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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 24th May 2019, 3:03 pm   #21
greg_simons
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Default Re: Thorn 2000.

one more pic
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Old 24th May 2019, 4:00 pm   #22
dazzlevision
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Default Re: Thorn 2000.

Hello Greg,

I'd certainly replace the three vertically mounted"Dubilier" yellow/blue coloured capacitors on the convergence board - almost certainly leaky (in the CRT screen grid feeds).

As you may well know, the A1 switches tended to develop electrical leakage across their Paxolin base.
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Old 24th May 2019, 4:11 pm   #23
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Default Re: Thorn 2000.

Hi dazzle,
Yes indeed those caps are history, must admit I'd forgotten about the A1 switches, they'll be examined very carefully.
Greg.
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Old 27th May 2019, 10:17 pm   #24
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Default Re: Thorn 2000.

Quote:
Originally Posted by dazzlevision View Post
As you may well know, the A1 switches tended to develop electrical leakage across their Paxolin base.
Hi.

This was also very common on the 3500 chassis as well.

Regards,
Symon
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Old 31st May 2019, 10:15 pm   #25
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Default Re: Thorn 2000.

Hi Greg,
Those boards look good:- I guess you've had to put in a lot of effort to get them to that stage! The convergence board looks a bit charred, but hopefully it will work OK and hasn't become too conductive!

At least you have several EHT modules which is handy. Those heatsinks on the line output transistors seem rather undersized and indeed, mine run hotter than I would like. They have included heatsinks for the pair of jellypots though which is something I've not seen on any other set.

If it would be of any help, I would be happy to use my set as a test jig to test any or all of your boards once you have refurbished them. I think you did ask when you first started the thread.

One thing that did occur to me, was this the only solid state set produced that was capable of receiving 405 line pictures?

Could you post a picture of your power board (the one with the three big cans), especially the tag strip? It's the only board in the manual that doesn't show a layout and I need to see how the components should be arranged on the tag strip!

Well done on progress so far.

All the best
Nick
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Old 1st Jun 2019, 12:22 am   #26
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Hi Greg,
Those boards look good:- I guess you've had to put in a lot of effort to get them to that stage! The convergence board looks a bit charred, but hopefully it will work OK and hasn't become too conductive!

At least you have several EHT modules which is handy. Those heatsinks on the line output transistors seem rather undersized and indeed, mine run hotter than I would like. They have included heatsinks for the pair of jellypots though which is something I've not seen on any other set.

If it would be of any help, I would be happy to use my set as a test jig to test any or all of your boards once you have refurbished them. I think you did ask when you first started the thread.

One thing that did occur to me, was this the only solid state set produced that was capable of receiving 405 line pictures?

Could you post a picture of your power board (the one with the three big cans), especially the tag strip? It's the only board in the manual that doesn't show a layout and I need to see how the components should be arranged on the tag strip!

Well done on progress so far.

All the best
Nick
Hi nick
No problem, I'll get some pics on here tomorrow, yes indeed those boards have taken much time and effort, it would be great if you could test one or two items when I'm sure they're completely debugged.
Good news today, might have found a cabinet maker to reconstruct the wreaked cab and stand, I'll let you know how that works out and the cost,,,,,
The convergence board had an ancient bodge in the form of a wrong value replacement pot, which resulted in not only it's own destruction but a s/c static clamp diode and two other burnt out pots. All fixed now.
Quite lucky in having a total of five viable eht generator boards, I think there will be some freebies when it's all done.
Greg.
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Old 1st Jun 2019, 9:43 am   #27
HamishBoxer
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Default Re: Thorn 2000.

And do not forget those caps after the A1 switches go short too.(A1 Decoupling)
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Old 1st Jun 2019, 12:57 pm   #28
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Default Re: Thorn 2000.

hi nick
here's those pics as requested, if you need more let me know.
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Old 1st Jun 2019, 11:13 pm   #29
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Default Re: Thorn 2000.

Many thanks for that, Greg.

So VT2 does just dangle on it's legs from the tag board with a 'top hat' on! I thought that was one of my bodges from my youth!

Where does the 68V Zener (W15) mount officially? My version, while it works fine, is certainly not official!

Your PCB looks in rather better order than mine:- Mine has a big burnt area under the three 80 Ohm resistors with half the tracks missing!

Just a thought, I trust you are planning to make your set fully functional on 405 lines?

All the best
Nick

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Old 1st Jun 2019, 11:39 pm   #30
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Default Re: Thorn 2000.

Five posts moved to a new thread: https://www.vintage-radio.net/forum/...17#post1149517
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Old 2nd Jun 2019, 1:01 pm   #31
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Default Re: Thorn 2000.

Hi nick
Yes indeed 405 line operation is certainly not ruled out although I might have to ask some kind person here for the loan of a pattern generator or standards converter.
I have another rather less serviceable PSU here in need of restoration which you're welcome to for the postage, it does at least have a good board.
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