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B&W TV Murphy A640 Acoustic de-luxe rebuild

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Cathovisor
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@colourstar Well, if it is a rosewood example it'll look superb when restored. One of my favourite veneers, very fashionable 1935 - 1937 on radio sets as a relief to walnut (Zebrano was very popular at that time too). I think the Murphy A40C was veneered mainly in rosewood with Thuya Burr on the top panel.

 
Posted : 27/08/2023 9:10 pm
Reelman
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Our very first “bought” rather than gifted TV was the later single standard colour version. Came from a TV warehouse in Earlsdon, Coventry in 1982 and cost £40. The white paint was beginning to show its age by then so I veneered the case with teak and painted the front Matt black. Sacrilege today of course but at the time it looked pretty good. Also replaced the respectable 8x5” speaker by a Tandy 10x6” with integral tweeter. You can imagine what the huge magnet did to the picture so I also added a metal screen. 
When I showed my wife the picture at the start of the thread it jogged her memory, seems I melted the living room carpet with her iron used to apply the veneer!

Good luck with the restoration!

Peter

 
Posted : 06/09/2023 9:51 am
slidertogrid reacted
Linescan87
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20230908 135638

I recently picked up a shabby Acoustic de luxe. Cabinet is dated 15 September '67. It has several Granada labelled valves in it, did Granada rent them?

 
Posted : 11/09/2023 12:37 pm
slidertogrid
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It is quite surprising to me how many are still around.  I didn't see very many 'back in the day'. A few A823 colour ones but only a couple of A640 mono sets. And none were orange, white and a dull green were the colours that I remember. Oh, and the really rough teak one mentioned earlier that did end up orange... 

What is the set like inside, good condition? is the system switch linkage from the tuner to the chassis still there? I think it is a rod on this model ? Some other A640s were Bowden cable. It is missing on my set so a photo would be really helpful if your set still has it. It should be a good restoration project, will you respray the cabinet or repair just the damaged areas and blend in?

I don't know if Granada had any acoustic De luxe models, they did buy out other firms over the years so it may have come to them that way?  Usually Granada sets had a fairly large blue label on the back which was difficult to remove without leaving some trace, Is there any labels or remains on the back?

Rich

 
Posted : 11/09/2023 4:20 pm
Linescan87
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Hi Rich. 

No stickers that I can evidence of. The LOP valve are Granada but of course they could have been liberated..

The chassis it's is quite rough with signs of damp storage, cabinet is de-laminating badly and a little worm evidence too. 

The system switche is worked via a bowden cable on this one. The tube has also been replaced at some stage.

 
Posted : 12/09/2023 11:10 am
slidertogrid
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Posted by: @linescan87

Hi Rich. 

The system switche is worked via a bowden cable on this one. The tube has also been replaced at some stage.

That is interesting, when you get chance a picture would be very helpful.  Is the LOPT a plastic overwind or 'pitch'? If it's plastic there isn't a lot you can do but if it is pitch It would be a good idea to dry it out if the set has been damp. As mentioned on a thread on here.

I find 36V (three 12v PSUs in series) gets the winding nice and warm. I have successfully dried a few out using that method. I give them 2 or three days and on a couple of occasions a foamy white gunk has been expelled. Once from the middle of the overwind once from where the EHT rectifier Top cap lead comes out of the winding! 

If the set was owned by Granada when the tube was changed it would have one of their blue label tubes fitted. Maybe as you say it was just repaired by a Granada engineer doing a 'Private job'. Unusual for a LOPT to outlive the tube if it is the original pitch LOPT. 

I had another hour on my set yesterday, I now have it working on VHF the tuner switches were the problem. It works well on 405 and reasonable on 625 but the picture width and height are different between the two systems and the contrast is lower on 625. If the contrast is advanced too far on 625 the sync is lost and the picture goes streaky so there is still plenty to do.

I don't know if I can rig up a suitable Bowden cable but I would like to get it switching systems properly. You are fortunate that your set still has the cable most i have seen have been removed or at least disconnected, sometimes not very carefully! 

