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Old 18th Oct 2018, 9:16 am   #1
Heatercathodeshort
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Default Crazy Murphy 12" console V210C 1953.

I spent about an hour clearing up the workshop. It was in a mess after sorting out the 16" Ferguson 989T. Resistors, Capacitors, test leads, service manuals, jump leads, tools and knotted test leads. It's nice to start afresh with each job with everything needed to hand.

Interlace tried to help but as usual just added to the chaos putting valves in the wrong boxes and just replacing resistors in the first drawer that came to mind. He cannot read the colour code..yet.

The vacuum cleaner was the last straw, great fun for him but it took me half an hour to recover all the EF91 valves he had managed to suck up with the Henry from a box under the bench. I banned him from the workshop until I had cleared up the jumble of components and must admit it had slipped my mind that I had done so..

About half an hour later I suddenly I heard a dragging sound followed by a bump. I opened the door to see a Murphy V210C chassis dumped at the bottom of the three steps that lead to the workshop.

Apparently he had stormed off down to the bottom of the plot taking delight frightening the Mr fox and his rabbits. Eventually boredom set in resulting in him rummaging about, eventually discovering the chassis dry stored in one of the sheds. He had literally rolled it across the grass then dragged it by it's mains lead to land on the paving.

I must admit I was somewhat amused. All this talk of Murphys namely the V310 and V410 must have stimulated something! He can't read of course, at least I don't think so. Mind you he has developed a great interest in old service manuals. There is more to that Orangutan than meets the eye.

Well, as he had gone to all that trouble I thought it only fair to place it on the workbench with a view to plugging it in.

This range of Murphy chassis is without doubt the most bizzar ever produced. It was known as the 'Aeroplane Chassis' due to it's similarity in appearance to the aircraft rotary piston engine known as the Merlin, so familiar during WW2 just eight years before the birth of this receiver.

Basically the chassis consists of two wide aluminium rings, one at the front and one at the back joined by four chassis angled within the rings. This is difficult to describe but can be clearly seen in the pictures. The CRT is fitted through the center.

The line timebase takes up two of the chassis which also contain the mains metal HT rectifier, the choke and main smoothing components. The third, RF front end strip with two RF amplifiers [10F1 valves and the frequency changer [10C2] plus video and sound output stages.

It was necessary to exchange the three valve plug in front end when changing BBC channels 1-5. Five different units were available. A very expensive way of carrying out a simple tuning procedure. Quite why this was done with a superhet we will never know. The words, Murphy madness come to mind!

Chassis number four contains the sync separator and the frame timebase/output.

The line timebase is a self oscillating arrangement employing the massive Mazda 20P1 line output valve. The design of the 20P1 was optimized for self oscillation/output operation and they are very stable in service. A U281 boost diode supplies a respectable 375v to the boost rail. The line output transformer is a large oil filled can with an external U25 wire ended EHT rectifier. Externally there is no trace of leakage, the can being devoid of oil deposits. The EHT of around 7kv is smoothed by a reliable 500pf ceramic capacitor.

Interlace was engrossed in the service manual and had already noticed a cuckoo in the nest, namely a Radiospares 2v isolation and 20% boost transformer bolted to the bottom rear hoop. He kept poking at it as if I hadn't noticed it.
The tube fitted was the usual Ediswan/Mazda CRM121A. The correct tube for the V210C is the CRM123 which is aluminised. I can only think it had been changed during it's life for the earlier tube. It had a nice black getter with it's heater connected to the 2v winding, no boost, so I guess it was suffering from the Mazda fault of that period, a heater cathode short. A test proved that it was.

These 2V triodes were notorious for developing heater/cathode shorts and low emission. Many lasted less than two years but incredibly the top three manufacturers, Murphy, Ekco and Ultra put up with this poor service life for many years. Murphy did complain to Ediswan in 1952 but were only told that 'things would improve in the future'. The Mazda range of television valves were of good quality with an exceptional service life but were quirky and somewhat old fashioned requiring two heater chains, 100M/a and 200M/a.

They did have a rectifier problem and the early boost diodes needed a highly insulated winding on the mains transformer to supply heater current, as did certain EHT rectifiers. Their expertise came to the fore in the manufacture of RF and audio output valves. Some very fine valves were produced that led the field for several years until the competition caught up.

I'll let you work the pictures out yourself.
Part 2 to follow soon. John.
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Old 18th Oct 2018, 10:47 am   #2
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Default Re: Crazy Murphy 12" console V210C 1953.

I love the appearance of these chassis, I think it should win awards for the most interesting chassis design! You just need an Ekco A22 chassis to go with it now

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Old 18th Oct 2018, 4:55 pm   #3
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Default Re: Crazy Murphy 12" console V210C 1953.

Blimey that's a bizarre chassis. I'd say The Man With The Pipe had something other than St Bruno in the bowl the day they came up with that.

Being pedantic, the chassis is less like a Merlin engine and more like a Vulture.
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Old 18th Oct 2018, 5:08 pm   #4
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Default Re: Crazy Murphy 12" console V210C 1953.

