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Old 4th Nov 2015, 6:54 pm   #21
brianc
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Default Re: GEC 9 Inch TV

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Originally Posted by BassoonBloke View Post
does your power supply chassis have the EHT TX and if so, would you consider passing on to me for a price of your choosing (as long as it's not going to break the Bank!!).
I'm sorry, Alan. Only the other mains Xfmr is there. The EHT one was missing so sorry, I can't help.
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Old 5th Nov 2015, 9:36 am   #22
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Thumbs up Re: GEC 9 Inch TV

Hi Brian,

Thanks anyway,
It was worth a try.
Ed Dinning has offered to rewind the EHT winding if I wanted to give it a go, but I think i'll hold off for a bit.

Cheers,
Alan.
P.s. I think the 7094 looks a bit like a Dalek from Dr Who
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Old 5th Nov 2015, 7:21 pm   #23
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Default Re: GEC 9 Inch TV

You got a lovely TV there! I've always fancied one of these myself, but they very rarely come up for sale (or at least I never see them!), and the one that I did see a few years ago went for quite a bit! I like that it still has an old round pin plug on it too! Definitely not been used in a good long time.

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Lloyd.
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Old 7th Nov 2015, 5:50 pm   #24
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Default Re: GEC 9 Inch TV

Hello Lloyd

Thanks for the nice comment, this is certainly well built but just take a look at the cobwebs and dust, looks to me as if it has never been on the service bench. should I ever wish to part with it your be the first to know, but for now I have to work out how to best deal with getting it safely out the cabinet to renew the mains lead, I do not think that I wish to disturb it too much. If I can get a mains lead on it, I think the best option is to get it on a variac and wind the mains up very slowly.

Best wishes

Ken
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Old 7th Nov 2015, 7:06 pm   #25
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Default Re: GEC 9 Inch TV

That looks in remarkable condition, Ken. Very little, if any, signs of rust. This probably means that the wound components will be in good condition.
If you are going to wind it up on a variac, may I suggest that you disconnect the primary of the EHT transformer initially. Later, while you're working on the set's signal side, remove the EHT rectifier and insulate the top cap connector well - clamp it in a plastic box or something similar as you'll need the EHT transformer connected for the TV valve heaters. I'm sorry if you already know how to suck eggs but there's nothing like too much care with these TVs!
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Old 7th Nov 2015, 8:50 pm   #26
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Default Re: GEC 9 Inch TV

Many thanks Brian, I will do as you suggest, I read somewhere that it is advisable to remove the EHT rectifier when taking measurements but there is nothing like taking good advice from others like you who are well versed on the subject, like John said these are lethal sets to deal with inside. It will take a while to get the dust and cobwebs out.

Regards

Ken
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Old 8th Nov 2015, 12:53 pm   #27
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Default Re: GEC 9 Inch TV

Hello Ken,
If you are unable to repair this GEC BT7094, please offer it to another Forum member before passing it on as a theatre prop. John.
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Old 9th Nov 2015, 7:17 pm   #28
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Default Re: GEC 9 Inch TV

Hello John, I am not letting my GEC BT7092 go anywhere, I think you are getting a little muddled with another set I had. Now here are a couple more pictures of the GEC, I have now put a new mains lead on, the original was very perished, I also gave a little lubrication to the push button assembly and whilst at it I got a little more dust and cobwebs off the top of the chassis and gave the screen a wipe over. I am pleased to know that the set has not been tampered with in any way and to say the least everything looks original. I do not intend to disturb much in this as I think its best left alone. More to come on the progress.

Regards

Ken
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Old 10th Nov 2015, 1:51 pm   #29
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Default Re: GEC 9 Inch TV

Here's another couple of pictures of the louvre's at the front of the cabinet, one from inside of the right hand side which is the troublesome one and a front view of the left hand side to give some idea I am up against. Is there a way of making the individual bars to match that of the ones left in. Can some thin architrave be soaked and bent into the shape and some dowel in the same manner to form the particular pattern and shape. Perhaps one of the members is a cabinet maker.

Regards

Ken
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Old 10th Nov 2015, 6:11 pm   #30
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Default Re: GEC 9 Inch TV

It should be possible to remove one of the existing parts to make a mould from it and cast a replacement in resin or some other medium. They look as though only 3 screws hold them on! It sounds easy, doesn't it .
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Old 11th Nov 2015, 12:58 pm   #31
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Default Re: GEC 9 Inch TV

Hi Brian

Yes, does sound easy, I had thought of what you suggest, at least then if I have a mould I can re-produce them. Will see which is the best way.

