Murphy V200 restoration

[murphyv310]

Hi Folks!
I have just started to work on my very sick looking V200.
Last Monday I removed the chassis from the cabinet and removed the CRT (very easy); after a good look round the chassis I decided to even see the components - I would steam clean the whole thing.

I protected the loptx and tore in! The result was excellent: you now could see everything, including some ropey repairs from the past.

I let the set dry out over a couple of days in a very warm and airy place then soaked the whole set in WD40; this was then blown about with the hairdryer.
I refitted the tube and left the set till this afternoon. There were no valves in the set nor an HT rect, so after going through my valve stock fitted 12 new ones and 3 used ones, the U25 was still fitted to the loptx.

A new old stock BY100 and surge limiter were fitted, and as I do with all sets I restore I bridge out the heater dropper and metrosil so the heaters warm up at a lower voltage. I find this is kinder to the set when building up the voltage on the variac, but I keep a close eye on the total fed to the heater chain. The on-off switch was o/c, so it has a temporary link.

I first fed the set with 20v; this gave 25v dc which I left for 25mins, after this I fed the set with 50v, but the HT only rose to 35v at this point.
There would be no loading from the valves, so a quick feel about the capacitors revealed a 0.1 TCC waxy getting hot, as it was on the HT line - a quick snip pushed the HT to 65v.

Over the next 30 mins I gradually increased the input to 100v.
I had no further problems with the HT dropping until I could start to see heaters, I then advanced the input to 110v and the line burst into life, by the time I was at 130v with all the valve glowing ok I had about 3KV EHT. Remember the set is running on low HT, as this is the way I always bring a set on.

I connected the heaters up and went up to 200v - by now I had a reasonably bright white line!
So I think tomorrow I will work on the frame stage.
Today was very encouraging
Watch this space

[Heatercathodeshort]

Hello Trevor,
Brave man with such a mess! I had a frame collapse on mine and it was due to O/C height and frame hold controls. Not easy to spot. Good luck with this one. Real quirky set. Regards John.

[murphyv310]

Too right John, one of the pots (frame hold) fell apart.
I really didn't think this set would do anything. I was going to just try 230v but had a little spare time so did as above.
Trevor

[murphyv310]

Hi.
Here are some photos of the chassis.
Trevor

[murphyv310]

Hello.
I didn't have time at the weekend to do any more to the V200, but I had an hour tonight. I discovered that the 100 ohm across the two 10P14's had been linked out effectivly shorting out the heaters.
After bringing up the mains I have a nice full scan and bright raster with good focus, so the tube seems ok. I don't know what channel the RF unit is but no doubt it will need some work though.
So far so good.
Trevor

[murphyv310]

Progress report!
I decided to spend a few more hours on the set today.
I replaced some more caps in the IF and frame stages, by this time I was getting a picture of sorts, then one of the "new" 10P14's failed; it developed a heater cathode short (sorry John).
I didn't have another, so I made up an octal-to-B9A adapter and fitted a UL84. I used it in the frame o/p as the focus range was wrong with the UL84 in the audio.
The anode load for the line osc was way over a meg and some other values were way high so these have been changed.

So here are some photos: the set has a Channel 3 tuner, the tube is a little down but is improving with time.
Trevor

[murphyv310]

Update
One of the problems I had with the set was ticking from the line stage along with hooking at the top of the picture.

I noticed that the fringe mod had been done and as the set had come from Kirkudbright, I could understand why it was done (70 miles from Kirk O'Shotts).
After taking the mod out this cured the the fault; no doubt the time constants are shortened on the mod.
Trevor