An Introduction and a Philco 90 issue. - Printable Version
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+--- Thread: An Introduction and a Philco 90 issue. (/showthread.php?tid=23024)
RE: An Introduction and a Philco 90 issue. - cknob - 11-27-2021
Doesn't the wire from terminal 3 go to ground through cap 35 or is my schematic reading inexperience on full display here?
RE: An Introduction and a Philco 90 issue. - Steve Davis - 11-27-2021
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.
RE: An Introduction and a Philco 90 issue. - cknob - 11-27-2021
OK that's the schematic I have.
RE: An Introduction and a Philco 90 issue. - cknob - 11-27-2021
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.
RE: An Introduction and a Philco 90 issue. - Steve Davis - 11-27-2021
Chris, when you recapped the chassis, did you replace the caps in the tone control?
RE: An Introduction and a Philco 90 issue. - cknob - 11-27-2021
No I did not...I just sprayed contact cleaner on the 3 tabs and worked the controls
RE: An Introduction and a Philco 90 issue. - Steve Davis - 11-27-2021
OK, with the speaker plugged in, repeat the resistance check on wire 4. This time, turn the tone control to each position while checking.
RE: An Introduction and a Philco 90 issue. - cknob - 11-27-2021
Steve...it is 3200 ohms in all 3 positions on the tone control
RE: An Introduction and a Philco 90 issue. - Steve Davis - 11-27-2021
The tone control should have four positions. When the control is fully counter clock-wise you still get 32K?
RE: An Introduction and a Philco 90 issue. - cknob - 11-27-2021
Yes 3.2k...3200 ohms...not 32k
RE: An Introduction and a Philco 90 issue. - Steve Davis - 11-27-2021
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
RE: An Introduction and a Philco 90 issue. - cknob - 11-27-2021
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
RE: An Introduction and a Philco 90 issue. - Steve Davis - 11-28-2021
The B+ line (speaker socket terminal 4) is shorted. You will need to trace that line all the way through.
Steve
RE: An Introduction and a Philco 90 issue. - cknob - 11-28-2021
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?
RE: An Introduction and a Philco 90 issue. - Steve Davis - 11-28-2021
Yes, the one reads 20 ohms