11-30-2012, 09:59 AM
I have 4 different 42-PT95's which I am giving away as Christmas Gifts. I have made repairs on some, and others I have had others do recapping etc on them. Let us call them Radios A, B, C & D
Radio A is working fine
Radio B needs a new power on/off switch - On order
Radio C works find but low volume is too loud - new switch on order
Radio D is what my question is about.
Radio D plays well, good reception, crisp sound, able to tune stations in clear. After about 15 minutes (I set a stop watch), the tuning deteriorates, and I can no longer get crisp sound, the sound is slightly garbled.
I did what my current knowledge level allows me (I am a newbie, I can replace a capacitor or resistor, but struggle mightly at diagnosing almost any problem). I checked all the tubes. As it turned out the 7C6 tube was marginal (with readings of 50%, 62%, 65% for the 3 stages). I took another tube out of a different radio (a 7C6) and tested to see if it was better. I am going to test this at Lunch to see if this made a difference.
Here is my questions
(1) could a marginal/defective 7C6 tube cause this problem (especially when it did not occur till after 15 minutes
(2) What else might this be ? A defective resistor that is starting to fail when it gets warm ????
My quandry is that unless it is the tube, I don't have the time or expertise (right now) to solve the problem. I need to make a decision today to ship it our for repair so I may have some hope to get it back before Christmas. At another time of the year, I would just wait, but.... oh well.
In any case, if Phorum members could chime in as to what the possible causes of this might be, this will help me in my decision to ship it out or not.
Thanks
Radio A is working fine
Radio B needs a new power on/off switch - On order
Radio C works find but low volume is too loud - new switch on order
Radio D is what my question is about.
Radio D plays well, good reception, crisp sound, able to tune stations in clear. After about 15 minutes (I set a stop watch), the tuning deteriorates, and I can no longer get crisp sound, the sound is slightly garbled.
I did what my current knowledge level allows me (I am a newbie, I can replace a capacitor or resistor, but struggle mightly at diagnosing almost any problem). I checked all the tubes. As it turned out the 7C6 tube was marginal (with readings of 50%, 62%, 65% for the 3 stages). I took another tube out of a different radio (a 7C6) and tested to see if it was better. I am going to test this at Lunch to see if this made a difference.
Here is my questions
(1) could a marginal/defective 7C6 tube cause this problem (especially when it did not occur till after 15 minutes
(2) What else might this be ? A defective resistor that is starting to fail when it gets warm ????
My quandry is that unless it is the tube, I don't have the time or expertise (right now) to solve the problem. I need to make a decision today to ship it our for repair so I may have some hope to get it back before Christmas. At another time of the year, I would just wait, but.... oh well.
In any case, if Phorum members could chime in as to what the possible causes of this might be, this will help me in my decision to ship it out or not.
Thanks
