I'm working on a Brunswick Canada Model D chassis. I've done some work on it and it is playing not too bad. I've come across a problem with the volume. After the radio plays for several minutes and I am tuning in stations the volume will suddenly go to maximum loudness. I cannot turn it down by adjusting the knob so I must turn it off for a period of time. When I turn it back on, it works fine for a while then repeats the same proceedure. any help/ideas where I should begin my search to eliminate this would be most appreciated.
Cheers, John

Seems like the volume control is opening up (on the low side) or the connection is intermittent. Try heating up the solder on the control and ground connection and see if that solves the problem. Don't have the schematic handy, but if the low side does not connect directly to ground, but through a resistor, then it may be also be bad, so just replace it.

:I'm working on a Brunswick Canada Model D chassis. I've done some work on it and it is playing not too bad. I've come across a problem with the volume. After the radio plays for several minutes and I am tuning in stations the volume will suddenly go to maximum loudness. I cannot turn it down by adjusting the knob so I must turn it off for a period of time. When I turn it back on, it works fine for a while then repeats the same proceedure. any help/ideas where I should begin my search to eliminate this would be most appreciated.
:Cheers, John
:

Hi

This should be the schematic:

http://www.nostalgiaair.org/PagesByModel/838/M0028838.pdf

There is an error in volume control area on the schematic. The 300 ohm resistor shouldn't have a dot where it croses the line.

The .1 mf cap from tube cathodes to ground may be shorting? Usually 1 filament pin is grounded. If so filament may be shorting to cathode inside a tube?

Norm

:Seems like the volume control is opening up (on the low side) or the connection is intermittent. Try heating up the solder on the control and ground connection and see if that solves the problem. Don't have the schematic handy, but if the low side does not connect directly to ground, but through a resistor, then it may be also be bad, so just replace it.
:
::I'm working on a Brunswick Canada Model D chassis. I've done some work on it and it is playing not too bad. I've come across a problem with the volume. After the radio plays for several minutes and I am tuning in stations the volume will suddenly go to maximum loudness. I cannot turn it down by adjusting the knob so I must turn it off for a period of time. When I turn it back on, it works fine for a while then repeats the same proceedure. any help/ideas where I should begin my search to eliminate this would be most appreciated.
::Cheers, John
::
:
:

:Hi
:
: This should be the schematic:
:
:http://www.nostalgiaair.org/PagesByModel/838/M0028838.pdf
:
: There is an error in volume control area on the schematic. The 300 ohm resistor shouldn't have a dot where it croses the line.
:
: The .1 mf cap from tube cathodes to ground may be shorting? Usually 1 filament pin is grounded. If so filament may be shorting to cathode inside a tube?
:
:Norm
:
::Seems like the volume control is opening up (on the low side) or the connection is intermittent. Try heating up the solder on the control and ground connection and see if that solves the problem. Don't have the schematic handy, but if the low side does not connect directly to ground, but through a resistor, then it may be also be bad, so just replace it.
::
:::I'm working on a Brunswick Canada Model D chassis. I've done some work on it and it is playing not too bad. I've come across a problem with the volume. After the radio plays for several minutes and I am tuning in stations the volume will suddenly go to maximum loudness. I cannot turn it down by adjusting the knob so I must turn it off for a period of time. When I turn it back on, it works fine for a while then repeats the same proceedure. any help/ideas where I should begin my search to eliminate this would be most appreciated.
:::Cheers, John
:::
::
::
:
:

::Thanks guys, I've got a copy of the schematic and after enlarging it I see what you are talking about here Norm. In the tube compliment the 235's have been replaced with 35E's which should be alright I think. What is scary about this set is a note on the back indicating not to replace the 80 with a good tube as the circuit has been changed. How I'm not sure and I'm not going there as it is now working, with the exception of my little volume flare problem and the sound is a bit fuzzy. I have not replace all of the caps yet. I'll follow up once I get more done.

Hi
::
:: This should be the schematic:
::
::http://www.nostalgiaair.org/PagesByModel/838/M0028838.pdf
::
:: There is an error in volume control area on the schematic. The 300 ohm resistor shouldn't have a dot where it croses the line.
::
:: The .1 mf cap from tube cathodes to ground may be shorting? Usually 1 filament pin is grounded. If so filament may be shorting to cathode inside a tube?
::
::Norm
::
:::Seems like the volume control is opening up (on the low side) or the connection is intermittent. Try heating up the solder on the control and ground connection and see if that solves the problem. Don't have the schematic handy, but if the low side does not connect directly to ground, but through a resistor, then it may be also be bad, so just replace it.
:::
::::I'm working on a Brunswick Canada Model D chassis. I've done some work on it and it is playing not too bad. I've come across a problem with the volume. After the radio plays for several minutes and I am tuning in stations the volume will suddenly go to maximum loudness. I cannot turn it down by adjusting the knob so I must turn it off for a period of time. When I turn it back on, it works fine for a while then repeats the same proceedure. any help/ideas where I should begin my search to eliminate this would be most appreciated.
::::Cheers, John
::::
:::
:::
::
::
:
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