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1755350 No.1755350 [Reply] [Original] [archived.moe]

I am repairing a bass amp and can't figure out this pot. The others are linear 100k pots, but one labeled "mifld freq" is a c100k inverse log pot. The others all have 3 pins but this one has 7. It is exactly as pictured.

1 through 4 and connected by a trace on the board. 5 and 6 are wired separately and 7 is unused.

I would like to replace the pot with a regular 100k linear pot. I don't mind if the adjustment curve changes, but is this possible? Please help. Thanks everyone.

>> No.1755360

>>1755350
Going to a linear pot wont be okay. A little imperceptible wiggle of your finger will be the difference between too soft and too loud.

>> No.1755385

>>1755350
What a bullshit part.

The only thing I can think of would be to use a digital potentiometer chip, and control it accordingly to get the inverse log curve. If you hooked it up to a digital encoder, at least it would probably last forever with that horrible scratchy noise on that oem carbon deposition pot.

>> No.1755389

>>1755385
>control it accordingly
Dude log digital pots exist. There's a good reason for their existence. Quit whining and use the correct part, this is not some extinct tech.

>> No.1755397
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1755397

>>1755389
> log pots exist
Obviously.
This one ain't that common. I guess you have a big bin of them though.

>> No.1756036

>>1755350
No need to get snippy,
If I understand your description correctly, the first 4 pins of the potentiometer are connected together.
That means that the potentiometer is only connected in 3 different places which means it can probably
be replaced with a generic 3 wire part. From the picture you provided connecting the first 4 pins together
doesn't make much sense but connecting the last 4 pins would allow the third track to be used as input, and
the second track is connected to your pins 6 and 3 which would be your outputs.

>> No.1756567

>>1756036
Hey op here sorry man but I haven't posted since the original post, I don't know who was being snippy but it wasn't me! Lol

But if you connect the last 4 pins together then pin 6 isn't independently available.... And advice how to wire this with a regular 3 wire pot? My thinking was the same, there's only 3 connections to the board since 1-4 are connected but I can't figure it out... I wired one side of a regular pot to where the 4 pins were together, and then the middle to where pin 5 went and the other side to where pin 6 went .... No dice.... Sorry to be a dumbass, I don't really understand what's going on the way it was wired!

I know with a linear pot the adjustment curve won't be the same but at least it would work.... I don't know why this weird pot is being used.... :( Please help guys it would mean A LOT

>> No.1756568
File: 114 KB, 1080x1798, received_167159044606243.jpg [View same] [iqdb] [saucenao] [google] [report]
1756568

Gratuitous photo of broken pot for attention =P

>> No.1756787

>>1756568
Could you post a picture of the traces underneath? What happened when you substituted a 3 wire pot? You said that pin 6 isn't individually available, what do you mean by that? The way you tried to wire it up sounds reasonable, maybe its some other combination of pins where the middle is not pin 5.

>> No.1757259
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1757259

Here ya go thanks again

Someone suggested that it might make sense to jump the last 4 pins but that would include pin 6

When I put a 3 wire pot nothing happened.

Can anybody explain what is happening with this weird pot? What is it doing? I will post the diagram as well

>> No.1757261
File: 743 KB, 1080x1920, Screenshot_20200124-100202.png [View same] [iqdb] [saucenao] [google] [report]
1757261

>> No.1757304

>>1757261
That looks like the pot is actually two pots opposing each other (R32A & R32B). I don't understand your goal of replacing it with a different part unless you want to redesign your active tone stack.

>> No.1757313

>>1757304
That weird bullshit pot is like copy protection, it's hard to clone it directly in China because it's unnecessarily custom.

If only they hadn't cheaped out on it and made it sub-Chinese 10 yuan-store quality, and made it nearly impossible for legitimate owners to fix.

Bose has been Chinese knock off quality for more than 20 years now.

A Chinese knock off would probably use an standard dual gang pot, ironically of higher quality.

>> No.1757479

>>1757313
Yesssss this exactly.
>>1757304
The whole point is to replace these with panel mount pots that won't shatter the first time you bump into a knob

But if it's a mono amp why the fuck does it use a dual pot and why is it wired that way I can't make sense of it.

>> No.1757486

>>1757479
>But if it's a mono amp why the fuck does it use a dual pot and why is it wired that way I can't make sense of it.
Is it a mono amp though? From what I looked at, it's part of some system and the amp is housed in the sub enclosure.

>> No.1757495

>>1757479
It's part of the tone circuit. It probably shifts the frequency center of the mid boost. You could replace it with a dual gang.

>> No.1757918

>>1757486
It's a mono bass amp 100%

>>1757495
This is exactly what it does... How would I wire a regular dual pot? No way to use a single?

>> No.1757940

>>1757918
>How would I wire a regular dual pot?
Follow the traces and see what pin of the opamps they go to. Center pin is that arrow on the center of the resistor that it goes to.
>No way to use a single?
Not really.

>> No.1758109

>>1757918
sure just hook it up. Whatever.

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