[Penthode]

I worked on the CTC5 again tonight. For the last day since I got the set working, I have been scratching my head over a dynamic convergence problem. The convergence was really bad and the convergence control worked but would not bring the image into convergence.

I could not find anything electrically wrong. I ended up removing the convergence plug and found the convergence considerably better! In fact all the image seemed to require was static convergence. Puzzling over this the only thing I could remember is when disassembling the convergence assembly for cleaning, I may have reassembled it incorrectly. I then reversed the removable horseshoe windings and the dynamic convergence adjusted fine. In fact I am surprised how well it converged, especially after stories I have heard about the difficult adjustment procedure. The only problem I found was having to touch up static convergence frequently as I proceeded through the dynamic adjustments.

I am very grateful the 21AXP22A appears healthy and the greyscale adjustments were no problem. I have a temporary focus pot in place and a 2watt Allen-Bradley pot is on order. Other than replacing most of the paper capacitors and a few resistors and one tube, the set appears in good running order. I shall bench test it for a few weeks to keep an eye on the electrolytics to see if they continue to hold up. The last thing will be to go over the IF alignement when I get my sweep generator fixed.

I have taken some low res photos with my camera phone. I suppose some pictures are better than none. In one photo you will see how I was able to power it up attached to the CRT. I made extender cables for the HV, tuner to IF coax and the deflection yoke. I could not find a suitable donor Admiral set for the convergence socket and so positioned the chassis on a sturdy surface adjacent to the CRT so no extender was required. Similarly the CRT socket was easily attached from the same position.

Note the subchassis B+ transformer. The main chassis transformer is for filaments only. This was for the Toronto 25Hz market in 1956.

Note also the photo of the picture off the screen was via a mirror: my current repair shop is limited in space and the front is up against the wall, hence the mirror.