21CT55 Screen-Shot Test

[Tomcomm]

Well after my "21CT55 Restorer" vs "21CT55 Enhancer" manifesto has been likened to my 1957 Austin Healey V8 engine Enhancement history, let me revisit some ancient history:

Where I'm Coming From Feb 2003

I don't know how long you Modified Healey guys have been hot rodding. I suspect that most of you have been messing with cars continuously since you were a kid.

Well, I’ve always been an electronic geek. I didn't even have a driver’s license or owned a crescent wrench until 1953, when at 18, I got a job as an electronic technician at RCA, West Los Angeles, and was forced to get and repair a car, a '41 Plymouth, yuk, But then I was hooked! In '54 with a friend's big help, I installed an original 303/348ci '49 Olds Rocket in my second car, a '49 Plymouth fast back business coupe ( I'm a slow learner) With a '37 La Salle 3 spd top loader this was the hot street sleeper, even against the hot '32 Ford 4x4s, '55, '56, '57 Chevys and Buick Centurys.

In early 1957 I bought my third car, a ‘54 Austin Healey 100 4. I liked the car, but after the Olds Plymouth it was a zero performer. Three months later at 22, I pulled the monstrous Olds/La Salle combo out of the Plymouth and jammed it into the cute little British roadster. It was an act of brutal incest, I admit.

I did this 6 month conversion entirely by myself in a garage I rented with four SB Chevy guys who were sure I was crazy to do such a stupid thing as putting an obsolete 8yr old 700+# engine and 20yr old obsolete 3 spd in a new 3yr old 2100# British roadster. Of course I would have preferred a 500# SBC with the latest 4 spd but none of these guys or anyone else would sell me one reasonably, they wanted them for themselves.

It weighed 2486# curb, had a 48% front vs 52% rear weight distribution and was really quick off the line. One of the Chevy guys was Bones Balough of NHRA fame. We went to all the local So Calif drag strips where we cleaned up,

We were active in drag racing from late 1957 to early 1960 in modified sports, turning 112mph in 12.5sec best. The modified Corvettes were our only competition but couldn't beat Bones off the line due to my 30% engine setback. Then we beat a Buick V8 Doretti modified sports and he protested my engine setback. The NHRA forced us into the altered competition roaster class that had enormous engine setbacks; huge slicks that ran in the 11's at 130mph.

This put me out of drags and the car became a daily driver until 1964 when I installed the 394ci/ 418ci '59 Olds and also did the Cobraized nose. I took it to the drags only once with the "new" engine but couldn't launch it with the street tires so I turned 13.2 at 118mph. Although I could beat the SB Cobras, the new BBs had come out and were getting faster. I realized I couldn't beat the modern 427ci/ 4 spd with my ancient 418 engine/ 3 spd so I simply retired the car in 1967, consigning it alongside the garage where it deteriorated into a decrepit rust bucket. I was now totally out of the modified sportscar scene while pursuing a career in electronics and raising a family.

In 1999 at 65, I completely retired and pulled the 45yr old heap from its 32yr grave and started a "1964 Period" restoration. With the V8 engine and body alterations (Healey people call it an abominable desecration) I decided to restore it to its 1964 configuration, complete with 43yr old engine and 63yr old trany. I would retain the original '54 Healey wire wheels and 70 series tires all around. I also decided that in no way would I flare the fenders for big tires. Any enhancements to the engine would be limited to items that were available before 1965. I realized that these restrictions would make it extremely difficult to compete with the faster Modified Healey members but I would give it the good shot.

And so it is today. I would respect the car as a piece of early Healey history and just make it run well. At my advanced age, I can't start another life consuming, advanced car project.

[Tomcomm]

217-1793_IMG by Tom Schnerk, on Flickr

[Tomcomm]

HV-cage-rebuilt by Tom Schnerk, on Flickr

[Tomcomm]

b!00000119 by Tom Schnerk, on Flickr

[Tomcomm]

This is first pix of my 21CT55 using a repaired CTC20 FBT. Note that the VTVM shows full scale reading on 30 range with 1000 divider at the crt anode or 30,000 volt range. The VOM shows 200 on the 500ma range or 200ma current at the HV .5amp fuze which is the same as measured at the horz output cathode. This indicates the CTC20 FBT circuit is more efficient than the original 21CT55!
This pix was taken 1/2/2016, over 5 years after the original FBT failure.

Presently the 21CT55 is inoperative since the repaired CTC20 FBT failed due to arcing of the repaired silicone covering. Not to worry, I've got an extra CTC 20 FBT in it's original RCA box. All I got to do is make wire to wire switchover from old to new FBT, what could be simpler, eh??


b!00000119 by Tom Schnerk, on Flickr

[Electronic M]

With your second CTC-20 flyback, make sure NOT to run it above 25KV. 25KV is what it was designed to run at, and RCA tended to run their flybacks at the top end of what they could survive...Pushing it beyond that is asking for failure.

[Tom9589]

Tom, why did you apply silicone to the first CTC20 FBT?

[Tomcomm]

The HV rectifier plate socket on the transformer top was open circuited. Should have measured around 600 ohms to the horizontal driver plate. Since the FBT was obviously never soldered in I elected to attempt a repair rather than send
it back to Mouser. This entailed removing the plastic coil covering and resoldering the very fine "horse hair" wire from the coil ending to the rectifier socket. It then measured 630 ohms which was about right. I decided to recover the coil with Permatex Ultra Blue instrument grade silicone sealer to protect the very fine coil wire. This fix worked fine for all of my "Performance Enhancement" experiments for the last 8 years as well documented in this VideoKarma thread.

[Tomcomm]

Point of interest: What does an unmodified 21CT55's CRT anode voltage run with cutoff screen and the HV regulator pulled, with 130V AC Line input? Anyone?

Seems this worse case scenario must have been envisioned by RCA engineers before they got it released to production. What sort of catastrophic failure of non-tube replaceable parts would they tolerate? The CRT and FBT for sure are major items of concern and must be specified with at least 10% safety factor.

My 21FBP22A CRT is spec'd at 27000 volts max. My 21FBP22A CRT is set to run at 30000 volts with 120v AC or 11 percent over max spec for demonstrable maximum picture quality. I accept this risk vs performance tradeoff.

[Electronic M]

Most makers assumed that a set would not be running for a long time in failure mode...just because you can run an engine for a couple of minutes with no oil or coolant in it without it burning up doesn't mean it won't if driven in that state for a prolonged period.

You've already seen the original and 1 replacement burn up. Shouldn't that tell you to dial it back a bit? Even 3-4KV (lets say a tech had a HV probe that was 1-2KV off and set it for 26-27KV) less than you've been running it at will have only very minor effect on brightness, sweep and general image quality and will be at least reasonably close to factory specifications. Even before the X-ray alarmists many makers in their service literature stressed proper HV adjustment. New flybacks don't grow on trees; why not cherish what may be the last one you can find?

[Tomcomm]

[Tomcomm]

[freakaftr8]

I'm getting warnings on bandwidth limits. I dont use PB anymore and wont let me login. Lol

[Tomcomm]

Copy of 39 by Tom Schnerk, on Flickr

[Tomcomm]