They keep finding me! There are very few sets now on my wanted list and I have stopped actively looking. However....
A few weeks ago I got a wattsapp message from a mate with a picture with the message " U want this". To which a replied "Yes please". a few hours later a soaking wet 20" ITT VC200 arrived!
It was found on top of an old fridge with a load of modern sets outside by the skip of the local house clearance place. the same place that over the years has yielded a few gems! Some of the best sets in my collection are the ones that have 'found me'.
I cut my teeth on this model the place I worked at as a school leaver had hundreds of these and the Pye 169 series out on rental. While dual standard sets were almost scrap on sight single standard sets were rebuilt no matter what!
Over the years I managed to find a Pye 169 but a VC200 had so far eluded me. the odd one appeared on ebay but was too far away to be viable and to be honest it wasn't a must have.
I couldn't refuse this poor orphan, it had got so close to being scrapped so for the last few weeks it has been against a radiator drying out. The cabinet has suffered a bit but is now dry the 'dag is shrivelling and God help the LOPT! The back has changed shape and now appears too big, the back was hanging off when my mate found it.
It will go in the spare room for the time being but I'm tempted to take the LOPT out and bake it at 90 degrees for a day or so. It's not the overwind I am concerned about as it is potted it is the primary that is a concern. Can I run some volts through the primary like you can with an overwind to heat it do you think?
@slidertogrid That's a nice looking set, Rich. Can you get a Pye 368 to find me - model 93, I think?!
I'll certainly keep a look out Mike. The only 368 set I have is a 19" Invicta. 368 chassis sets don't seem to appear that often. What screen size was it?
I decided today to see how viable the VC200 is. A look over the chassis revealed, repairs... it's had a few... All the valves are Thorn.
The LOPT has had a good bake at 70 degrees for two four hour sessions and has been sitting on a central heating radiator since. I refitted it and snipped the mains filter capacitor, removed the boost diode to open the heater chain put a lamp in series with the mains ( my Variac is out on loan) put a meter on the HT line and gave it some power. As soon as the meter showed 100V I switched off and then repeated a few times. Then I left it on and the meter settled at 140V. Checking all sections of the capacitor showed it was holding a charge. I put the valve back in and removed the bulb.
Switching on again I had heaters all apart from the PL504 which is odd as they normally go open if they fail. I wondered if I had a HK short in another valve but not having a circuit to hand I decided to try another valve. A second hand PL504 fitted I had heaters. Then the PL504 really started to glow! Oh dear, no drive... Ever the optimist I swapped the PCF802. allowing the other valves to cool while a had a cup of tea I then tried again.
A rush from the speaker! so I must have line as the LT comes from the line stage. A snowy raster appeared, folded at the bottom but what a good tube!
I can't tune any signals as the tuner is stuck and refuses to budge so that will get some attention tomorrow. First signs are promising though. The basket cases seem to have the best tubes!
A snowy raster appeared, folded at the bottom but what a good tube!
I think I can guess what electrolytic will be hitting the bin next... looking good, Rich.
@cathovisor 😉 Yep - that or do what I have seen done in the past. Wind the lin pots up one end, shift the picture down and piggyback a couple of resistors as required on the back of the panel! "Mrs walker always had a big forehead madam..." 🤣
@slidertogrid We sold a few of those sets when we obtained the ITT dealership in the 1970’s, I can’t remember repairing any of them, if I did they must have been straightforward to fix.
Nice picture on the them when new, looks like you will get it working just like new. 👍
Frank
@nuvistor When I left school I worked for a local firm that had loads of these and Pye 169 sets. The ITT was much more reliable than the Pye ISTR. I can remember changing a few LOPTs, soldering up the IF module and the odd resistor playing up in the audio amplifier and width circuits. When the sets were old in the early 80's I fitted a few tubes, remember Solus with the blue label? Then we started getting those awful Unitra tubes, If it was cheap our service manager would have it! "We only need to get a couple more years out of the mono sets everyone will have a colour set soon." Was his reason for keeping the old sets going on a shoestring.
Anyway this old thing wants to live! All the capacitors read reasonably near capacitance value but every one made a difference when I changed it, either to lin, height or vertical hold so they needed to go. Those Thorn valves are crap! The PCF802 won't oscillate, the PL504 won't light up ( to be fair it could have been killed by the no line drive) The boost diode was the wrong one and also caused the picture to balloon depending on brightness and the PCL805 takes ages to warm up. The PCL86 is holding up though!
The line stage capacitors are still original but I think I ought to change the boost cap to protect the LOPT... The set now gives a very good picture. The picture shape isn't quite perfect but it is good enough, there are no magnets top and bottom so there is nothing to adjust there. I think it will do...
I think I ought to change the boost cap to protect the LOPT... The set now gives a very good picture.
I think you should, says he remembering the cap in Decca Bradfords! What did you do to free up the tuner?
@cathovisor It's one of those 'rack and pinion' types that Philips were so fond of, the one with the return spring around the gear. The tuner itself was free but a little 'scratchy'. I lubricated the bearings with switch cleaner followed by a touch of light oil.
The mech was stuck solid so it needed a clean and lubricate being careful to work the cams back and forth until they became free. I used aerosol light grease for the final lubricant. It now works and returns well and so far has stayed on tune.
