What could Account for This? RCA 9TC-240 Power Issue

[Chris K]

I'd like some advice regarding removal of the TV/Phono switch from the circuit. It's not exactly part of the title of this thread but I don't want to start another thread on the same TV...if I understand SOP here. If I should move this to the start of a separate thread, then please let me know.

Yesterday, the Riders service manual I purchased, Volume 4, arrived at my house. In it is the wiring diagram and schematic for the 9TC-240 with the KCS28B1 chassis. The switch on the wiring diagram and schematic is pictured below.





So if I understand what has been described earlier in the thread, if the switch is moved to the phono position, the TV brightness control ground is interrupted and the screen goes dark. There's still HV however. The sound circuit then comes out of pin 5 of the 6AL5 discriminator as coaxial to the switch where it picks up audio input from the RCA jack and is brought back into the sound circuit as a grounded coax line. Around there I get lost! To me it seems the signal goes to terminal 3 of the volume control and out of terminal 2 as coax to pin 1 of the 6AV6 bias clamp???

Below is the WD at the volume control.



The yellow and green coax are from the switch.

I need to understand how this all works with the goal being removal of all the switch wiring and circuitry interruptions. I'd like to just cut it all out and wire the sound like any TV would be without this feature.

[bandersen]

Originally Posted by Chris K

So if I understand what has been described earlier in the thread, if the switch is moved to the phono position, the TV brightness control ground is interrupted and the screen goes dark. There's still HV however. The sound circuit then comes out of pin 5 of the 6AL5 discriminator as coaxial to the switch where it picks up audio input from the RCA jack and is brought back into the sound circuit as a grounded coax line. Around there I get lost! To me it seems the signal goes to terminal 3 of the volume control and out of terminal 2 as coax to pin 1 of the 6AV6 bias clamp???

Yes, pretty much. They way the drew the switch is a little confusing. The switch element go left/right not up/down.

* Ground lug 3 of the brightness control.

* Connect the two ends of the coax together so that the end of R215 is going to C184.

[Chris K]

Originally Posted by bandersen

Yes, pretty much. They way the drew the switch is a little confusing. The switch element go left/right not up/down.

* Ground lug 3 of the brightness control.

* Connect the two ends of the coax together so that the end of R215 is going to C184.

That's what I thought looking at it. So all the capacitor and coaxial stuff going on around the volume control, all of that stays in place? That's where I got lost!?