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Old 14th December 2010, 12:07 AM   #11
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Thank's Mooly,
The problem is, all the 7 channel using 1 pot rod and motorized, so if I replace 1 of the pot, I must replace all and to make it worse the part is not available...
How about using transistor as buffer to limit the current across the pot?
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Old 14th December 2010, 01:09 AM   #12
tomchr is online now tomchr  United States
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Replacing the pot with another logarithmic/audio taper stereo pot is by far the easiest solution. The Alps pots are quite nice.

If you insist on using a digital solution, I suggest that you replace the pot with an encoder, use a volume control IC (like the Texas Instruments PGA2320) and use a micro controller to read the encoder and control the volume control IC.

~Tom
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Old 14th December 2010, 06:16 AM   #13
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by Gunawan W View Post
Thank's Mooly,
The problem is, all the 7 channel using 1 pot rod and motorized, so if I replace 1 of the pot, I must replace all and to make it worse the part is not available...
How about using transistor as buffer to limit the current across the pot?
If there are 7 separate gangs to the pot... and that's how it reads... then with the greatest respect I do not think you realise how difficult and complex this would be. You would never match the characteristics of an LDR/or Digital arrangement to the others.

Post a picture of it all... and the make and model
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Old 14th December 2010, 01:39 PM   #14
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Quote:
Originally Posted by Gunawan W View Post
Hi Mooly,
I don't know how much current...
I only knew that the right channel was broken, maybe it was because my daughter turn it at max at one time when I turn it it on... the amp is 100 watt per channel.

thank's
Are you sure it is the pot and not the right channel amp? What are the symptoms that make you think the pot is broken?
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Old 15th December 2010, 01:31 AM   #15
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From the description of the failure mode, I too doubt that the problem is the pot.
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Old 15th December 2010, 07:08 AM   #16
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Hi Mooly,
it is Yamaha DSP A-970, I can't take picture, because the unit still at my friend.
Hi Bob,
yes it is broken, I already tested it.
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Old 15th December 2010, 07:13 AM   #17
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You can buy a ladder type attenuator kit. It has a pot option: a PIC reads pot's positions and translates it in decibel steps. A stereo ladder attenuator with 4 switchable inputs costs around $50. One of advantages is precision tracking between channels.

Click the image to open in full size.
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Last edited by Wavebourn; 15th December 2010 at 07:15 AM.
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Old 15th December 2010, 07:22 AM   #18
Mooly is offline Mooly  United Kingdom
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Nothing to suggest really... I think trying to source a replacement is the only viable option.
With the greatest respsect do you realise how big a task trying to integrate something like a totally different control system into a commercial product is ? What about maintaining remote volume operation from the same handset... yes it's all do able but it's a monumental task.

It would help to see picture of this thing (the pot). How many gangs etc. Have you tried Yamaha direct for spares... in different countries ? Similar models that use the same pot ?
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Old 15th December 2010, 08:17 AM   #19
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It's really quite easy. Pic any AVR, PIC, etc with an analogue input. A few lines of code and a simple interface to any number of the many available electronic pots. All in a day's work and voila Provided, of course, your time is free and you have some basic knowledge of microcontrollers.
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Old 15th December 2010, 10:46 AM   #20
farjon is offline farjon  Brazil
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What about this?

audioPT - Pré-amplificador audioPT 1

You can translate it on Google.
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