Murphy 12" V180C console 1950

[Heatercathodeshort]

The last two.

[hansomcommon]

Fabulous, well done, this is really a magic set, Murphy take the biscuit for the oddball but superbly engineered receivers, I admire the massive work you have done here!

[FERNSEH]

Hi John,
Again, I've something to aspire to. Those pictures are fantastic. Even more so when you consider the CRM123 CRT is intended for 9KV operation. Now that my own Murphy V180 has a strong cabinet aided of course by those brackets it's about time I made a start on the chassis.
The set is being discussed in a separate topic on this Forum.

DFWB.

[andycapp]

Lovely old TV, lovely job done, something to aspire to, hopefully will see some shots of it all back in cabinet. Andy

[Heatercathodeshort]

Originally Posted by FERNSEH

It's about time I made a start on the chassis.

OK David, time to stop playing woodentops and get a test card on that chassis

Seriously it's a lot harder to repair a cabinet than it is to bring the innards back to life. The chassis will be easy after all those adaptor plates you have fitted to the cabinet.
Good luck with it David.
Yes Andy, Just needs a clean up for the time being. Regards, John.

[Tazman1966]

Once again another resounding success story. I must come down and see it in the flesh.

[Heatercathodeshort]

It just occured to me that I didn't post a picture of the receiver unit in the service position. The sync is connected to the timebase panel by a single pin and socket that can be seen to the left of the final vision I.F. transformer.
One bad design point is the length of the lead to the grid of the CRT. It is short by about an inch when in the service position allowing a heavy strain on the CRT base unless the connector is removed. This could of course be extended. [I used a croc lead while working on it].
Thanks for all your comments. It was David working on his cabinet that prodded me into action especially as he opened the thread a day before my example arrived. All good fun. John. PS This was supposed to be a winter project...

[mark pirate]

Great result John, I look forward to seeing it back in it's spruced up cabinet.
Let's hope David's set comes out as good as yours

PS This was supposed to be a winter project...

I can always deliver my Murphy V150 if you need something to keep you busy...

Mark

[Freya]

I can always deliver my Murphy V150 if you need something to keep you busy...

You just don't want to change all those Hunts in the I.F. stages Mark

[Heatercathodeshort]

The Murphy V150 is a vile little thing. I have a matched pair. One 'works' and the other has never had mains applied since 1960 and I've spied a 2V isolation transformer bolted to the cabinet rail..
I'll certainly have a go at it Mark but must complete a Decca 131 I am restoring for the BVWTVM first.

[mark pirate]

I was only joking John
But I would like to bring up My HMV 2811 when you have the time.

You just don't want to change all those Hunts in the I.F. stages Mark

I don't actually mind replacing those little cockroaches, but I have more deserving sets to use up my supply of caps on!

Mark

[brianc]

Super work again and a very tidy result. My V116 had the same cableform down the RHS but unfortunately, being an earlier set, half the form used rubber insulation which had to be replaced. The V180C looks to be all in PVC, a much more stable stuff.
Nice one John

[Restoration73]

This is very inspiring. I don't know which of my Murphy's to do first, though. They're a
V210, V216C, V330.

[Heatercathodeshort]

When finally testing a vintage television receiver for long term stability it is advisable to soak test it for around a week. Odd symptoms often due to leaky components or poor insulation will reveal themselves and can of course in the case of 60 year old plus line output transformers be a disappointing nuisance.
The Murphy V180C is no exception and I have noticed that over the last few days, when switching on in the morning there has been an intermittent partial collapse of EHT for the first ten minutes or so before settling down to it's excellent performance.This morning The picture was just a blur on switch on and the EHT had dropped to 4kv....
Add to this a very faint crackling sound from the LOPT and the outlook did not look good. It was time to investigate the reason and I must admit I had a hunch what the outcome may prove to be.
Early Murphy line output transformers were totally enclosed in a cardboard box, literally crammed in! This was lined with Sorbo rubber panels to absorb the 10kc/s whistle that was so annoying to those that could here it clearly.
The transformer was removed from the chassis and it was only the work of moments to extract the transformer from it's rubber coffin. An examination of the Sobo rubber panels revealed all and one of the pictures shows the low resistance track between the tags connected to the line output valve and the EHT pulse to the U24 rectifier.
It measures around 500K and the tracking lines can easily be seen.
With the transformer naked on the bench it was connected with extension leads to the chassis, an instant picture appeared a very short period after switch on. With the increase in moisture in the air the 60 year old rubber had become conductive. I will make up some new panels with polystyrene to eliminate the problem for good. The transformer itself is in very good condition and looks as fresh as the day it was wound back in 1950. It also runs very cool so there is hope! Regards, John.

