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B&W TV GEC BT-2147, let the fun begin!

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Lloyd
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I picked up this little set from the recent RetroTech event, it’s one that’s been on my bucket list for many years! But they seem a little thin on the ground, certainly not as common as the good old Bush TV22. The chassis layout is similar to the Bush, with its double decker design, and it lives in a one piece Bakelite cabinet, but that’s pretty much where the similarities end.

Today I managed to lug the set into the workshop, and set about doing a few tests, mostly on the CRT, as these are notorious for being trouble, from heater to cathode shorts, disconnected cathode, or shorted heater, and this one is no exception, sadly! I started by testing around the tube base with the multimeter, checking continuity of the heater, and sure enough it has continuity! It measured 2 ohms… from what I’ve read this tube should have a 10.5V @ 300mA heater, which I’m sure should be a little more than 2 ohms! I connected it up to the bench power supply, and slowly wound it up, with the current limit set on 300mA I could just about get it to 3V, I didn’t want to push it too much and blow it open, so left it at that, it did begin to glow after a while, so I tried the Megger trick on the tube, but got nothing on screen, so it either wasn’t hot enough, or the tubes also low emission! I think for getting the set going I’m going to have to borrow a tube from something, probably the 385U again!

I did try to get some life from the chassis whilst I was at it, showed it some mains via a lamp limiter and the variac, the 100W bulb glowed a dull orange at 200V, and nothing else seemed to be happening in the set, I didn’t see any valves glowing, so next job is to check continuity of the heater chain. 

 
Posted : 09/06/2024 9:35 pm
LSmith and crustytv reacted
slidertogrid
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What a lovely set! I had a look on Radiomuseum. GEC certainly liked the Z77 ! I will follow with interest! I have my fingers crossed for you that the tube will be OK...

 
Posted : 09/06/2024 10:03 pm
Lloyd reacted
LSmith
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I really like the look of these - there was one at the BVWS Wootton Bassett auction in December which I was outbid on. I wonder if this is the same set that has been sold on to you?

I will follow your progress with interest too.

Laurence

 
Posted : 10/06/2024 8:21 pm
Lloyd reacted
Lloyd
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@lsmith

It probably is! Probably found the tube to be toast so passed it on! I should have spotted the fresh solder on the tube base when I was looking at it, but I just wanted the set, and went for it anyway!

B68682CD 0295 4E11 8EA0 434DD98A77D7

In that photo the focus magnet is not present, I do have it, I took it off to try testing the tube with the Megger.

I did some testing last night, the heater circuit is fine, I got some life from the set! The frame stage started up, firstly with some odd squeaking noises, then the usual rattling noise of a frame stage running too slow. No sound from the speaker, and no life from the line stage, I was still running through the 100W lamp limiter, which was glowing quite brightly.

 
Posted : 11/06/2024 9:16 am
LSmith and slidertogrid reacted
slidertogrid
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I hope if the set was purchased from a BVWS auction it wasn't sold on for a profit.... We all got a Bollocking (not a swear word, I checked 😀 ) about that in "The Bulletin" a few years ago after someone bought a Decca Decola and then sold it on for a profit. We were told that "we will investigate" any further breaches in the future... Some members were banned apparently... 🤐  

 
Posted : 11/06/2024 10:24 am
Lloyd reacted
Lloyd
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Oops! I’m sure the guy I got it from said it had been with him a while, and he had 3 of them!! 

 
Posted : 11/06/2024 12:26 pm
slidertogrid reacted
Cathovisor
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@slidertogrid

Re: "bollocking" - I would rather see that word used than the frequently substituted "rollicking", which has a completely different meaning.

 
Posted : 11/06/2024 2:48 pm
slidertogrid reacted
slidertogrid
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Posted by: @lloyd

Oops! I’m sure the guy I got it from said it had been with him a while, and he had 3 of them!! 

I'm sure that is true, to be honest my post was a little tongue in cheek. I won't comment further as I don't want to drag your thread off topic.. The only thing I wonder when people say they have a few of something is if the one they are selling has been the parts department for the others...Let's hope not.. ( I can be a cynical old Hector at times) 

 

 
Posted : 11/06/2024 4:40 pm
Cathovisor
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@slidertogrid What my colleague refers to as "a Christmas tree".

 
Posted : 11/06/2024 5:40 pm
slidertogrid
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@cathovisor Yes I bought a couple of radios from Harpenden years ago only to find the wrong chassis lobbed into a cabinet and the back firmly screwed on. The worst was a lovely PYE multi band portable that had had the main PCB chopped out and again the back screwed... I bit how I felt when I looked inside!  

 
Posted : 11/06/2024 5:57 pm
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