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nathanscribe
Gold Member
United Kingdom
507 Posts |
 Posted - 02/08/2010 : 16:14:37
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I've noticed a few unusual pot values/tapers/etc in a variety of Boss products, and not all of them are still in production. Does anybody know of a useful source of replacements or of ways to bodge certain things?
I'm thinking particularly of a 1K linear centre-tapped pot. I don't know anywhere that sells cenre-tapped pots any more, and have been straining my brain to think of a suitable kludge. I wondered if it'd be possible to use a 500 Ohm dual pot in some way, but it seems to depend how it needs to be wired. The centre tap goes to a bias voltage, the wiper to a modulation source, and the two ends to the + and - of an op-amp to give +ve and -ve modulation on the one control.
I've already checked with Roland on this - they have no originals or new equivalents. |
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ChristoMephisto
Platinum Member
Canada
1315 Posts |
Posted - 02/08/2010 : 22:31:37
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quote:
Originally posted by nathanscribe
The centre tap goes to a bias voltage, the wiper to a modulation source, and the two ends to the + and - of an op-amp to give +ve and -ve modulation on the one control.
Out of curiosity, what is the pot for?
From what your describing, the pot has four lugs...
is there a wire/lug in the middle of the wiper's track? |
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nathanscribe
Gold Member
United Kingdom
507 Posts |
Posted - 02/09/2010 : 00:38:25
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That's right.
For my own purposes, it's from the PC-2. But they appear every so often. The SP-1 has a dual pot with one normal log and one reverse log track, to give proper balance control, and the PQ-4 uses reverse log dual pots too from what I remember - amongst others. All very well until someone wants a spare part... |
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Laurie
Double Platinum Member
Canada
5682 Posts |
Posted - 02/09/2010 : 01:31:35
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| Spares for nearly all Boss pots are available from Roland. You will need to convince them the part is for a repair - will not supply pots for your own projects. |
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nathanscribe
Gold Member
United Kingdom
507 Posts |
Posted - 02/09/2010 : 14:02:45
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I already sent the part number to Roland with my enquiry but they don't have it. Apparently they don't make an equivalent either - it's the centre tap that's the issue.
I did think it could be got around by using a 500 Ohm dual linear pot with the ends tied together on one end of the sweep,and the other ends tied to the op-amp - but instead of a permanent connection between the mod source and the wiper, add a switch to select which wiper the mod source goes to - and instead of the centre tap, the join between the two tracks could be tied to the bias.
The only clumsiness is the addition of the switch.
My other thought was a standard pot with a couple of resistors in parallel with their centre-point tied to the bias... |
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replacements for odd pots
