Thread: Low volume
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Old 03-25-2009, 03:01 AM
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radio63 radio63 is offline
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Join Date: Oct 2005
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The data on Nostalgia Air is very helpful if you don't have a hard copy of the schematic in front of you. However, I would measure the resistance as I had mentioned earlier, by disconnecting one of the leads of each section from the circuit.

Here's some additional info from my notes of 20 some odd years back, voltages I measured at the resistor. These are approximate, and just to give you an idea what another Model 20 once measured. The resistor has 7 terminals with number 1 toward the front of the chassis. Voltages were measured to the chassis if I recall correctly.

terminal 1 +50 volts (varies with volume control)
terminal 2 -6.8 volts
terminal 3 chassis ground
terminal 4 +2.4 volts
terminal 5 +12 volts
terminal 6 +92 volts
terminal 7 +120 volts

Again please remember these voltages are approximate, but if you measure something very different from the above voltages, it might be an indication of possible trouble. I worked on this set in 1985, so it's been a long time but this is what I have in my notes. Another trouble spot on these early Philco sets are coils that corrode and open. That may be another thing you wish to check out. Good luck and let us know how it goes.

Gilbert
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