Found an RCA CTC5

[Penthode]

I got around to pulling the chassis on this set today. It is pretty well preserved with no tar on the HV components.

I looked at the power transformer(s) on the main chassis and second chassis. The main chassis mounted box is indeed a transformer and not an empty box. This being a 25Hz set, it appears as if the outboard transformer augments the main chassis transformer. I'll trace out the power supply circuit to see what modifications the Montreal factory did. Perhaps the Toronto Reference Library has the notes for the Canadian version of the CTC5-P?

The "Series 700 Notes" posted on the earlytelevision.org website suggests that to service the set, extension cables be employed between the removed chassis and the CRT. I am sure this has been discuused before in this forum: does anyone here know of the thread?

The cables look as if they should be easy to fabricate except for the convergence socket and plug. Does anyone have an extender to loan? Or alternatively, does anyone have the socket and plug to spare from a scrapped CTC5 chassis?

Cheers, Terry

[ohohyodafarted]

Try to find an early Admiral scrapped chassis from a model 30A14CC1 or similar with the separate power supply chassis. The cable that connects the power supply chassis to the main chassis on that set uses the same plug and the socket. The one on the chassis can be removed to use as the female end. This is a very common B&W set and there are probably a number of parts chassis around. Else you will need to find a CTC5 parts chassis and a CTC5 convergence yoke to obtain both the socket and the plug to make up the needed cable.

[Penthode]

Originally Posted by ohohyodafarted

Try to find an early Admiral scrapped chassis from a model 30A14CC1 or similar with the separate power supply chassis. The cable that connects the power supply chassis to the main chassis on that set uses the same plug and the socket. The one on the chassis can be removed to use as the female end. This is a very common B&W set and there are probably a number of parts chassis around. Else you will need to find a CTC5 parts chassis and a CTC5 convergence yoke to obtain both the socket and the plug to make up the needed cable.

Thanks Bob.

In the meantime until I find the appropriate connectore I shall extend the CRT and yoke leads and just leave the convergence coils attached to the chassis and off the CRT until I have confirmed a sensible picture.

[Penthode]

I had a chance to work on the CTC5 today. I am methodically going through the chassis. I traced the 25Hz power supply and this is what I found.

The main chassis transformer was exchanged for a filament transformer only. The box on the chassis is indeed a transformer with 3 secondary windings: two for the 6.3v strings and 5v for the rectifiers. Note the Montreal factory substituted the unique Canadian Robertson head screws to hold the main chassis transformer.

The auxillary chassis has a whopping 20 pound transformer for the B supply only. The auxillary chassis also has a big filter choke and a pair of 80mfd 450v electrolytics which parallel with the 80mfd filters on the main chassis.

The 25Hz transformer will run cool at 60Hz and the extra filtering should make the B supply really clean.

There is evidence of the history of the set's manufacture. The date codes on the main chassis run from the 20th week of 1956 through to the 39th (the latest I could find on a component). The auxillary chassis electrolytics are dated December 1956 so the set's delivery was probably early 1957.

I was amused by the somewhat sloppy modification in one regard: some of the added connections were not soldered! The wire that attached to the rear socket for the primary of the B supply transformer was not soldered as was the B transformer lead that attached to the 5U4 rectifier plates. The connection to the 5U4 actually is burnt from arcing. I suspect the previous owner must have found the set unreliable hence it appears it was not used much. All of the receiving tubes, including the 6CB5 Horizontal Output and the 5U4 rectifiers appear original.