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Old 18th Jun 2011, 9:11 pm   #101
murphyv310
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Bloomin rare that Mike, no wonder most engineers turn to the bottle! Good fault and well found.
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Old 19th Jun 2011, 10:01 pm   #102
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Quote:
Originally Posted by murphyv310 View Post
Bloomin rare that Mike, no wonder most engineers turn to the bottle! Good fault and well found.
Thanks Trevor.

Well, I'm sure people are fed up to the back teeth (whatever that means) hearing about this Ekco, so really no responses or replies are expected from now on, but I thought I'd post this just in the way of an update...

Having replaced a few components (as previously mentioned) in the VHF tuner, we had some RF although it was pretty low gain and we also had some I.F. problems (soft picture, sound / chroma not matching the same tuning position as the video). After another fair bit of prodding and poking and measuring of this and that we came to the conclusion that the UHF tuner was actually very low gain. Having already replaced both valves with what I thought were brand new valves some time back we were a little reluctant to randomly change them again, but, having put 2 actually-new valves in brought up the gain immensely, enough in fact to tune in stations with no problem at all (except for the I.F. problems).

Replacing 2 10K resistors in the schmitt-trigger PAL switch circuit partly-cured a long-standing PAL switch issue, although the problem still creeps back after 20 minutes of the set being on, so some more work is needed there.

Anyway, for anyone still remotely interested, here are the latest photos of the set - The first one (Test Card F) on UHF, and the second one (Colour Bars) on Video-In.

Thanks all.

Kind regards.

From Mike.
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Old 19th Jun 2011, 10:29 pm   #103
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Keep it coming Mike, I'm following this with great interest

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Old 19th Jun 2011, 10:32 pm   #104
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi i dont think anyone would be sick of hearing about this set it is an important piece of british history and nice to see it working . I know i would have never got around to this as it was too dornting. i dont think most bw restorers would now just how complex that shassis is. well done and hope it gets going on the tuner soon. Danny
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Old 19th Jun 2011, 10:54 pm   #105
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Keep it coming my friend, I am amazed with this set to be honest!!!!
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Old 19th Jun 2011, 11:04 pm   #106
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

As others have said, keep it coming Mikey!, all interesting stuff!
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Old 19th Jun 2011, 11:39 pm   #107
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

I hope you are going to punish that 3.3 meg resistor for being such a b**** to find....Maybe a hammer/sidecutters or a vice to crush it in? ..hehe
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Old 26th Jun 2011, 1:39 pm   #108
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Back from Spain and catching up on the threads and saw how healthy this set is looking now. Great to see the signals side is now sorted, tsk! Pesky valves! I look forward to seeing it in the flesh soon.
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Old 26th Jun 2011, 4:25 pm   #109
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Not fed up at all. It's fascinating and would love to see it in the flesh!
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Old 6th May 2013, 5:09 pm   #110
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi everyone. It's Mike here again with another bit of an update regarding the old Ekco CT100M. All who are bored stiff with hearing about the old thing, please accept my apologies.

Things have moved on with the monster set a little bit over the bank holiday weekend. Whilst anyone sensible was out sunning themselves in the glorious weather, my mate Tone (who kindly came over to kick my arse and get the set fixed) and I sat in the dark hall downstairs and sorted out a few faults and got the set another step toward working properly.

One problem with the set was it's general lack of "punch" and fairly wishy-washy contrast. This turned out to be a combination of high-value resistors in the video amplifier and the video "bootstrap" circuit including a resistor in series with the contrast control, which never even crossed my mind to check! Regarding the "bootstrap", the video from the solid-state detector diode is fed to the grid of a PCL84, from which the cathode supplies signals to the video amp, the sync separator and the simple-PAL decoder whilst the anode feeds the AGC amp and supplies sync in opposite phase for noise-cancelling purposes.

One other problem was (and still is) the front-panel mounted contrast control (330K). Alas I do not have such a pot (picture shown below) as the knob is all part of the pot and I'm not sure of another set which uses similar pots. The pot has a duff section so the contrast is always "maximum" or "not quite good enough". (I don't suppose anyone recognises what the pot might also fit do they? I guess anything roughly near that value will be okay.)

We also sorted out the mechanics on the "Hopt" (brand) UHF tuner. The tuning was always terribly stiff, had loads of play, and the fine-tuner didn't work. Dismantling everything, cleaning it all up and loosening one of the pulleys (which was jammed up against the casing) sorted the problem out.

