After recapping, it intially had low volume, then worked fine on its own for several days. Soon I noticed that after turning it on, I would hear a clicking/tapping noise as it warmed up (like you hear when a light bulb goes out). It still worked fine after warming up.
The next day, no more tapping sound and no volume after starting up. The only cap change I made that was different from what was in the radio initially was I put two series .001 caps at 630v each in place of one .0005 1000v cap across the speaker socket (C14 in the schematic) because I did not have the .0005.
The rectifier (5Y3) and the pentode power amp (6F6) always ran very hot- too hot to touch. Now the 6F6 doesnt get hot at all, only warm to the touch. The tapping sound seemed to come from the tube (6F6) side of the radio also. I do not have a tube tester and the .0005m cap was also in that same 6F6 circuit.
The tube was dinged up when I got the radio, leading me to believe it was mishandled anyway. The base is a little loose also.
Before I put the new 6F6 in, does anyone concur with my thought that the tube is bad? Should I try something else before I use a new tube, when I get it(I am afraid I might burn it out). I did order a .0005 1000v cap as the schematic calls for that I intend to replace instead of the two series .001m caps I substituted initially, but I dont think that would cause this problem.
Any help would be appreciated.
Thanks,
Steve
Check the 6F6 tube socket ground to chassis. Sometimes the rivets that hold the socket become high resistance.
Anything connected to the ground lugs on that socket are not getting a good ground. Also check the B+ at the plate of the 6F6. If that voltage is low or none, follow it back to the 5Y3. That tube could be weak or have a ground fault around there too.
If you hear anything out of the radio your 6F6 isn't damaged. I've seen metal 6F6 tubes dented and still operate. Tube base being loose isn't a problem unless wires have pulled out.
Tapping may be caused by bad filter caps. Sound may be a form of low frequency motorboating? If so it will go away when electrolytic filter caps are replaced.
Norm
::I recently picked up this radio. I was not used for many years judging from the condition. After a good cleaning and careful start up, it worked fine. I then decided to recapp just to improve reliability as I am using it every day.
::
::After recapping, it intially had low volume, then worked fine on its own for several days. Soon I noticed that after turning it on, I would hear a clicking/tapping noise as it warmed up (like you hear when a light bulb goes out). It still worked fine after warming up.
::
::The next day, no more tapping sound and no volume after starting up. The only cap change I made that was different from what was in the radio initially was I put two series .001 caps at 630v each in place of one .0005 1000v cap across the speaker socket (C14 in the schematic) because I did not have the .0005.
::
::The rectifier (5Y3) and the pentode power amp (6F6) always ran very hot- too hot to touch. Now the 6F6 doesnt get hot at all, only warm to the touch. The tapping sound seemed to come from the tube (6F6) side of the radio also. I do not have a tube tester and the .0005m cap was also in that same 6F6 circuit.
::
::The tube was dinged up when I got the radio, leading me to believe it was mishandled anyway. The base is a little loose also.
::
::Before I put the new 6F6 in, does anyone concur with my thought that the tube is bad? Should I try something else before I use a new tube, when I get it(I am afraid I might burn it out). I did order a .0005 1000v cap as the schematic calls for that I intend to replace instead of the two series .001m caps I substituted initially, but I dont think that would cause this problem.
::
::Any help would be appreciated.
::
::Thanks,
::Steve
:
:Check the 6F6 tube socket ground to chassis. Sometimes the rivets that hold the socket become high resistance.
:Anything connected to the ground lugs on that socket are not getting a good ground. Also check the B+ at the plate of the 6F6. If that voltage is low or none, follow it back to the 5Y3. That tube could be weak or have a ground fault around there too.
:Hi Steve
:
: If you hear anything out of the radio your 6F6 isn't damaged. I've seen metal 6F6 tubes dented and still operate. Tube base being loose isn't a problem unless wires have pulled out.
:
: Tapping may be caused by bad filter caps. Sound may be a form of low frequency motorboating? If so it will go away when electrolytic filter caps are replaced.
:
:Norm
:
:::I recently picked up this radio. I was not used for many years judging from the condition. After a good cleaning and careful start up, it worked fine. I then decided to recapp just to improve reliability as I am using it every day.
:::
:::After recapping, it intially had low volume, then worked fine on its own for several days. Soon I noticed that after turning it on, I would hear a clicking/tapping noise as it warmed up (like you hear when a light bulb goes out). It still worked fine after warming up.
:::
:::The next day, no more tapping sound and no volume after starting up. The only cap change I made that was different from what was in the radio initially was I put two series .001 caps at 630v each in place of one .0005 1000v cap across the speaker socket (C14 in the schematic) because I did not have the .0005.
:::
:::The rectifier (5Y3) and the pentode power amp (6F6) always ran very hot- too hot to touch. Now the 6F6 doesnt get hot at all, only warm to the touch. The tapping sound seemed to come from the tube (6F6) side of the radio also. I do not have a tube tester and the .0005m cap was also in that same 6F6 circuit.
:::
:::The tube was dinged up when I got the radio, leading me to believe it was mishandled anyway. The base is a little loose also.
:::
:::Before I put the new 6F6 in, does anyone concur with my thought that the tube is bad? Should I try something else before I use a new tube, when I get it(I am afraid I might burn it out). I did order a .0005 1000v cap as the schematic calls for that I intend to replace instead of the two series .001m caps I substituted initially, but I dont think that would cause this problem.
:::
:::Any help would be appreciated.
:::
:::Thanks,
:::Steve
::
::Check the 6F6 tube socket ground to chassis. Sometimes the rivets that hold the socket become high resistance.
::Anything connected to the ground lugs on that socket are not getting a good ground. Also check the B+ at the plate of the 6F6. If that voltage is low or none, follow it back to the 5Y3. That tube could be weak or have a ground fault around there too.
The tapping/clicking only occurred a couple of times, when the radio was cold and not through the speaker. After a few seconds the tapping went away and the radio worked fine.
The next day there was no tapping when cold and no sound at all as I tried to turn it on and after enough time to warm up. F6F is noticeably cool to touch (about 125F) and the electrolytics have been replaced (a week ago). I dont get over a few volts (AC) on the F6F plate. There is high voltage (about 221V)to the speaker coil. The 5Y3 runs hot (275F) and voltage is about 221 v. The radio worked fine until I changed all the other caps a week later.
Ground checks ok on the 6F6 also. Still no sound. I suspect the F6F because I read that they run hot (only about 50% efficient) and this one does not anymore.
Question: When I check voltages with an RMS meter, the voltages go form zero and up to the final volts that I stated I measured above, then back to zero and up again over and over. Is this normal (I am new to radio restoration)? I suspect this is so as AC is a sine wave amd voltage varies.
Thanks
The use of an RMS meter is for basic AC. What you should be using is a volt ohm meter. You will need to be reading DC voltage in radios. The plate of the 6F6 is all DC. The only AC will be before the rectifier, and the tube heaters.