Have an old sparton may be a 7-46, not sure off hand. Had 5U4 power and 2 6V6 amplifiers. It blew after a while. Replaced the 5U4 with 5Y3 which is specs. Replaced the 6V6's with 6F6 metal can type. Calls for 6F6GT...not working at all. No shorts...nothing. Could 6F6's be the problem? Bought them online, tested strong. Know that doesn't hold much water. Any ideas. 5Y3 is good and tried changing it out too. Nothing again. Hate to take that beast apart again to measure everything...so hard to line up. Looking for a quick fix. Used to work fine...don't get it. Thanks.

:Have an old sparton may be a 7-46, not sure off hand. Had 5U4 power and 2 6V6 amplifiers. It blew after a while. Replaced the 5U4 with 5Y3 which is specs. Replaced the 6V6's with 6F6 metal can type. Calls for 6F6GT...not working at all. No shorts...nothing. Could 6F6's be the problem? Bought them online, tested strong. Know that doesn't hold much water. Any ideas. 5Y3 is good and tried changing it out too. Nothing again. Hate to take that beast apart again to measure everything...so hard to line up. Looking for a quick fix. Used to work fine...don't get it. Thanks.
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More info is needed. What blew? The rectifier 5U4? It may have taken out another component. Is it possible the 5 volt transformer winding is burned out, rather than the tube?

You said " it blew after a while " What did ? The radio being dead would indicate power supply. You can unplug the speaker to check the field coil and audio output transformer plus the speaker. Other than that you will need to remove the chassis and check the B+.

:Have an old sparton may be a 7-46, not sure off hand. Had 5U4 power and 2 6V6 amplifiers. It blew after a while. Replaced the 5U4 with 5Y3 which is specs. Replaced the 6V6's with 6F6 metal can type. Calls for 6F6GT...not working at all. No shorts...nothing. Could 6F6's be the problem? Bought them online, tested strong. Know that doesn't hold much water. Any ideas. 5Y3 is good and tried changing it out too. Nothing again. Hate to take that beast apart again to measure everything...so hard to line up. Looking for a quick fix. Used to work fine...don't get it. Thanks.
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Hi Jerry,
I think think the others will agree with me that it isn't the tubes. When tubes go, they tend not to go in groups unless something wrecks them.
I know you don't want to dismatle the radio, but it looks like that is where you are. The recommendations of the other two are a good start, especially checking the B+ from the speaker connection. That can be done without removing the chassis.

All the Best,

Bill Grimm

::Have an old sparton may be a 7-46, not sure off hand. Had 5U4 power and 2 6V6 amplifiers. It blew after a while. Replaced the 5U4 with 5Y3 which is specs. Replaced the 6V6's with 6F6 metal can type. Calls for 6F6GT...not working at all. No shorts...nothing. Could 6F6's be the problem? Bought them online, tested strong. Know that doesn't hold much water. Any ideas. 5Y3 is good and tried changing it out too. Nothing again. Hate to take that beast apart again to measure everything...so hard to line up. Looking for a quick fix. Used to work fine...don't get it. Thanks.
::
:Hi Jerry,
: I think think the others will agree with me that it isn't the tubes. When tubes go, they tend not to go in groups unless something wrecks them.
: I know you don't want to dismatle the radio, but it looks like that is where you are. The recommendations of the other two are a good start, especially checking the B+ from the speaker connection. That can be done without removing the chassis.
:
:All the Best,
:
:Bill Grimm
:
Also, if I may add, you can remove tubes and measure voltages at the tube sockets. Use a high setting on your meter and be prepared for voltages over 350 vac.