The decoder was given a good once-over with the scope and the Philips PM5519 to get it all spick-and-span and nicely aligned. There is still a problem with poor saturation levels, "delayed" chroma and a slight lack of B-Y but I'm confident they can all be sorted out next time. (The slight lack of chroma and the delay of the chrominance relative to the luminance may be more to do with the I.F. alignment than anything else, especially as it looks like the I.F.s have been twiddled by some previous owner, perhaps in an effort to overcome the VHF tuner fault from ages back.)

The line is intermittently still a bit jittery and the line hold control works in a strange way but, again, they can be for next time.

The next thing to do is to get the set taken down to Cambridgeshire to have the I.F. aligned by an expert before tackling the few remaining bits and bobs.

Thanks everyone.

Kind regards.

From Mike.
Some pictures attached, but better copies (and also some other shots of the chassis etc.) can be downloaded from here:
http://www.oldtechnology.net/misc/Ek...0M_Repairs.zip
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Old 6th May 2013, 5:19 pm   #111
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Bootiful!

Thanks for the update
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Old 6th May 2013, 6:02 pm   #112
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Same controls as the Ekco T368, i managed to remove the stubborn press clip thats holding the control together to allow proper cleaning. The wiper needed some adjustment to use a good area of track.
If you do break the center spigot when removing the clip its easy to repair by drilling and pinning with glue.

Amazing set, well done

Steve

Last edited by Freya; 6th May 2013 at 6:08 pm. Reason: spelling
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Old 7th May 2013, 10:20 am   #113
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Getting better and better Mike That test card leaves a lot to be desired though (Private joke )

They are also the same controls as used on the Ekco badged Pye 11U dual standard mono sets if that's any help...
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Old 7th May 2013, 2:04 pm   #114
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Thank you for the kind comments NTSCUser, Steve and Taz. (Bloddy cheek re the testcard Taz.)

And (without wishing to make the thread sound like an Oscar speech) my apologies (and thank yous again) to Dominic, Danny, Jarl, Red to Black, Glen, Bob and Taz again for the previous kind comments that for some reason I rudely missed the first time around.

It is nice to get bits and bobs working on the set even though it feels like the law of diminishing returns is in full swing. Looking at some of the photos I've posted of the set over the years, you'd hardly notice that much difference in any of them. I think the major difference now is that you can turn on the set and expect it to work (even with it's remaining quirks) without having to dive inside or underneath and fiddle with something.

Anyway, to be honest, I'm happy with no replies if people can just humour me by putting up with me posting the continuing sagas of the old monster whilst my pals and I manage to get stuff working on it (or not).

Thanks all.

From Mike.
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Old 7th May 2013, 3:16 pm   #115
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi Mike,
I'll have to bring out your set's great rival, the Pye 405 NTSC colour TV. It's still here in all it's glory. I must fire it up and see what happens. It hasn't been switched on for ages.
The cabinet got tidied up last summer.
DFWB.
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Old 7th May 2013, 4:17 pm   #116
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi David. Oh, the two sets are really not rivals - I think they'd be the best of pals given the chance. That set of yours is really something quite amazing and I'm not embarrassed to say that I'm quite jealous of it. Thanks David. Hopefully we'll all see you at the meetup very soon. Kind regards. From Mike. (On his phone with no carriage-return key.)
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Old 7th May 2013, 4:43 pm   #117
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi Mike,
The Pye has still got that frame linearity fault. I've tried just about everything except the scan coils. It's time to tough out this fault and fit those spare scan coils I have. The rest of the set is OK. Well, it can only get better so to speak.
The fact is both sets are rare beasts and your's actually was a 405 line set initially. The Ekco is the much better looking set.
DFWB.
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Old 7th May 2013, 5:57 pm   #118
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Quote:
Originally Posted by FERNSEH View Post
Hi Mike,
The Pye has still got that frame linearity fault.
DFWB.
Hope im not teaching you to suck eggs, and i have not seen details of fault but have you tried isolatating the linearity control from the chassis (if its mounted on it); i had a similar problem on a Pye VT4 which was breaking down to the linearity pot housing, tested fine out of circuit.

Steve
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Old 7th May 2013, 6:23 pm   #119
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi Steve,
The frame timebase resembles that of the VT17 Luxury17 series of receivers. I'm sure that everything in the frame linearity circuit has been tested but I'm willing to go over the service procedures again before a set of replacement scan coils are tried.
The CRT and it's scanning components were sourced from the USA.

DFWB.
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Old 8th May 2013, 12:37 am   #120
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Nice work Mike that test card does look good. Can't wait for the next installment.
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