11-27-2021, 12:31 PM
Doesn't the wire from terminal 3 go to ground through cap 35 or is my schematic reading inexperience on full display here?
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An Introduction and a Philco 90 issue.
11-27-2021, 12:47 PM
Here is the schematic I am looking at Early Schematics – Philco Library (philcoradio.com) (scroll down to 90 mid version) In this schematic there is a cap number 38 but, unless the cap is shorted, it won't change the reading.
M R Radios C M Tubes 
11-27-2021, 02:39 PM
OK I was doing something stupid. The wire from terminal 3 is fine...it reads infinite resistance to ground. The wire from BC resistor terminal 4 is the same readings as before...90.4k ohms with the speaker unplugged...3200 ohms with the speaker plugged in.
Pics show these 2 readings, the speaker socket and the general area around the speaker socket. All tubes are out. In the last pic, that small black box attachment is for a 1/4" jack input for Bluetooth and similar input. Pretty sure it's not an issue. Radio and it worked fine before.
11-27-2021, 04:08 PM
Chris, when you recapped the chassis, did you replace the caps in the tone control?
M R Radios C M Tubes
11-27-2021, 04:39 PM
No I did not...I just sprayed contact cleaner on the 3 tabs and worked the controls
11-27-2021, 04:51 PM
OK, with the speaker plugged in, repeat the resistance check on wire 4. This time, turn the tone control to each position while checking.
M R Radios C M Tubes
11-27-2021, 07:13 PM
Steve...it is 3200 ohms in all 3 positions on the tone control
11-27-2021, 08:04 PM
The tone control should have four positions. When the control is fully counter clock-wise you still get 32K?
M R Radios C M Tubes
11-27-2021, 09:27 PM
Yes, I meant 3.2K. Take resistance measurements on all speaker plug terminals first with the speaker plugged in and again with the speaker unplugged.
Steve M R Radios C M Tubes
11-27-2021, 11:09 PM
OK starting on speaker socket that is connected to BC terminal 4 and going clockwise.
Speaker plugged in: 1. 3200 ohms 2. Infinity 3. 98k ohms 4. 20 ohms Speaker unplugged: 1. 90.6k ohms 2. Infinity 3. Infinity 4. 22 ohms
11-28-2021, 01:34 PM
The B+ line (speaker socket terminal 4) is shorted. You will need to trace that line all the way through.
Steve M R Radios C M Tubes
11-28-2021, 01:55 PM
Will do...thanks so much Steve...I'll get back to you. It's socket 4, the one that's reading 20 ohms plugged or unplugged correct?
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