Another RCA CT-100 discovery B8001599

[Penthode]

I have completed the paper capacitor replacement as well as the disassembly and reassembly of the IF stages to clean out the mouse nest. Last two remaining jobs:
1) Replace/fix the open peaking coils.
2) Arrive at a solution for the dropping resistors (ballast).

Peaking coils: All of the white encapsulated coils are open. The white concrete like covering of the coils was a really bad idea. I managed to salvage two by carefully crunching off the white exterior and fishing for the coil ends. There were signs of green "vertigris" at the wire ends. I managed to find the ends and reattached. However I still need a couple of 1000uH and the 6900uH coils.

I reflected on the design and have dismissed the substitution of different coil values. The I and Q channels have predetermined bandwidths of 1.5MHz and 0.5 MHz respectively. The coils in the I and Q channels facilitate the different bandwidths hence the values must be maintained. Further, the wider I channel has a delay inserted to align the narrower Q channel so it is important to ensure the bandpasses remain as designed to minimize display chroma registration and alignment.

I am awaiting the delivery of a spool of AWG44 wire and contemplate making some coils myself. Once installed, I shall sweep I and Q channels in the course of overall alignment and testing of the chassis prior to attaching the 15GP22.

2) Ballast Resistor: I have decided to mount the 315 ohm 50W and 800 ohm 25W resistors on a heat sink assembly which will plug into the ballast socket. I decided again using the chassis itself as a heat sink and/or mounting the ballast resistors over or near the selenium rectifiers as I want to keep the heat source isolated as much as possible from the CRT bell. I am concerned the temperature source will be detrimental to the CRT.

Also note I decided against using the selenium rectifiers. I have left the rectifiers in situ disconnected and immediately below them have installed a tag strip to which is attached two 3A 800piv rectifiers and a 10 ohm 25W dropping resistor.

I shall be assembling the ballast replacement this week. The electrolytic cans all check okay and the capacitors have been reformed. I should be on target for a first power up this next weekend.