Regard

Ken
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Old 14th Nov 2015, 3:30 pm   #32
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Default Re: GEC 9 Inch TV

Little more on the GEC, I removed all the valves one by one and as I did, I cleaned the base pins and put a little cleaner on each valve base, this helped solve the problem of the valves making connection in their bases. In the meantime I borrowed a variac and connected the set to it, starting at a low voltage of around 20V then gradually increasing as time went on, with the variac now at 150V the tube shows signs of life with a brief show of a spot then goes as the HT and EHT build. So looks like the set will spring back to life after all these years.

Regards

Ken
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Old 14th Nov 2015, 6:29 pm   #33
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Default Re: GEC 9 Inch TV

You're lucky that the transformers seem OK. Be careful though, of trapped moisture. Make sure they, especially the EHT one, have plenty of time to dry out just in case there is some moisture about. Perhaps leave the set on 100V for a couple of days - not unattended though!
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Old 14th Nov 2015, 8:24 pm   #34
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Default Re: GEC 9 Inch TV

Quote:
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Is there a way of making the individual bars to match that of the ones left in. Can some thin architrave be soaked and bent into the shape and some dowel in the same manner to form the particular pattern and shape. Perhaps one of the members is a cabinet maker.
I read these TV threads in awe, and have nothing to contribute - but in this case, I might have a go at routing one of these profiles.

On many routers you can unscrew the sheet of thin plastic they run on across the work piece, and replace with a larger piece of nylon or polycarb (or even thin ply) with a hole cut in it for the cutter to pass through. Then drill a hole somewhere in this sheet to pass a pivot pin / screw through, a distance of one radius from the axis of the cutter - where the radius is that of the curve you want to cut. Screw it lightly to the material to be cut through this hole, and spin the router around it, perhaps increasing the depth of cut a bit at a time in a few passes. Then cut out the sector of arc you need, and finish by hand / perhaps add the 'roll' at the bottom with a linisher?

Sounds a bit more complicated than it is. Whether you can find a cutter of the right-ish profile is I guess the only problem.

cheers
Mark
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Old 14th Nov 2015, 9:56 pm   #35
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Default Re: GEC 9 Inch TV

Cheers Brian for the info on moisture, after a little while the set had been powered up some of the electrolytic caps showed up to be worse for wear, so now got the task of finding suitable caps for the power supply section, they seem to be single value caps like 16uf 450V 8uf 500V 32uf 450V ect. Should keep me busy for a while.

Oh and thanks Mark for the wood work info

Best wishes

Ken
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Old 16th Nov 2015, 5:29 pm   #36
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Default Re: GEC 9 Inch TV

Here's a bit more on the progress of the GEC BT7092, I have replaced one of the electrolytic capacitors within the PSU, the 16uf which was starting to get jolly hot. There are two electrolytic caps shown as a dual one in the circuit, these are on the top side of the chassis, but are in a very awkward location (see pictures) got to work out how to best deal with them in order to replace. The circuit ref are C69 and C80 but appear as separate caps on the chassis.

Regards

Ken
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Old 16th Nov 2015, 6:57 pm   #37
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Smile Re: GEC 9 Inch TV

Good evening,
If the missing louvre is circular, they could be easily made on a wood lathe and then a segment could then me cut out to suit.
I expect a local woodworker could make that missing segment fairly easily with one removed as a pattern.

Christopher Capener
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Old 16th Nov 2015, 9:10 pm   #38
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Default Re: GEC 9 Inch TV

Hi Christopher

Thanks for the wood work suggestion, not got round to finally sorting the cabinet out though yet. Its the electrolytic caps I have got to sort out, I meant to add that although C69 and C80 appear as a double capacitor on the circuit and they appear to be shown as two together on the top side view of the schematic diagram but in reality there only seems to be one in the position shown on the schematic which adds confusion as to where the other one is or should be.

Regards

Ken
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Old 20th Nov 2015, 5:43 pm   #39
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Default Re: GEC 9 Inch TV

Sorted C69 and C80, this physically appeared as a single cap but it had a pos each end. replaced this and a couple more which are hidden below the chassis. Got plenty of EHT and HT now, but valves in it are on the low side of emission. Got to find some L63 valves and some Z77's and a X81. Not tried the radio yet.

Regards

Ken
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Old 22nd Nov 2015, 1:39 pm   #40
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Default Re: GEC 9 Inch TV

Hi folks

Got to the stage where there is flashes of interference on the screen when contrast control moved or when an aerial is pushed into one of the sockets but no actual raster, I switched the set to radio but no response from the radio side of the set. I checked most of the voltages around the set on the valve bases except EHT of course and these are similar to those listed in the service manual, I haven't as yet inserted a proper signal into the socket for the TV side and wonder if the screen remains blanked off until the set receives a signal, any thoughts

Regards

Ken
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