Quote:
The Pipe had something other than St Bruno in the bowl
A Canadian design? Back on topic, marvellously quirky, easy access to the bits, being round did it have vertical, horizontal and roll hold controls. I love it.
 
Old 18th Oct 2018, 5:19 pm   #5
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Default Re: Crazy Murphy 12" console V210C 1953.

A mad design, even by Murphy standards!
Makes my V136C look conventional
I will be following this thread with great interest.

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Old 18th Oct 2018, 6:07 pm   #6
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Default Re: Crazy Murphy 12" console V210C 1953.

The entire assembly can be taken out in one piece and it does give access to every part so should make servicing easier.
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Old 18th Oct 2018, 8:50 pm   #7
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Default Re: Crazy Murphy 12" console V210C 1953.

What a fascinating chassis, I bet it would run circles around any other contemporary design.

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Old 22nd Oct 2018, 4:45 pm   #8
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Default Re: Crazy Murphy 12" console V210C 1953.

Certainly is unusual and interesting to see in the flesh!
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Old 22nd Oct 2018, 5:09 pm   #9
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Default Re: Crazy Murphy 12" console V210C 1953.

Quote:
Originally Posted by McMurdo View Post
Blimey that's a bizarre chassis. I'd say The Man With The Pipe had something other than St Bruno in the bowl the day they came up with that.
Frank Murphy left the company with his pipe in 1937, so had no input on this design.
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Old 22nd Oct 2018, 6:18 pm   #10
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Default Re: Crazy Murphy 12" console V210C 1953.

I don't think Frank Murphy had much to do with the actual design of his receivers. The pre war oddness continued through to 1962 when Bush and Murphy combined. All the more fun for us!
By then the design of all makers receivers had become very mundane. J.
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Old 22nd Oct 2018, 10:34 pm   #11
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Default Re: Crazy Murphy 12" console V210C 1953.

In the model V210 Murphy got away with using a general purpose double-triode type 20L1 as the frame oscillator and output valve. The output section was supplied from the boosted HT.

DFWB.
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Old 23rd Oct 2018, 8:41 am   #12
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Default Re: Crazy Murphy 12" console V210C 1953.

Quote:
Originally Posted by Heatercathodeshort View Post
This range of Murphy chassis is without doubt the most bizzar ever produced. It was known as the 'Aeroplane Chassis' due to it's similarity in appearance to the aircraft rotary piston engine known as the Merlin...
I was sure that the Rolls Royce Merlin was a supercharged V12?

I do recall a radial piston engine of the time and I thought it was american? I'm not sure.

Bizarre looking set that Murphy, I rather like it's quirkiness
though and the way that they have designed it around a centre point rather than flat vertical/horizontal chassis.

Did it need much to coax it back into life?
The tube looks ok in the picture, what's it like to the naked eye?

Cheers
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Old 23rd Oct 2018, 9:48 am   #13
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Default Re: Crazy Murphy 12" console V210C 1953.

Rotaries were in 'the first lot'. I can't bring one to mind from '39-45.
What does the Murphy cabinet look like? Is it round, too?
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Old 23rd Oct 2018, 11:53 am   #14
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Default Re: Crazy Murphy 12" console V210C 1953.

Rather like this...
https://www.radiomuseum.org/r/murphy...ver_v210c.html
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Old 23rd Oct 2018, 7:22 pm   #15
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Default Re: Crazy Murphy 12" console V210C 1953.

Before I post the final details of the V210C I thought you might like to see these scans from the release of the V210 series, Murphy News, March 1953.
John.
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Old 23rd Oct 2018, 7:27 pm   #16
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Default Re: Crazy Murphy 12" console V210C 1953.

The remaining five pictures from the M.N.
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Old 23rd Oct 2018, 10:02 pm   #17
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Default Re: Crazy Murphy 12" console V210C 1953.

Does your set have the fringe area caps snipped out John?

Peter
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Old 24th Oct 2018, 8:40 am   #18
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Default Re: Crazy Murphy 12" console V210C 1953.

We must be telepathic. That is exactly what I am about to check later! Regards, John.
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Old 24th Oct 2018, 9:00 am   #19
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Default Re: Crazy Murphy 12" console V210C 1953.

It would be interesting to see what what difference there is in picture resolution and in RF gain.

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Old 24th Oct 2018, 5:13 pm   #20
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Default Re: Crazy Murphy 12" console V210C 1953.

It was time to feed it some juice, the first time for probably over 50 years. The metal rectifier appeared to be the original but looked clean and tidy. I searched for the mains filter but could not find one. A look at the makers manual does not show one but both poles of the mains pass through a double wound input filter choke.

So far so good.

Interlace looked a little worried as I fitted a 5amp 2pin Clix plug to the scruffy ends of the mains lead. As the plug approached the mains socket he ran from the workshop with his fingers in his ears. He did not return for at least an hour.

To be honest I didn't blame him as it's very unusual to find a television chassis that does not have one fitted. Interlace has been caught out before as a couple have exploded very close to his seat at the end of the bench. Now it is impossible for him to settle down until the offending item has been clipped out of service and handed to him to prove it's elimination.

