Here is a quick peek under the 7M112 chassis. It's uncluttered and it should be easy to work on.
The set has two selenium rectifiers and a sturdy (and clean!) turret-style tuner with 6J6 and 6BK7 tubes. The HV output section is also under the chassis and I removed its (solid steel) cage for this photo. The TV actually has 18 tubes including the CRT, even though only 15 are shown in the back-cover diagram.
Someone serviced this TV not too long ago. Notice the new resistor under the 1B3GT HV rectifier socket. I have exactly the same type of resistor in my parts boxes.
Here are a couple of other recent replacements:
The electrolytic is piggybacked in parallel with a can electrolytic rather than taking the old cap out of circuit.
I found another new electrolytic wired between two pins of the 6AH6 video amp. The red Big Chief cap looks like an older replacement. The original paper caps are a brand that I hadn't seen before: "Good-All Marbelite."
I made a couple of cursory checks and the B+ voltage seems reasonable. HV measures only 8.5KV, where that CRT normally wants something like 14KV.
The TV is still full of ancient electrolytics and paper caps, so I'm not going to burn a lot of time diagnosing specifics until it has been recapped. Lacking a good place to work, who knows when that will happen?
It's interesting to peek underneath, anyhow. Yes, it's an inexpensive, series-string set, but the factory wiring is tidy and the overall build quality looks decent. It's surprisingly sensitive, all things considered. When I first powered it up, it made very clear audio receiving a signal from my in-house transmitter, without anything connected to its antenna terminals.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html