Your radio must be AC/DC with filaments wired in series. The lamp will be across a section of the rectifier tube, usually 35Z5GT or 35W4. If this section of filament is open the lamp will burn out on turn due to a surge.
With an ohm meter check between pins #2 & #7 on a 35Z5GT and 3 & 4 on a 35W4. The radio will still work even though a section is open due to the filament tap.
Norm
: This should be a non-problem, but its got me stumped. I have cleaned up and recapped a simple 1950 RCA, model #9-X-641. When I replaced the dial lamp and turned on the set, it promptly blew out. The set does not function unless the dial lamp is in and working. When I bring up the voltage slowly with my variac, the lamp glows brightly, then dims, then glows brightly again, as expected. However, if I take the power cord and plug it directly into an outlet and turn on the power, the dial lamp blows right out. I measured the voltage across the dial lamp socket and it read 14V. I tried using a 14V, 250 mA lamp. No dice, same thing. The set works fine otherwise with good sound. Any suggestions? Thanks!
: Your radio must be AC/DC with filaments wired in series. The lamp will be across a section of the rectifier tube, usually 35Z5GT or 35W4. If this section of filament is open the lamp will burn out on turn due to a surge.
: With an ohm meter check between pins #2 & #7 on a 35Z5GT and 3 & 4 on a 35W4. The radio will still work even though a section is open due to the filament tap.
: Norm
:
: : This should be a non-problem, but its got me stumped. I have cleaned up and recapped a simple 1950 RCA, model #9-X-641. When I replaced the dial lamp and turned on the set, it promptly blew out. The set does not function unless the dial lamp is in and working. When I bring up the voltage slowly with my variac, the lamp glows brightly, then dims, then glows brightly again, as expected. However, if I take the power cord and plug it directly into an outlet and turn on the power, the dial lamp blows right out. I measured the voltage across the dial lamp socket and it read 14V. I tried using a 14V, 250 mA lamp. No dice, same thing. The set works fine otherwise with good sound. Any suggestions? Thanks!
Resistance will be very low for a good tube, less than 100 ohms. A bad tube will be open
If this is the problem replacing the tube will fix the radio but be sure electrolytic filter caps have been replaced. They caps can draw excessive current which initally could have caused the tube to blow.
Norm
: Norm: The radio uses a 35Z5GT as the rectifier. What should the resistance be between pins #2 and #7? I will check them tomorrow to see what they are. Can the solution be something as simple as changing to a known good 35Z5GT tube? Thanks!
: : Hi Jeff
: : Your radio must be AC/DC with filaments wired in series. The lamp will be across a section of the rectifier tube, usually 35Z5GT or 35W4. If this section of filament is open the lamp will burn out on turn due to a surge.
: : With an ohm meter check between pins #2 & #7 on a 35Z5GT and 3 & 4 on a 35W4. The radio will still work even though a section is open due to the filament tap.
: : Norm
: :
: : : This should be a non-problem, but its got me stumped. I have cleaned up and recapped a simple 1950 RCA, model #9-X-641. When I replaced the dial lamp and turned on the set, it promptly blew out. The set does not function unless the dial lamp is in and working. When I bring up the voltage slowly with my variac, the lamp glows brightly, then dims, then glows brightly again, as expected. However, if I take the power cord and plug it directly into an outlet and turn on the power, the dial lamp blows right out. I measured the voltage across the dial lamp socket and it read 14V. I tried using a 14V, 250 mA lamp. No dice, same thing. The set works fine otherwise with good sound. Any suggestions? Thanks!