th December 2012, 05:20 PM   #5
Bare is offline Bare  Canada
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radio shack .. even. stocks a 100k alps ganged (stereo) pot with the 2 'extra' lugs for ~$2 IIRC
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Old 11th December 2012, 08:05 PM   #6
TP143 is offline TP143  United States
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I would like to use the Alps if possible. I noticed on the Alps, next to the 6 pins, there are two empty spots with copper inserts (see picture). Does anyone know if these would work if I tapped into them via a connector wire? It is odd that there would be two empty slots.

Click the image to open in full size.
Thanks!
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Old 11th December 2012, 10:27 PM   #7
rsavas is offline rsavas  Canada
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that looks like one they called black beauty, a dual
Use your ohmeter to check it out, there is the total R across 2 pins, usually outside,.cw & ccw
There is the variable R on the wiper terminal, moving between cw & ccw
and for the ones, (tap), there will be an R between tap & cw/ccw pins, total of what is between cw & ccw
looks as if the tap part was optional stuffing of the extra pin.
make sense?
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