07-21-2013, 09:32 AM
I recently had to replace the dual control on my model 70 with a single control and am experiencing a strange problem.
Starting from fully off, the volume increases as I turn the knob clockwise but, at a fairly low level, the volume decreases and completely disappears as I continue turning the knob clockwise!
I don't have a scanner to show the circuit which came with the replacement kit which I purchased but I replaced the 225 ohm section of the original dual control with a 220 ohm fixed resistor and, to quote the instructions a 270 ohm resistor is added to "supply initial bias on RF and 1st IF grids".
This problem wasn't present before the change and wonder if anyone on the forum might have an idea as to what is causing this problem.
My apologies for such a long question for my first posting!
Thank you for your help.
Joseph
Starting from fully off, the volume increases as I turn the knob clockwise but, at a fairly low level, the volume decreases and completely disappears as I continue turning the knob clockwise!
I don't have a scanner to show the circuit which came with the replacement kit which I purchased but I replaced the 225 ohm section of the original dual control with a 220 ohm fixed resistor and, to quote the instructions a 270 ohm resistor is added to "supply initial bias on RF and 1st IF grids".
This problem wasn't present before the change and wonder if anyone on the forum might have an idea as to what is causing this problem.
My apologies for such a long question for my first posting!
Thank you for your help.
Joseph
