Philco 37-610 Thump*No 7 Volts to pilot lamp - Printable Version
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RE: Philco 37-610 Thump*No 7 Volts to pilot lamp - MrFixr55 - 04-06-2024
Hi Ralph,
Other experts please chime in if I am wrong here. Most restorers will accept up to a 20% error in the resistor value for older radios because most of the resistors have a tolerance of 20%. Replacing the 2 resistors with the lower values that you described would still put you in about a 10% error. since they are oth 10% lower, in theory, the voltage would be no different than the theoretical design voltage.
Much has been said by others responding to your post, all very good info. do consider reheating solder connections, ohming coils, and verifying circuit continuity through the band switch. Definitely verify grounds. Consider bonding ground points to each other if the chassis is rusty.
If you have a signal generator, it would be a useful tool in troubleshooting this issue.
RE: Philco 37-610 Thump*No 7 Volts to pilot lamp - Joe Rossi - 04-06-2024
I agree with MrFixr regarding resistor replacement tolerances.
RE: Philco 37-610 Thump*No 7 Volts to pilot lamp - morzh - 04-06-2024
20% seems to be the commonly accepted tolerance. Keeep in mind, this is +/-20% which makes it 40% (counting from the center value) range.
It's possible there are some places where one might want a tighter tolerance, but most will be OK with 20%.
RE: Philco 37-610 Thump*No 7 Volts to pilot lamp - RodB - 04-07-2024
Keep in mind we don't really know what values the engineers came up with. All we see is what is on the drawing and what is inside the chassis. They used the closest component value to what the calculated one was, plus the parts manufacturers couldn't get much closer than 20% for standard parts. It's evident that cost often determined the final parts placement (what do you mean I can't add fidelity?). So this is why I use 10 percent tolerance. Plus, it's easy to calculate.
RE: Philco 37-610 Thump*No 7 Volts to pilot lamp - Ralph - 04-07-2024
Mr Fixr,
I have replaced resistors #22,23 and 47 All voltages are with in 20% except 6K7 plate voltage is 63v not 175v
With power off 0 ohms between pin 5 and ground.
No stations when touching grid cap of 6A8. When testing with another radio I did not get any squealing. When moving the radio outside I did get 3 stations fainty with a .1 cap on screw #1 of the antenna with screws 2 and 3 jumped and me touching the cap. No stations when using wire for a antenna.
2 things did happen while trying to get it to play. playing with grid cap of 6K7 I got some motor boating also when wiggling the center chassis I could get the motor boating to come and go. Do I need to replace the grommet's on the center chassis?
The antenna lead going to the band switch needs to be resoldered, the radio shows its not a good connection when wiggling the wire. Looks very hard to get at the soldering point of the band switch.
Ralph