dial bulb

4/27/2002 8:40:05 AMMike

My 1946 Crosley, a huge project, finally plays well and sounds good. I still have on problem that I can't figure out. When you first turn the radio on, the dial bulb glows orange and gradually brightens until after about 10 minutes it flashes and burns out. The last time this happened, I also lost a 150 ohm, 1/2 watt resistor that goes from pin 2 to pin 3 of the 35Z5GT rectifier. The resistor and a .05 capacitor seem to be a part of the dial bulb circuit, though I'm not expert enough to know for sure. Pin 2 of the 35Z5 is a heater and pin 3 is marked as HL. I'm not sure what that means, either. The radio continues to work fine after the bulb flashes out. Any ideas about what's failing? Thanks.

4/27/2002 12:09:25 PMNorm Leal

Hi Mike

The lamp is wired across a section of 35Z5 filament. This in turn supplies voltage to the plate. As a radio draws B+ current the lamp will become brighter. If it actually burns out something is drawing excessive current or the section of filament between pin #2 and #3 is open.

Were the electrolytic filter caps replaced? Is pin #5 of 50L6 5 volts negative when measured from pin #8? These items can cause excessive current to be drawn.

Measure continuity of 35Z5 filament. Pins #2, #3 and #7 should all show continuity. If not your tube is bad.

Norm

: My 1946 Crosley, a huge project, finally plays well and sounds good. I still have on problem that I can't figure out. When you first turn the radio on, the dial bulb glows orange and gradually brightens until after about 10 minutes it flashes and burns out. The last time this happened, I also lost a 150 ohm, 1/2 watt resistor that goes from pin 2 to pin 3 of the 35Z5GT rectifier. The resistor and a .05 capacitor seem to be a part of the dial bulb circuit, though I'm not expert enough to know for sure. Pin 2 of the 35Z5 is a heater and pin 3 is marked as HL. I'm not sure what that means, either. The radio continues to work fine after the bulb flashes out. Any ideas about what's failing? Thanks.

4/27/2002 12:23:00 PMmike

: Hi Mike

: The lamp is wired across a section of 35Z5 filament. This in turn supplies voltage to the plate. As a radio draws B+ current the lamp will become brighter. If it actually burns out something is drawing excessive current or the section of filament between pin #2 and #3 is open.

: Were the electrolytic filter caps replaced? Is pin #5 of 50L6 5 volts negative when measured from pin #8? These items can cause excessive current to be drawn.

: Measure continuity of 35Z5 filament. Pins #2, #3 and #7 should all show continuity. If not your tube is bad.

: Norm
:

: : My 1946 Crosley, a huge project, finally plays well and sounds good. I still have on problem that I can't figure out. When you first turn the radio on, the dial bulb glows orange and gradually brightens until after about 10 minutes it flashes and burns out. The last time this happened, I also lost a 150 ohm, 1/2 watt resistor that goes from pin 2 to pin 3 of the 35Z5GT rectifier. The resistor and a .05 capacitor seem to be a part of the dial bulb circuit, though I'm not expert enough to know for sure. Pin 2 of the 35Z5 is a heater and pin 3 is marked as HL. I'm not sure what that means, either. The radio continues to work fine after the bulb flashes out. Any ideas about what's failing? Thanks.

4/29/2002 9:54:50 AMmike

Norm: I did have a bad tube. Thanks for your help. The old Crosley is finally finished.

Hi Mike: The lamp is wired across a section of 35Z5 filament. This in turn supplies voltage to the plate. As a radio draws B+ current the lamp will become brighter. If it actually burns out something is drawing excessive current or the section of filament between pin #2 and #3 is open.

: : Were the electrolytic filter caps replaced? Is pin #5 of 50L6 5 volts negative when measured from pin #8? These items can cause excessive current to be drawn.

: : Measure continuity of 35Z5 filament. Pins #2, #3 and #7 should all show continuity. If not your tube is bad.

: : Norm
: :

: : : My 1946 Crosley, a huge project, finally plays well and sounds good. I still have on problem that I can't figure out. When you first turn the radio on, the dial bulb glows orange and gradually brightens until after about 10 minutes it flashes and burns out. The last time this happened, I also lost a 150 ohm, 1/2 watt resistor that goes from pin 2 to pin 3 of the 35Z5GT rectifier. The resistor and a .05 capacitor seem to be a part of the dial bulb circuit, though I'm not expert enough to know for sure. Pin 2 of the 35Z5 is a heater and pin 3 is marked as HL. I'm not sure what that means, either. The radio continues to work fine after the bulb flashes out. Any ideas about what's failing? Thanks.

4/27/2002 12:23:49 PMmike

: Hi Mike

: The lamp is wired across a section of 35Z5 filament. This in turn supplies voltage to the plate. As a radio draws B+ current the lamp will become brighter. If it actually burns out something is drawing excessive current or the section of filament between pin #2 and #3 is open.

: Were the electrolytic filter caps replaced? Is pin #5 of 50L6 5 volts negative when measured from pin #8? These items can cause excessive current to be drawn.

: Measure continuity of 35Z5 filament. Pins #2, #3 and #7 should all show continuity. If not your tube is bad.

: Norm
:

: : My 1946 Crosley, a huge project, finally plays well and sounds good. I still have on problem that I can't figure out. When you first turn the radio on, the dial bulb glows orange and gradually brightens until after about 10 minutes it flashes and burns out. The last time this happened, I also lost a 150 ohm, 1/2 watt resistor that goes from pin 2 to pin 3 of the 35Z5GT rectifier. The resistor and a .05 capacitor seem to be a part of the dial bulb circuit, though I'm not expert enough to know for sure. Pin 2 of the 35Z5 is a heater and pin 3 is marked as HL. I'm not sure what that means, either. The radio continues to work fine after the bulb flashes out. Any ideas about what's failing? Thanks.

4/27/2002 12:26:00 PMmike

Hi Norm:
I have replaced the elctrolytics and the 50L6 voltage is good. I did have some trouble with the output stage at one time but got it fixed. I'll check the tube filaments. Thanks for your help.

Hi Mike

: The lamp is wired across a section of 35Z5 filament. This in turn supplies voltage to the plate. As a radio draws B+ current the lamp will become brighter. If it actually burns out something is drawing excessive current or the section of filament between pin #2 and #3 is open.

: Were the electrolytic filter caps replaced? Is pin #5 of 50L6 5 volts negative when measured from pin #8? These items can cause excessive current to be drawn.

: Measure continuity of 35Z5 filament. Pins #2, #3 and #7 should all show continuity. If not your tube is bad.

: Norm
:

: : My 1946 Crosley, a huge project, finally plays well and sounds good. I still have on problem that I can't figure out. When you first turn the radio on, the dial bulb glows orange and gradually brightens until after about 10 minutes it flashes and burns out. The last time this happened, I also lost a 150 ohm, 1/2 watt resistor that goes from pin 2 to pin 3 of the 35Z5GT rectifier. The resistor and a .05 capacitor seem to be a part of the dial bulb circuit, though I'm not expert enough to know for sure. Pin 2 of the 35Z5 is a heater and pin 3 is marked as HL. I'm not sure what that means, either. The radio continues to work fine after the bulb flashes out. Any ideas about what's failing? Thanks.