I just replaced all the paper and electrolytic capacitors in this radio, and I'm listening to it. I hear a high frequency ear piercing noise in the sound. I can vary it by adjusting the tone control.
One of the output tubes is missing. There is another problem: I can only hear sound if that tube is in one of the output sockets but no sound is heard if it's placed in the other socket. So an open output transformer is a possibility.
But, the high frequency noise may be another problem or I made a mistake somewhere. Where should I check for a mistake that would introduce this noise or could this problem be due to the missing output tube? I never had a problem with a missing output tube in a push-pull circuit if I'm just testing an amplifier, even if there is some sound missing, it never whistles like this.
Thanks,
Dave
If that happens to be for a circa 62-62 Chrysler vintage product and it using in the order of a pair of 6AQ5’s / 6V6’s and a 6C4,
I would tend to suspicion that quirk being due to the phase inverter stage not having a balanced load presented to its output, and the resultant manner in which one output tube position responds.
As far as one position of the output tube not having sound. . .. check the circuitry of the phase inverter to see its plate output
connection and its associated coupling capacitor going over to its output tube being fed and confirm if that isn’t the one that has sound output when having an output tube plugged into that position.
Then. . . check the other output tubes plate to see if it has plate voltage on it, thus, confirming some degree of output transformer integrity, Then move the output tube to the position where there was no sound and take a jumper lead and connect between the vacant tubes 1st grid and the 1st grid of the now silent condition on the just installed output tube and see if the sound then comes up from a known confirmed source of drive (albeit phase shifted). Otherwise, that drive was supposed to be coming forth from the cathode circuitry of the phase inverter.
Feedback time. . ..
73's de Edd
This radio is from 1956. I'll follow your suggestions later this evening.
Thanks very much,
Dave
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:If that happens to be for a circa 62-62 Chrysler vintage product and it using in the order of a pair of 6AQ5’s / 6V6’s and a 6C4,
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:I would tend to suspicion that quirk being due to the phase inverter stage not having a balanced load presented to its output, and the resultant manner in which one output tube position responds.
:
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:As far as one position of the output tube not having sound. . .. check the circuitry of the phase inverter to see its plate output
: connection and its associated coupling capacitor going over to its output tube being fed and confirm if that isn’t the one that has sound output when having an output tube plugged into that position.
:
:
:Then. . . check the other output tubes plate to see if it has plate voltage on it, thus, confirming some degree of output transformer integrity, Then move the output tube to the position where there was no sound and take a jumper lead and connect between the vacant tubes 1st grid and the 1st grid of the now silent condition on the just installed output tube and see if the sound then comes up from a known confirmed source of drive (albeit phase shifted). Otherwise, that drive was supposed to be coming forth from the cathode circuitry of the phase inverter.
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:Feedback time. . ..
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:73's de Edd
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I found my mistake. I forgot to snip the excess wire from a capacitor after soldering. I have no idea how I could have done such a thing. But it happens sometimes. All is well with the 842HR.
Thanks,
Dave
:Edd,
: This radio is from 1956. I'll follow your suggestions later this evening.
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:Thanks very much,
:
:Dave
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::If that happens to be for a circa 62-62 Chrysler vintage product and it using in the order of a pair of 6AQ5’s / 6V6’s and a 6C4,
::
::I would tend to suspicion that quirk being due to the phase inverter stage not having a balanced load presented to its output, and the resultant manner in which one output tube position responds.
::
::
::As far as one position of the output tube not having sound. . .. check the circuitry of the phase inverter to see its plate output
:: connection and its associated coupling capacitor going over to its output tube being fed and confirm if that isn’t the one that has sound output when having an output tube plugged into that position.
::
::
::Then. . . check the other output tubes plate to see if it has plate voltage on it, thus, confirming some degree of output transformer integrity, Then move the output tube to the position where there was no sound and take a jumper lead and connect between the vacant tubes 1st grid and the 1st grid of the now silent condition on the just installed output tube and see if the sound then comes up from a known confirmed source of drive (albeit phase shifted). Otherwise, that drive was supposed to be coming forth from the cathode circuitry of the phase inverter.
::
::
::
::Feedback time. . ..
::
::
::
::73's de Edd
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