Murphy V530 repair.

[murphyv310]

Yesterday was the state visit from Geordie land of "Fernseh" you know that telly man from near Sunderland
Anyway to keep in with the Scots David brought up a Murphy V530 that actually came from System A ( Thanks Gary )
The set is quite tidy with just a little scratch on the cabinet and some deteriation of the rubber mask.
We set about the set yesterday. The lopt has of couse been leaking but two faults were apperant no doubt the original problems. The U26 valve base was burned and the "S" correction cap had exploded, these items were replaced along with a down to air 30P4. The mains filter cap was snipped and the set wound up on the variac, it was apperant that there was no line drive tihs was traced to R151 o/c & C121 s/c these were replaced and line came up.
The U26 was flashing so was replaced, we eventually got a weak raster but the Dag was sparking and there was also a mysterious sparking that could not be seen, I thought it was an internal arc in the tube but David thought it was inside the lopt. David was right and the lopt took half a mug full of Tesco's finest veggie oil, this stopped the arcing. We replaced some wax caps in the frame and sound stages and eventually got a nice picture, there were some issues with the scan coils that looked like a possible shorted turn but that seems to clear on its own.

I still need to do some more and also check some resistors as the line hold was one ended caused by R149 & R158 both being high, so I would suspect others would be the same.
Not bad though for an afternoons work.

[murphyv310]

Some more!

[murphyv310]

Last lot!

[audiomagpie]

Looks very clean inside. Cracking results too. Is this the same set as in your avatar?

Greg

[Heatercathodeshort]

That was far too easy..... John.

[FRANK.C]

Hi Trevor
Great result. It's very clean did you give it the pressure washer treatment.

Frank

[murphyv310]

Thanks guys.
It was quite easy I suppose John, it wasn't that clean there was a lot of oil around but it mostly came off with a cloth, I didn't use the pressure washer on this one Frank as it wasn't too bad.
The Murphy on my Avatar Greg is the V310, it has a 70 degree tube and is quite deep, the V530 here is a 114 degree CME1905 with the short neck, the whole set is very slim, it's not a brilliant layout and I would suspect they suffered with some cooling problems.

[HamishBoxer]

Looks excellent again Trevor,trying to think do i have a new crt for this in stock.

Cheers David

[murphyv310]

Thanks David.
The tube in this one is very hard, and for sure it's the original! Odd to get a 51 year old Mazda CME1705 so good, and as you know I have an NOS one in the Ekco to compare it with

[Tazman1966]

Nice set Trevor. What's accessibilty like? Do you have to remove the CRT to replace components?

[murphyv310]

Indeed you need to remove the tube, it is so easy though, all you do is remove the CRT base and EHT cap then loosen two big wing type nuts on the sides of the chassis and lift it away from the tube and mask, even the scan coils come with the chassis, takes all of 30 secs.

[murphyv310]

From the first picture you can see the mask was past its best.
I decided to remove it today. Oh dear what a job, it was all goooey and in a bad state. It took some time to remove it from the faceplate and Bakelite surround. I then let it soak in water and lux flakes for a couple of hours. I trimmed off the lip that goes around the glass, after all was dry I gave it a few coats of grey spray primer which is a good match for the original colour and of course does not reflect. After cleaning the faceplate and Bakelite surround, I used thin foam on the edge of the surround, the foam I used was double sided sticky stuff and the glass was carefully offered up. As I had cut the rotten lip off the surround I then glued it in place with hot melt.
After all this was done a quick dust was done ( I had cleaned everything first) and the mask assy was offered up to the tube and chassis, after doing up the bolts I used 3 long cable ties around the rubber surround to hold it tight against the CRT, the result is near perfect with the puckering on the mask all but gone.
I gave the cabinet a good waxing and lightly touched in the scratches, so the set now looks in nearly new condition. Just the remaning caps to be done.

[FERNSEH]

Hi Trevor,
The quality of the metalwork of Murphy television sets is of the highest, I'd say better than any other TV manufacturer. One just has to look at those metal pressings used in Murphy TV receivers from the 1955 models to the final Welwyn Garden sets such as the V759 series that were made in 1962.
The reality is that those Murphy TV sets cost too much to make.

The following Murphy branded Bush receivers don't compare.

Good news about the CRT mask, you have saved it just in time. In a few years time the thing would have become nothing more than a load of goo.

So which is the best of the Murphy sound mirror lid sets? Is it the V310, the rare V410 or the 110 degree CRT V510 series. My opinion is that they are all good.

DFWB.

[murphyv310]

David.
That is a very had question to raise! For me the "barrel Murphy's" made a lasting impression. The very first set I worked on as an apprentice was the V310 with all the engineers having a laugh at me trying to get the "back off"! There were still a few around in 1970. The V410 was still out on rental then for the pensioners at 10 bob a week and the "ol yins" loved them and so did I, they gave superb pictures and once you got used to the faults they could be repaired in no time.
The V510 were also still common but tube troubles saw them off, by the time I left British Relay in December 1974 they were all but gone!
I think out of them all the V310 has lasted longest due probably to a larger air space in the cabinet and better cooling.
I am sure that Murphy would have lasted longer had they paid less detail to the over engineered chassis in the V280/300, the V310/320 & V410/V420, The V510 series although wonderful does show some cheapness, perhaps the writing was on the wall!
Any one got a V410 or derivative?

[FERNSEH]

Originally Posted by murphyv310

Any one got a V410 or derivative?

Hi Trevor,
I'd certainly would like one for my TV collection.

Did the V410 employ the 90 degree electrostatic focus Mazda CME1702 CRT? This was Mazda's answer to the AW43-80. Mazda did make a magnetic focus 90 degree CRT type CME173. No doubt about it. Murphy did over engineer the chassis construction of their TV receivers. The fact is the companies' sets would have been just as reliable with normal construction methods. Anyway can we think of any other make of TV receiver that one would ever discuss the chassis construction?

Regards,
David.

[flyingtech55]

Hi Trevor

Is that a Hameg 'scope I see in the background? What happened to my Tektronix?

Tim

[murphyv310]

Hi Tim.
Your Tek is safe and sound, and less likely to be damaged while I am poking around line o/p stages with my old Hitachi!

[murphyv310]

Hi.
I have tried the set on radio and boy does that 441 ohm dropper get hot, no wonder the U26 base melted! I have fitted a 4.47uf cap in place of the dropper (400vac rated X type) and a 400 ma fuse in the radio heater supply and I now have a really cool running Radio.
I will need to replace the scan coils though due to trapezium distortion.

[murphyv310]

From My calcs the 441 ohm resistor should be repalced by a 7.2uf dropper but the heaters are normal with the 4.47uf cap. Any ideas where I am going wrong?

[FRANK.C]

Hi Trevor
Assuming that your replacing a 441R dropper that is supplying 0.3 A to the heaters.
I put the numbers into Paul's Dropper Calculations spreadsheet. And it worked out at 4.57 uF in series with a 33R 3 Watt surge limiter.

Frank