12-11-2024, 07:09 PM
Hi Tennangler,
Welcome to the Philco Phorum! Lots of phine phriendly phlks phull of Philco phacts. (See a pattern here?)
Was the negative lead on test point B for all the tests? If it was ion the chassis instead, you woll get verylow readings ans this is a "warm" chassis (isolated by a cap and high resistance resistor), not a "hot "chassis (one side of AC line connected directly to the chassis).
Like Gary and Morzh said, consider replacing all capacitors, especially the electrolytics, before powering up. The electrolytic and paper caps are known to short or open. There is no need to replace the mica caps in the audio section unless you find them to be bad.
Attached below is the complete schematic for Model 49-105, similar to your 49-107.
Attached below is a blow up of the power supply.
It is common for certain tubes to glow bright and dim, and the 117Z3 is no exception. However, the tube should glow an orange to almost yellow glow, and the cathode tube should glow wen te tube settles down. It is possible that the tube get intermittent, but this is not common. Most tubes either work or fail as far as the heater goes. You can CAREFULLY check for 120V AC between pins 23 and 4 when the issue occurs. If AC is there, then the tube is bad or the socket connection is bad. If not there, then investigate S100 and S101
It is important that S100 and S101be clean or you will fail the tests in the guide that you got from the Rider manual for this set. Spray switches with Caig DeOxIt contact cleaner, but use Caig DeOxIt fader lube for the volume control. Exercise the power switch (S101) by turning on and off. Exercise the AC Battery Switch (S100) by inserting the plug into the hole on the chassis designed for it. This switches the radio to battery.
Note that the filaments of the tubes other than the rectifier are all in series and run off a 7.5V battery if the unit as on battery power. Some folks would put a 9V Zener diode across the filament supply. The most convenient spot to do so is C100D
It is important to get the wiring right with this power supply, especially the cap values and the candohm, R100. Failure to do so could cause the tubes other than the rectifier to burn out. They are all pretty common except the Audio Output Tube, 3LF4. I think that these are rather rare! Note that the tubes other than the rectifier don't really light up, even in a very dark room.
Welcome to the Philco Phorum! Lots of phine phriendly phlks phull of Philco phacts. (See a pattern here?)
Was the negative lead on test point B for all the tests? If it was ion the chassis instead, you woll get verylow readings ans this is a "warm" chassis (isolated by a cap and high resistance resistor), not a "hot "chassis (one side of AC line connected directly to the chassis).
Like Gary and Morzh said, consider replacing all capacitors, especially the electrolytics, before powering up. The electrolytic and paper caps are known to short or open. There is no need to replace the mica caps in the audio section unless you find them to be bad.
Attached below is the complete schematic for Model 49-105, similar to your 49-107.
Attached below is a blow up of the power supply.
It is common for certain tubes to glow bright and dim, and the 117Z3 is no exception. However, the tube should glow an orange to almost yellow glow, and the cathode tube should glow wen te tube settles down. It is possible that the tube get intermittent, but this is not common. Most tubes either work or fail as far as the heater goes. You can CAREFULLY check for 120V AC between pins 23 and 4 when the issue occurs. If AC is there, then the tube is bad or the socket connection is bad. If not there, then investigate S100 and S101
It is important that S100 and S101be clean or you will fail the tests in the guide that you got from the Rider manual for this set. Spray switches with Caig DeOxIt contact cleaner, but use Caig DeOxIt fader lube for the volume control. Exercise the power switch (S101) by turning on and off. Exercise the AC Battery Switch (S100) by inserting the plug into the hole on the chassis designed for it. This switches the radio to battery.
Note that the filaments of the tubes other than the rectifier are all in series and run off a 7.5V battery if the unit as on battery power. Some folks would put a 9V Zener diode across the filament supply. The most convenient spot to do so is C100D
It is important to get the wiring right with this power supply, especially the cap values and the candohm, R100. Failure to do so could cause the tubes other than the rectifier to burn out. They are all pretty common except the Audio Output Tube, 3LF4. I think that these are rather rare! Note that the tubes other than the rectifier don't really light up, even in a very dark room.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis
Best Regards,
MrFixr55
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