Good luck with your set! I will follow with interest! 

Rich.

 

 
Posted : 12/09/2023 12:01 pm
slidertogrid
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I am getting there with this set now. Just a few little bits to sort, the on/off/ volume control bracket to make and to connect up the system switch lever on the chassis to the tuner. Other than that it is pretty much done. Today I have replaced some more capacitors in the frame stage this has got the lin adjustment within the range of the controls, It really needs some replacement lin pots though they are all a little touchy as is the height pot and 625 line hold control.

On problem that did bug me was that the picture geometry was fine or at least pretty good at normal brightness and contrast settings but if I turned the brightness and contrast down the picture became distorted the distortion could be controlled by the brightness and contrast controls.

I wondered if the boost capacitor was the problem so I checked it on my tester and found it was miles out capacitance-wise, a sure sign it is leaky. A replacement sorted the problem. The line panel does still have a few original plastic capacitors but it seems to be OK with that.

I had to replace all of the capacitors on the IF panel though every one was dud and replacing them has cured the streaking at higher contrast levels and got the AGC working. The only capacitor on the IF that checked OK was the LT smoother so I left that.

The picture height is a little bit higher on 405 than 625 but i can set the height control so it is acceptable on both systems I am not too worried about that! 

So the 'Bitsa' lives. The Frankenmurphy!  It is made up of the cabinet, speaker and back from the original gutted set. The tube that came with that cabinet (which was loose and disconnected from the rimband earth wire) so I don't know if that was originally the tube from that set. Scancoils, Chassis, and IF panel from my spares set, Timebase panel, Tuner and speaker transformer from my spares and a set of new Push button knobs I had in stock. Valves from my box of 'pulls'. The LOPT was made up from a primary and core I found in a box of LOPTS I got from somewhere and an overwind from an A774 LOPT from the same box. Not very original but better as a telly than a pile of bits! 

First picture shows the distortion at low brightness. BBC2 is 625. Test card C is 405.

20230914 153638
20230914 152915

Picture three is after replacing the boost cap distortion cured. 

20230914 154600
20230914 152922
20230914 153020

 

 
Posted : 14/09/2023 3:54 pm
ntscuser and Lloyd reacted
Linescan87
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Hi again, 

Great progress there Rich. Mine is on suite a state, I only bought it because it was cheap and might yield a few parts if nothing else. We shall see. 

There is actually two bowden cables on this, one working the other.

20230914 171254

 

 
Posted : 15/09/2023 3:20 pm
slidertogrid
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Ah, I see, yes I suppose it was the only way to do it because of the acute angle. It wouldn't be possible to loop a cable round on itself it would be way too tight.  I haven't got the bracket that is mounted on the tuner either so I may have to leave it as it is.

Is your set really that bad? It may need a lot of work but orange ones must be rare and worth saving unless it is absolutely shot. The one My mate Mick did was dreadful cabinet wise but it looks good now. It is a shame the gutted one on facebook can't be bought cheaply your set would have all the parts to make one good one out of the two...

I have adapted the volume control bracket to fit my cabinet today. I am just hoping it will fit! 

 
Posted : 15/09/2023 4:32 pm
slidertogrid
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The set is now all together and looking good on its (borrowed, thanks Mick!) pedestal stand. For the time being it has displaced my Etronic radiogram that usually lives on the landing near my workshop door. 

20230917 190527
20230917 191043

The modified bracket enabled the On/Off/Volume control to be fitted, it was a bit of a struggle I had to remove the tuner,

move the chassis over and lay the set on its face on the bench. I had to trim the bracket down so it would fit the escutcheon then re drill the mounting holes and make up some spacers to stand the pot off a little so the knob was flush with the trim.

I have given the set a polish and touched up a couple of chips in the paint. That will do for now. it could really do with a couple of new lin pots and the line hold pre set (625) is still touchy despite stripping it and cleaning it. 

 

 
Posted : 17/09/2023 8:06 pm
ntscuser and Lloyd reacted
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