I purchased this in really bad shape. I have fixed the cracks repainted and recapped the unit. My problem is that after 10-15 minutes of play the output becomes distorted. It is almost like when tuning a station you just are not quite on it, but when first turned on it plays great. I looked for the schm. but could not find it. Can it be that when I test the tubes I will need to leave them in for approx 10 min if a tube is the problem. Please help. thank you, Peter

Hi Peter

Measure your output tube grid #1 voltage in relation to cathode. It must be several volts negative. If positive there will be distortion and excessive current drawn.

The problem will usually be a leaky coupling cap to grid #1. An open grid resistor or bad output tube can also cause the problem. It gets worse as tubes heat.

Norm

:I purchased this in really bad shape. I have fixed the cracks repainted and recapped the unit. My problem is that after 10-15 minutes of play the output becomes distorted. It is almost like when tuning a station you just are not quite on it, but when first turned on it plays great. I looked for the schm. but could not find it. Can it be that when I test the tubes I will need to leave them in for approx 10 min if a tube is the problem. Please help. thank you, Peter

:Hi Peter
:
: Measure your output tube grid #1 voltage in relation to cathode. It must be several volts negative. If positive there will be distortion and excessive current drawn.
:
: The problem will usually be a leaky coupling cap to grid #1. An open grid resistor or bad output tube can also cause the problem. It gets worse as tubes heat.
:
:Norm
:
::I purchased this in really bad shape. I have fixed the cracks repainted and recapped the unit. My problem is that after 10-15 minutes of play the output becomes distorted. It is almost like when tuning a station you just are not quite on it, but when first turned on it plays great. I looked for the schm. but could not find it. Can it be that when I test the tubes I will need to leave them in for approx 10 min if a tube is the problem. Please help. thank you, Peter

:Hi Norm,
:
: First thank you for your quick response. I changed out the tube with a known good one not the problem. I have already replaced the cap when I recapped the unit, and the resistors are all with in spec. So what was the problem, well, I was even surprised. It was the speaker it had a fine crack in it all the way down to the coil, plus the coil needeed some glue. Now the radio plays crystal clear and sounds great. I want to thank you for your help which let me deduct the possibly causes. You have helped me before and as always it it very appreciated.
:
: Thank you, Peter

:Hi Peter
:
: Measure your output tube grid #1 voltage in relation to cathode. It must be several volts negative. If positive there will be distortion and excessive current drawn.
:
: The problem will usually be a leaky coupling cap to grid #1. An open grid resistor or bad output tube can also cause the problem. It gets worse as tubes heat.
:
:Norm
:
::I purchased this in really bad shape. I have fixed the cracks repainted and recapped the unit. My problem is that after 10-15 minutes of play the output becomes distorted. It is almost like when tuning a station you just are not quite on it, but when first turned on it plays great. I looked for the schm. but could not find it. Can it be that when I test the tubes I will need to leave them in for approx 10 min if a tube is the problem. Please help. thank you, Peter