With Interlace out of the way I plugged in this odd chassis and flicked the mains switch. The valves began to light with no pops or flames. There was 240V on the DC side of the rectifier but a screwdriver arc test on the anodes of both the 20P1 and U25 showed nothing.

I disconnected the U25 anode as a short in this valve would have damped the entire line output stage. [It is self oscillating in the V210C] The 20P1 valves very rarely fail but I have had a couple of U281's fail and therefore quickly tried a NOS replacement. Still nothing!

The boost capacitor was the next suspect, a 16uf 500V TCC can type electrolytic, dated FEB 1953. It was very leaky. With the first 500V electrolytic that came to hand clipped into circuit, the line timebase sprung into life.

The Paxolin connecting ring mounted just above the transformer top was a mass of corona. I switched off to examine it to find it covered in soot and general muck. This was cleaned off and dried.

Switching on again showed that all the protests had been calmed. There was a healthy spark at the U25 anode but it was not heating, so this had to be investigated. My thoughts drifted towards a faulty heater winding on the LOPT but the lack of a glow proved to have a simple reason. One of the U25 heater wires had rotted at the point it left the glass pinch and it was a simple matter to fit a NOS KY50/U25.

At last there was a screen illumination, not bright but a start. As usual the frame timebase was suffering from capityitis requiring the replacement of a few waxies in the oscillator and output stages.

A single valve and output stage is employed utilizing a B8A based double triode 20L1. To use Murphy's words 'The circuit is basically an unsymmetrical multivibrator, one half of which provides the scanning current to the frame output transformer'. What they don't tell you is the fact that the large frame output transformer is insulated from the chassis by rubber grommets and has its body connected to the 375V boost rail. I shake my head, honest.

With the coupling and feedback caps replaced a respectable raster was obtained but far from perfect. The raster lacked height and suffered from a top cramp, a symptom that usually points to over biasing of the output valve.

After checking the decoupling cap all seemed to be in order but a check on the 10K resistor, R102 Murphy service data, part of the cathode bias network proved that this had risen to 18K.

Replacing it got rid of the top cramp but it was far from linear with the height control on full. It took me quite a while hunting to find a test 20L1. I discovered two second hand ones but they were very low emission and useless. Just as I was about to give up I came across liquid gold, yes a NOS 20L1!

This improved matters considerably and with careful adjustment of the linearity and height controls was presented with a decent raster.

It was time to apply a signal but with the bench RF system connected the results were zero.
Not even a hiss or slight disturbance on the screen. I have been caught by this one before and gave it the full output from my Advance E2. At around 60mc/s the screen burst into life.

You have guessed it.. The set was fitted with a Sutton Coldfield RF unit and was tuned to channel 4. I keep an Aurora permanently tuned to channel 4 on the back of the Murphy V114, a receiver I wrote about a while back now. I feel that constant operation of the tiny channel switch may create an intermittent connection within the Aurora and therefore decided to obtain a second unit and leave this permanently tuned to the Birmingham transmitter frequency.

With this connected and a few adjustments made, a reasonable and just about watchable picture was obtained. The CRM121A was showing it's age and moving the heater tapping to the 20% setting only improved matters slightly. The focus adjustments, both permanent magnet and electromagnetic had to be set to their extremes to obtain reasonable focus. Good focus could only be improved by connecting a 47ohm resistor across the focus coil, to reduce it's flux.

The gain and contrast controls required their maximum settings. Valve base cleaning did little to improve the gain and I began to do what a man has to do. The RF unit and IF strip was cluttered with .001 .003 and .01uf capacitors that look like resistors. [You know the sort]

What a fiddle..........................AGHHH!

With these replaced the gain shot up allowing the sensitivity control to be backed off. This improved the picture but I know these Murphy receivers are capable of excellent pictures spoiled in this case by a picture tube that was well past it's best.

It was time to enter the inner sanctum above the garage, gloomy, mice droppings, spooky reflections and crunchy sounds underfoot, and that is in daytime! I discovered a tatty box labelled 'Mazda CRM123. 85% emission'. Yer, I believe that one and to add to my suspicions, it had a milky getter.

Oh well I'll give it a try I thought and moved the box towards the open hatch. I lowered it down to rest it on the roof of my old Land Rover and just as I was about to lower the hatch, there was a heck of a noise in the loft. The hatch was pulled upwards and to my total shock, Interlace in a panic fled from the loft wearing a battered bowler hat. I thought I had gone mad..Don't ask me where it came from. later it took a struggle to get Interlace to give up his prize and on examination of the insanitary hat discovered the words 'Dunn and Company' within the silk lining. We will never know.

The picture shows the test card with the very low emission CRM121A. The camera does flatter it a little. The CRM121A does not have a grey glass face plate requiring an optional external glass or plastic film filter. It was obsolete by 1952 replaced with the CRM121B with the filter screen.

This was replaced with the aluminised CRM123, the correct tube for the V210. It must have been fitted with a second hand tube at some point.

Part three will be the final notes that required just a bit of work to bring it to a satisfactory conclusion John.
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