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-   -   Grundig 2540U Volume Problem (http://www.videokarma.org/showthread.php?t=252365)

relaximus 10-14-2011 02:34 PM

Grundig 2540U Volume Problem
 
The volume pot on my newly acquired Grundig has a problem. I've Deox'd it, yet it still does not lower the radio's volume properly. It looks to have a capacitor attached to it. The pot has dual, concentric knobs: 1 for volume and the other for tone. Could this cap possibly be used for the volume control?

Another question: Has anyone ever used Radio Daze restoration services?

Thanks!
Dave

VintagePC 10-15-2011 10:21 AM

Usually the cap is attached to a fourth (center of the carbon track) lug on the volume control to give the pot logarithmic behaviour when turned - this gives a more even volume change as you turn the control.

Reece 10-16-2011 09:49 AM

I don't have the schematic for your radio, but here's my 2 cents: with a concentric control, the center knob controls the rear pot, the outer knob controls the front (closest to panel) pot. In most volume wiring, when the volume is turned down the wiper of the control approaches a terminal which is at ground or close to ground potential which helps to kill the volume (the volume is also reduced because the wiper is farther from the other terminal which supplies the audio signal.) Looking at the control from the rear with the center terminal of the three pointing at 12 o'clock, the "ground" terminal would be the one pointing at 11 o'clock. Check the schematic and see if the 11 o'clock control is connected properly with respect to ground. Hope this is not far off!


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