My 2021 project, Murphy TV but not sure of model?

[AdrianH]

This was a princely sum of 99 pence. I had the feeling it would end up as just being scrapped so did a drive to save it at the end of lockdown.

I am not sure what model it is. I initially thought it was a V250 going from pictures, the CRT is a 17 inch CRM171 (V240 14 inch).

But Now I have the TV Chassis at home I am not sure. There are differences between this chassis and what information I can find in the Trader sheets that suggest it is something different to Trader sheets 1262 and 1268, or 1308 V270(only 14 inch)?

The back panel controls would indicate a V270 style chassis, but it appears to have 4 more valves similar to the V240A, perhaps there was a 270A or other version that is not in the trader set of sheets?
A few pictures attached.

If anyone has the correct information I would be grateful to find out.

This is a next year project that will probably start with a good degrease and wash down before being dried in a cardboard box.

I was wondering if the LOPT is actually in oil, the area around it is particular grimy as though something jhas been spilled over it?

The only tests I have done to it so far is to ensure the heater meters something at 5 Ohm, and that t does not measure short to any other pins.

Adrian

[AdrianH]

I entered a few model numbers into Google for searching and it looks like it is a fringe model V280. It has the same valves as the one in pictures of this link.
https://www.radios-tv.co.uk/communit...s/murphy-v280/

Adrian

[Heatercathodeshort]

I don't want to dampen your enthusiasm but these Murphy receivers can be awkward to repair.

The line output transformer is certainly oil filled and can be a weak point. Even if the windings themselves are OK the oil is usually contaminated with moisture and can be difficult to extract, boil off the moisture and refill.

The Mazda CRM171 is a 'difficult' Mazda tube suffering from low emission and O/C cathodes.

It will require a truck load of caps to replace the paper tubulars and the small decouplers that look like resistors.

I would suggest you attempt to get the line output stage working. You can then gain some idea of the goodness of the LOPT and tube. The rest is just a laborious cap change. The valves themselves are very reliable.

In the 60's the trade tended to avoid Murphy TVs for overhaul and resale due to these expensive and at that time difficult to obtain spares. Murphy would not supply direct to non Murphy dealers with the result that you had to be 'nice' to your local Murphy dealer in the hope that he would order the bits for you and pay his surcharge.

It will certainly be interesting to see how your Murphy progresses. It's been a very long time since I had my fingers in the back of one. Good luck with it. John.

[AdrianH]

The Chassis will sit in the garage for a while, I was thinking of trying to test the CRT anyway I could, I have read about issues with it, all I was going to do initially with it is power up the heaters and apply a bit of volts between cathode and grid and measure current, sort of a rejuvenator test if you will, this in the hope it will let me know if the cathode is OK?

As to the rest that will depend on the tube before I move forward. Finding information is the first step.

Adrian

[line sync]

No mention is made of the cabinet , i assume it has not got one ?

Robin

[AdrianH]

Hello Robin, correct it does not have a cabinet, or Knobs for that matter. But at 99 pence worth a play with it.

I made a side of my Ferguson 991 cabinet and FERNSEH is making a more than functional cabinet for another 991. If I get it to work I am sure I can make some functional facsimile to keep it reasonably safe? But that is a long way off at this point.

Adrian

[FERNSEH]

If a cabinet from a V250 or V250C ever turns up it will house the V280 chassis. Mechanically almost identical except for a different range of valves.
Unlike most 17" CRTs which have 38mm necks the Mazda CRM171 CRT has a 35mm neck.

DFWB.

[AdrianH]

The cabinets seem to be more popular then the actual TV a Murphy cabinet for repurposing is out there for £95.

Adrian

[FERNSEH]

The Murphy V250C console TV set. The V280C is likely to be similar.
Easy cabinet to replicate.

DFWB.

[AdrianH]

I downloaded a brochure of the Murphy Range 1956 last night and it showed the table version, which is probably what I would go for.

I was wondering if they were the same cabinet size as the 14 inch models, as looking at the screens within the cabinet's the 14 inch has more surround? The control knobs seem to be in the same relative place.

Adrian

[AdrianH]

I have been searching without a lot of success for the circuits of the Murphy 280A. Yesterday I found on Ebay a local seller with 6 Volumes of radio and television servicing covering 1956 to 1962.

They are well used books and battered, but I think could be very handy as a reference for circuits. It does cover the 280A so I may have better chance with the chassis later.

Adrian

[1955APREN]

The new DVD- Roms at the top of page list's Murphy v280a as been available

[AdrianH]

I did not think £30 for 6 volumes bad?

Adrian

[Restoration73]

It's a typical price.

It's a bit annoying the circuit diagram is spread over 7 pages, but you will find it useful.

[peter_scott]

It's spread over just as many pages in R&TVS and there's no component layout.

Peter

[Ed_Dinning]

Hi Adrian, the red books are always a good buy if you like to handle a book. Paul's collection of circuits is certainly much more comprehensive and better indexed, but a good price for the books and I'm sure you will find them useful

Ed

[dave walsh]

Agreed that Paul Stenning has provided a truly amazing digital archive service for enthusiasts [at a very reasonable price] and long before the current, perhaps too detailed, interest in restoration. It may be around in the next Millenium Currently ,the various editions of the "red books" can still delight with unexpected content. I've got more than a few. Hard to get rid of, once you start reading!

Dave W