C-1 Problem

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PROTECHGOLF
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C-1 Problem

Post by PROTECHGOLF » Wed Jun 04, 2008 9:06 am

My C-1 has lost volume control, only plays full volume. All other functions are working (I/O's , Hologram, etc.). Any suggestions for possible problem and suggested fix ?

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OBI56
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Re: C-1 Problem

Post by OBI56 » Wed Jun 04, 2008 9:18 am

Hi there Protechgolf and welcome to the forum.

As for your question, the most likely culprit is the actual volume control. If you open the unit up both top and bottom(unplugged naturally), check for anything shorting across the legs of the volume control or you might just have a bad potentiometer. C-1s are notorious around here for having small metal shavings from the screw holes dropping inside, so after cleaning it out, apply a single drop of oil or vaseline to each screw hole before re-assembling. Anything else will require one of the senior technical members to resolve.
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Re: C-1 Problem

Post by RichP714 » Wed Jun 04, 2008 10:01 am

OBI56 wrote:Hi there Protechgolf and welcome to the forum.

As for your question, the most likely culprit is the actual volume control. If you open the unit up both top and bottom(unplugged naturally), check for anything shorting across the legs of the volume control or you might just have a bad potentiometer. C-1s are notorious around here for having small metal shavings from the screw holes dropping inside, so after cleaning it out, apply a single drop of oil or vaseline to each screw hole before re-assembling. Anything else will require one of the senior technical members to resolve.
Obi's right on Protech, and welcome ;)

The screw holes are notorious for shedding screw metal onto the board. A member here recently had cleaned up his pile of shavings, only to have the problem persist... ended up being a single shaving curling around two contact points of one of the switches.
Best to flush the board with some circuit card cleaner spray from radio shack (or similar) It's basically an isopropyl alcohol spray; you don't want a de-greasing spray...too caustic....but isopropyl spray should be cheap and evaporates out of the way. Flush the volume knob too.

Here's what it looks like...I don't remember if the board components are labelled in the C-1
Capture.JPG
Capture.JPG (42.84 KiB) Viewed 1489 times
Once it's flushed out, if you have a multimeter you can (with power OFF) check IC7 pins 2 and 5 for a varying resistance as you turn the dial

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treitz3
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Re: C-1 Problem

Post by treitz3 » Wed Jun 04, 2008 3:46 pm

Hello Protechgolf and welcome to the Carver forum.

Forgive me for what I am about to say please. I don't know how well versed you are with Carver gear or electronics, so hear me out. Are you 100% positive that you have the C-1 hooked up to your amp properly? I could be mistaken, but I believe that there was an output for a processor or something that had only a full output signal. Could you please double check to make sure you have the RCA interconnects leading to the amplifier plugged into IIRCC, the "main1" or "main 2" RCA outputs?
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Re: C-1 Problem

Post by BillD » Wed Jun 04, 2008 4:37 pm

You are right tom. The tape outs or external processor out would do that, but I'm not sure the treble and bass controls would work.
It should sound like it isn't there!
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OBI56
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Re: C-1 Problem

Post by OBI56 » Wed Jun 04, 2008 6:44 pm

The problem here seems to be that it will only play at FULL volume no matter where the volume control is set, not that it plays at half volume or with no sound at all. Treitz is correct to check that your connections are OK because I now remember having that happen once with my C-2 when I accidentally hooked the power amp to the Tape Monitor outputs after changing all of my interconnects. Scared the crap out of me!!!
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Re: C-1 Problem

Post by TNRabbit » Wed Jun 04, 2008 6:47 pm

treitz3 wrote:Hello Protechgolf and welcome to the Carver forum.

Forgive me for what I am about to say please. I don't know how well versed you are with Carver gear or electronics, so hear me out. Are you 100% positive that you have the C-1 hooked up to your amp properly? I could be mistaken, but I believe that there was an output for a processor or something that had only a full output signal. Could you please double check to make sure you have the RCA interconnects leading to the amplifier plugged into IIRCC, the "main1" or "main 2" RCA outputs?
Good call to both Tom & Marc; you will only do this ONCE!! I believe this might possibly be your problem.... :shock: :shock: :shock: :lol: :lol: :lol: :lol: :lol:
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Robert R
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Re: C-1 Problem

Post by Robert R » Tue Aug 05, 2008 6:58 pm

If Holography works, you are not "monitoring" the tape monitor outputs - those a ahead of the main volume control and are not affected by it, nor do they have any holography signals. Likewise the Ext. Proc.
With unit unplugged, ohm-check for chassis ground at volume control - you may have a broken foil or a crapped-out control. If it's grounded but doesn't reduce the volume, it's shot internally, one must suppose.
Does the balance control work?

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Re: C-1 Problem

Post by BillD » Tue Aug 05, 2008 7:58 pm

Good point Robert. If holography works, it's past the tape monitor and external processor loops. Here is a schematic that RichP provided in another thread showing the volume controls. There is only one opamp involved w/o any controls engaged and I think it's a 4136.Image
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
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Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer

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