Re the metal film resistor, that sounds like flashover damage.
Used to take out the colour difference clamp diodes in the National Panasonic TVs that used the RCA deltas.
We'd prevent a repeat performance by cutting all the aquadag grounds except for the one running back to the tube socket.
After several recent distractions I pulled the ITT back on to the bench today. A couple of grey Plessey 0.022uf caps and a blue and white 0.0033Uf TCC were replaced, I'd ordered these previously as I had no stock. These made a big difference to the operation of the frame linearity controls and improved matters no end but still had an issue with not being able to centralise the picture with the frame shift pot. I was going to replace the 20 ohm pot but after removal I noticed that the circuit diagram didn't match how it was connected on the PCB.
This CVC5 must be an early version as the pot although 20 ohm is wired as a variable resistor rather than a potentiometer. As I had already been over the associated components and found no issues I decided to modify the circuit to the later design. Bingo! perfectly centred picture. One thing I have noticed is that the height and lin pots seem to be very interactive with the frame hold, move any and the hold needs to be readjusted. The lock is in no way weak and locks solidly, is this normal?
I can see why these sets had a lot of fans, apart from some areas of the line output cage (frame shift pot area!) and the IF panel these are very nice to work on. Sound quality from the PCL86 is quite punchy and now with the R-Y sorted Carole looks to be in the pink. A very pleasing addition to my collection.
John.
I once visited the late Chas Miller at his home and their main TV was a CVC5. Apparently they were always very gentle to their tubes and produced excellent pictures long after other sets needed a replacement. My first experience of colour TV in our home was a loan CVC set (the one with touch selectors and the push-button tone control) whilst our mono set was out of action but my parents decided against it on both cost and "it sticks out too much into the room" grounds.
@jayceebee That certainly is a good picture! I really liked the CVC5/9 they were reliable, predictable and as you say with the exception of removing the IF panel, easy to work on. They were the last delta gun sets we had on rental in fact a CVC9 was still out in the '90s it hadn't had a service call for over 10 years so had missed being updated. It must have been over 20 years old before it came back. I really should have saved it in retrospect!
Excellent sets. In my time in the trade, I never saw one with a duff tube.
... in fact there's a little CVC5 shaped hole in my lfe
@doz You must have been lucky and missed the 20" sets fitted with the Toshiba tube. Admittedly they were few and far between. I also have a dim maybe wrong, memory of some 20" having Hitachi tubes, maybe? I don't know why other than there may have been a shortage of 20" Mullard tubes during the "Boon"? The Toshiba tubes turned up in the Hybrid and early solid-state GEC sets as well so maybe that was the reason. It was a waste of time boosting a Toshiba tube it would go down before you got back to the van!
True to say the 22 and 26 inch sets with the red label Mullard went on forever!
@slidertogrid Luckily the Japanese manufacturers improved their CRTs, quite a few 1980s sets were in everyday use until the digital switchover.
I was given an early 1990s Mitsubishi by one of my Dad's friends which served me well as a second set, using a set top digibox after the switchover & a universal remote control because the original one couldn't be found! I had it until I bought a digital set for my main TV & it had to go as I had no storage space. Stupidly I gave it away with the original brochure.
Yes I agree the Japanese PIL tubes were very good usually lasting the life of the set. The National (Panansonic to younger members) delta guns were also good. Often a 85G would still be going strong at well over 10 years old, many having never had a repair. I sold Toshiba sets after I fell out with Ferguson which must have been mid '80's and I cannot remember ever changing a tube.
We saw very few Toshiba delta CRTs in Oz but the 1st gen inlines onwards were very long-lasting tubes UNLESS the heater voltage was above 6.3 volts. Even 6.5 volts would drastically shorten their lives.
My late mum had an early Pye T30C with a self-converging 63cm Toshiba CRT. This TV was in use 8 to 12 hours a day for 25 years (nearly 100,000 hours!) and the CRT was still good when, after she passed, the TV was destroyed in a flooded garage. It ate triplers though - I must have replaced half a dozen over the years, mostly broken down to the mounting screws.
