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Old 31st Jul 2006, 10:55 pm   #1
FERNSEH
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Default Ekco TMB272 restoration.

I started on this 1956 mains-battery set on Sunday evening. As I do not have the correct main connector I simply wired the mains lead direct to the chassis mounted 18 pin plug. Also, a number of wire links for mains operation are required See pictures 1 and 2.

After some time I managed to get some results, pic 3. Later all the capacitors in the frame timebase were replaced and the raster can be seen on pic 4. Still pictures on the screen though. Two Hunts .003mfd capacitors in the vision IF stage were found to be faulty, after replacements were fitted some signal activity can be observed, pic5.

The plan is to get this set by Wednesday evening.

DFWB
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Old 1st Aug 2006, 9:50 am   #2
beery
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Default Re: Ekco TMB272.

Hi Fernseh,
The tubes on these always seem to be good.
I would point you in the direction of the warning of circuit differences between the set and the red book in the frame stage that I gave to Jeffrey this morning in the TMB272 Trader sheet thread.

Cheers
Andy
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Old 1st Aug 2006, 12:41 pm   #3
Duke_Nukem
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Default Re: Ekco TMB272.

Quote:
The tubes on these always seem to be good
Presumably helped by being an "occasional" sets ?

The only one I have seen working really did have give an excellent picture.

BTW, being Ekco, does this set use Visconol thing on the EHT ?

TTFN,
Jon
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Old 1st Aug 2006, 1:06 pm   #4
beery
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Default Re: Ekco TMB272.

Er yes it does use a Visconol.
The TMB272 produces 9KV with enough grunt to make the cap explode if it goes short.
This happened in my set whilst it was working with the cover off, my clothes got sprayed. Having had it happen to me I would not recommend operating one with the original cap in circuit, after all the oil is nasty stuff.

Cheers
Andy
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Old 2nd Aug 2006, 11:51 pm   #5
FERNSEH
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Default Re: Ekco TMB272.

The restoration of the TMB272 was completed on Wednesday evening.
This set employs a gated vision AGC system which is very similar to the TC209 and TC268 17" and 21" models.
It was in the AGC system where I was experiencing problems. On switch on the contrast control would operate normally, but after five minutes the picture would become over contrasted and in time the contrast contrast control became uneffective.
In this set the hot end of the contrast control is supplied from the boosted HT, so is the brightness control.
To keep this essay short, the problem turned out to be a leaky 0.1mfd AGC decoupling capacitor in the tuner unit. Ater replacing the capacitor in the tuner the contrast control operates correctly
The set now performs very well indeed. The CRT displays a very bright picture.
I must thank Forum member MurphyV310 for the repair tip.

So the set was repaired just in time for the Wednesday evening deadline.

DFWB.
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Old 8th Aug 2006, 10:03 pm   #6
FERNSEH
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Default Re: Ekco TMB272.

Wilfrid has posted pictures of the TMB272 on the Radiofil Forum.

http://retro-forum.com/viewtopic.php?t=10526

I have another Ekco TMB272 to restore sometime in the near future.

DFWB
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