There are a couple of previous repairs I am tempted to tidy up, one a resistor in the row of 'dropper' surge limiters etc. It has been replaced with two I'll check the resistance is right and go from there. It is in one of the HT lines so probably not that critical. Then the little white plastic capacitor stood up near the line osc valve, that is annoying me but do I leave it as a period repair? I have seen worse... Much worse!
Then the little white plastic capacitor stood up near the line osc valve, that is annoying me but do I leave it as a period repair?
If it ain't broke... however, it does look rather untidy.
Also, the PCB seems to indicate a preferred orientation for C71 as I'm assuming that "OF" refers to Outer Foil?
Yes I wondered if the extra hole was to stand the capacitor up but it is an extra connection for the right hand end of the capacitor so it looks as if they planned the panel to be able to take a longer capacitor. There are a couple of places like this.
I hadn't spotted the OF marking but yes I think you may be right what difference it makes I don't know.
They keep finding me! There are very few sets now on my wanted list and I have stopped actively looking. However....
A few weeks ago I got a wattsapp message from a mate with a picture with the message " U want this". To which a replied "Yes please". a few hours later a soaking wet 20" ITT VC200 arrived!
It was found on top of an old fridge with a load of modern sets outside by the skip of the local house clearance place. the same place that over the years has yielded a few gems! Some of the best sets in my collection are the ones that have 'found me'.
I cut my teeth on this model the place I worked at as a school leaver had hundreds of these and the Pye 169 series out on rental. While dual standard sets were almost scrap on sight single standard sets were rebuilt no matter what!
Over the years I managed to find a Pye 169 but a VC200 had so far eluded me. the odd one appeared on ebay but was too far away to be viable and to be honest it wasn't a must have.
I couldn't refuse this poor orphan, it had got so close to being scrapped so for the last few weeks it has been against a radiator drying out. The cabinet has suffered a bit but is now dry the 'dag is shrivelling and God help the LOPT! The back has changed shape and now appears too big, the back was hanging off when my mate found it.
It will go in the spare room for the time being but I'm tempted to take the LOPT out and bake it at 90 degrees for a day or so. It's not the overwind I am concerned about as it is potted it is the primary that is a concern. Can I run some volts through the primary like you can with an overwind to heat it do you think?
It's nice to see the progress on this set, I do wonder if it developed a fault at some point & got put to one side rather than being repaired or scrapped, which might explain the low hours tube.
I've read a few anecdotes on independent rental shops buying sets second hand & reconditioning them.
Some dual standard sets had the 405 line circuits isolated, usually ones where the channel buttons could be set to just tune to 625 lines.
I'm not sure the set is low hours, it has had a fair few previous repairs, including a complete set of valves. That said I do wonder if the valve replacements were actually necessary, especially as they were all Thorn branded. Were they all fitted at the same time or replacements as needed? Maybe the set was owned by a Thorn rentals group or was it a Thorn rentals engineer "doing up" a set to flog with a pocket full of 'free' valves?
The VC200 used grid modulation could that be why the tube survived so well? The CVC series of colour sets were also 'kind' to their tubes, even the Toshiba ones lasted quite well.
I must admit the condition of the tube did surprise me when I first got a raster, these 20" and 24" 'square screen' tubes often defocussed towards the edge of the screen, Especially the Mazda Gold star ones in the 1500. Why Thorn bothered to fit a focus control I don't know! A convergence yoke may have been better!
That's a Philips LOPT. All insulation is polyester or epoxy. No need to bake it. Probably not a good idea.
If the set has stabilised scan make sure it's set correctly by measuring the boost voltage. If it's set too high the epoxy potted overwind will go shorted turns very quickly.
Chassis is reminiscent of a series 11 Astor, except, being Oz, the 11 has a mains transformer.
I had a 17" square corner Mazda / Ediswan CRT in an Oz all SS Thorn portable about a year or so back. Posted its story on this site.
Focus was very uniform over the entire screen. There was a focus pot with a 500 volt range but it had virtually no effect on that tube. And I checked it, right up to the tube base!
That TV is currently working displaying old newsreels in an installation in the Melbourne Art Gallery.
@irob2345 Strange that KB should use a Philips LOPT and Tuner. I suppose it saves production costs. I will heed your advice about checking the boost. There is a procedure to set the boost and EHT in the manual. Luckily I still have Mick's EHT probe.
I was careful not to overheat the LOPT when I baked it, It was just on 70 degree 'plate warming' setting. My original plan was 90 degrees but I didn't want to risk cracking the former. I was careful to allow it to cool slowly overnight in the oven rather than risk shocking it by removing it into a cool room.
Strange that KB should use a Philips LOPT and Tuner.
Not really Rich, they're just an "off the shelf" component - I'm sure I have some older Philips databooks that list them as such.
In Oz you had Philips, MSP (AWA) and Rola making deflection components, not counting Pye who made their own and Telequipment (Ferris) who made excellent replacements. EMI (HMV) used Rola, MSP and Philips at one time or another.
There were only 2 Philips LOPTs in 110 degree - NT3101 and the newer NT3102. I'd love to find a cache of either of these, they can replace just about anything, even in 90 degree sets. And because they are not paper and wax they don't have a use-by date!
Philips had a factory in the NE of England, I think Washington but could be wrong. They made scan coils, presume they made other inductors aswell. Mullard also had a CRT factory in nearby Durham.
https://www.theguardian.com/business/2005/mar/02/17
Frank