[mark pirate]

Good news that the LOPT is ok, I wonder if the 'insulated' enclosure gave any problems back in the day?
Later Murphy sets of course enclosed the LOPT in an oil filled can, this would have been more effective against moisture ingress, as well as muting the line whistle.

Mark

[Heatercathodeshort]

I don't think they would have given problems when in general service Mark. The rubber had hardened considerably and probably sucked in dampness over the last 50 odd years. It's a very long time, more than a lifetime for many. Back in 1950 I was 2 years old when this receiver was manufactured in Welwyn Garden City. It was very obsolete by 1960, just 10 years later. Murphy Radio had only just over a year to run as a company, crashing into the buffers by 1962. Great shame. John.

[Lloyd 1985]

Picture's looking good on that Murphy! Shame about the LOPT housing breaking down. I'll have to keep an eye on mine, just in case it tries to go the same way, mine looks to have been stored somewhere damp which probably won't help.

Regards,
Lloyd.

[Heatercathodeshort]

Worth having a look Lloyd. It's not too difficult to get out of it's box. Just a couple of turns on the strap securing the card box once you have got it out, 3 wires, one to HT and the others to the scan coils via the width control, plus the heater connections to the U24. It falls apart once its unclamped. The top right securing screw behind the width control inductor is a beast to locate and remove. There isn't a screw in the bottom right as might be expected. It's fine now even after starting on this misty damp morning. [Sounds like an old Ford Popular] Regards, John.

[brianc]

Good one John. It makes me want to get my 116 out of its slumber! Perhaps next week.

[Heatercathodeshort]

You have to laugh. It's either that or cry!
To be honest I was waiting for this to happen and the slight focus drift mentioned earlier in the thread was slightly more than was normal for this circuit.
I continued to soak test the chassis and gave it a look in from time to time.
After around four hours on Sunday the EHT rapidly reduced over a five minute period and finally collapsed to zero. Yes of course it is the LOPT overwind developing S/C turns. The resistance of the windings is still exactly as it states in the manual but I have never taken any notice of LOPT resistance windings and did my own little test.
An Ekco TMB272 transformer was to hand and with the original disconnected I connected the primary winding between H.T. and the anode of the EL38 line output valve. On switching on the line timebase brightened up giving a nice glow in the U25 that was still mounted on the TMB transformer. This confirmed the breakdown of the Murphy transformer but all was not lost.
A rummage through boxes of odd transformers produced an example from the MK1 version of the Ekco T161. A quick look at the circuit confirmed that it was almost identical with the Murphy and it was soon hooked into circuit.
The picture produced is excellent, identical to the original transformer and required just a small adjustment to the width inductor.
The EHT measures a fraction over 7.5kv and is stable over an 8 hour soak test. Another interesting sideline is the focus holds 100% over this period proving that the EHT must have been dropping a very small amount, just enough to cause focus drift during the original trials.
There is plenty of room on the power supply chassis to mount this circular can transformer and a very neat job could be made of it but I think Mike Barker may have another transformer to rewind as I would like to keep the set original.
All part of the fun and a very interesting learning curve as this LOPT fault did not occur when these receivers and many others were in service. It's a combination of dampness, change in the insulating properties of pitch and breakdown of the interleaving tissues separating the winding layers of these earlier non Ferroxcube flyback transformers. Regards, John