alps 6 ch motorized pot help wanted

glorocks · 06:30 AM

I purchased 2 alps RK16818MG pots, and when connected according to the spec sheet, they do not attenuate audio. They are marked "AC only", and as you would expect, I can't measure any resistance with a DVM.
When connected, they pass audio but don't act like potentiometers.
Anybody out there with any experience or ideas? The website is just about useless. ANY help appreciated--
These were purchased on Ebay from a German concern, so my pleas for help from the vendor may not net much info.

jackand08 · 22nd June 2010, 06:32 AM

It would help to see a simple diagram as to how you've connected the pots. By the sounds of it, if it's not attenuating audio, then you may simply have them incorrectly wired. Have a look at this article here about wiring pots correctly. Also, the `DC only` that you read probably refers to the motor on the pot and means that it will not operate with AC - therefore, DC only.

glorocks · 22nd June 2010, 03:58 PM

Thanks, however I can't seem to find a link to the article you refer to. The DC only for the pot motor makes sense.
I just got a better diagram from the vendor, but it matches the factory drawing. I'm going to try connecting again when I get to the shop this evening. I'll get back with you later and send the diagram.
J-

jackand08 · 22nd June 2010, 04:01 PM

Here's the link again: ESP - Potentiometers (Beginner's Guide)

A diagram would help greatly and should make solving your problem much easier

.

glorocks · 23rd June 2010, 12:47 AM

Hey- Thanks for your help. I got a clearer hook-up diagram from the vendor, and the device is now acting like a volume control.
What threw me is the "AC only" tag (I may have said DC). I can't get a resistance measurement using a VOM or DVM, but it does attenuate an AC signal.
The other quirk I noticed is at signal levels above about 2.5 VRMS, the top half of a sine waveform squares at settings below about 50%, and the squaring worsens as the "pot" is turned down. So it looks like I may have to add some gain in the next stage to get my target output of 10VRMS.
Whatever is going on in there is certainly not a resistor.
For some reason I can't attach the .pdf file of the hook-up diagram with this browser, but if anyone is interested I can provide it from my home machine.
Again, Thanks

glorocks · 23rd June 2010, 12:53 AM

By the way, the circuit is a remote volume/mute circuit I designed for 7.1 surround system that buffers the output from my PC and converts the output to 600 ohm balanced out to feed my EQ, limiters and power amps, all of which are balanced in and out.

Enzo · 23rd June 2010, 04:19 AM

It would be real helpful if we knew what you were measuring? "Can't get a resistance reading," doesn;t specify what you are measuring. You can't measure resistance across the resistive elements or between the wiper and element? or you can;t measure resistance at the motor terminals?

And I went to Alps web site and entered that number (RK16818MG), and they have no record of that part number. Is that an Alps number, perhaps a typo, or is that a part number from a supplier like Mouser or Digikey or someone. I would like to look up the data sheet.

22nd June 2010, 06:25 AM	#1
glorocks diyAudio Member Join Date: Jul 2007	alps 6 ch motorized pot help wanted I purchased 2 alps RK16818MG pots, and when connected according to the spec sheet, they do not attenuate audio. They are marked "AC only", and as you would expect, I can't measure any resistance with a DVM. When connected, they pass audio but don't act like potentiometers. Anybody out there with any experience or ideas? The website is just about useless. ANY help appreciated-- These were purchased on Ebay from a German concern, so my pleas for help from the vendor may not net much info. Last edited by glorocks; 22nd June 2010 at 06:30 AM.

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22nd June 2010, 06:32 AM	#2
jackand08 diyAudio Member Join Date: Oct 2008 Location: England	It would help to see a simple diagram as to how you've connected the pots. By the sounds of it, if it's not attenuating audio, then you may simply have them incorrectly wired. Have a look at this article here about wiring pots correctly. Also, the `DC only` that you read probably refers to the motor on the pot and means that it will not operate with AC - therefore, DC only.

22nd June 2010, 03:58 PM	#3
glorocks diyAudio Member Join Date: Jul 2007	Thanks, however I can't seem to find a link to the article you refer to. The DC only for the pot motor makes sense. I just got a better diagram from the vendor, but it matches the factory drawing. I'm going to try connecting again when I get to the shop this evening. I'll get back with you later and send the diagram. J-

22nd June 2010, 04:01 PM	#4
jackand08 diyAudio Member Join Date: Oct 2008 Location: England	Here's the link again: ESP - Potentiometers (Beginner's Guide) A diagram would help greatly and should make solving your problem much easier .

23rd June 2010, 12:47 AM	#5
glorocks diyAudio Member Join Date: Jul 2007	Hey- Thanks for your help. I got a clearer hook-up diagram from the vendor, and the device is now acting like a volume control. What threw me is the "AC only" tag (I may have said DC). I can't get a resistance measurement using a VOM or DVM, but it does attenuate an AC signal. The other quirk I noticed is at signal levels above about 2.5 VRMS, the top half of a sine waveform squares at settings below about 50%, and the squaring worsens as the "pot" is turned down. So it looks like I may have to add some gain in the next stage to get my target output of 10VRMS. Whatever is going on in there is certainly not a resistor. For some reason I can't attach the .pdf file of the hook-up diagram with this browser, but if anyone is interested I can provide it from my home machine. Again, Thanks

23rd June 2010, 12:53 AM	#6
glorocks diyAudio Member Join Date: Jul 2007	By the way, the circuit is a remote volume/mute circuit I designed for 7.1 surround system that buffers the output from my PC and converts the output to 600 ohm balanced out to feed my EQ, limiters and power amps, all of which are balanced in and out.

23rd June 2010, 04:19 AM	#7
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	It would be real helpful if we knew what you were measuring? "Can't get a resistance reading," doesn;t specify what you are measuring. You can't measure resistance across the resistive elements or between the wiper and element? or you can;t measure resistance at the motor terminals? And I went to Alps web site and entered that number (RK16818MG), and they have no record of that part number. Is that an Alps number, perhaps a typo, or is that a part number from a supplier like Mouser or Digikey or someone. I would like to look up the data sheet.