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Old 14th Jan 2009, 3:41 pm   #41
brunel
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

"I've ordered a new ECH84 sync separator valve."

Either you are too quick.. or I'm too slow on this, I have 3 new ECH84's that you can have.


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Old 14th Jan 2009, 5:21 pm   #42
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Quote:
Originally Posted by dominicbeesley View Post
Firstly let me say how unspeakably jealous I am and how much I am following this with interest! Looks like it will be a lovel set when its going properly

Secondly does anybody have a circuit online for this one?

Keep us posted!

Cheers

Dom
Hi Dom.

You don't have to be jealous of this old monster - You're welcome to come and play with it or borrow it whenever you like. You can even come and fix it for me if you like. It's there for people to enjoy, I'm just its custodian at the moment.

I certainly will keep you posted though.

Thanks Dom.

Kind regards.

From Mike.
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Old 14th Jan 2009, 6:48 pm   #43
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Quote:
Originally Posted by brunel View Post
"I've ordered a new ECH84 sync separator valve."

Either you are too quick.. or I'm too slow on this, I have 3 new ECH84's that you can have.


Thanks for the kind offer Brunel - If the valve never makes it here, I'll give you a buzz.
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Old 14th Jan 2009, 7:03 pm   #44
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi Mike, Glad to see a picture on the old girl. The CRT looks good from the pics too!

I'm playing with my G25K502 at the mo so when your done you can come and fix my decoder faults too!

Keep at it and good luck with the rest of the set mate, she's a beauty!


Cheers
Lee
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Old 14th Jan 2009, 9:09 pm   #45
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Quote:
Originally Posted by Hunts smoothing bomb View Post
Hi Mike, Glad to see a picture on the old girl. The CRT looks good from the pics too!
Hi Lee.

The tube is pretty good considering its age - These AX53-14 (RCA 21FBP22 equivalent) tubes were never hugely bright, but certainly they gave a very watchable picture.

Quote:
Originally Posted by Hunts smoothing bomb
I'm playing with my G25K502 at the mo so when your done you can come and fix my decoder faults too!
I hope you get the old '502 working again soon - The pictures on it that Brian showed me a while back were quite spectacular. Hmm, when I said I loved decoder faults that didn't mean to imply that I had any skill in fixing them...

Thanks Lee.

Kind regards.

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Old 23rd Jan 2009, 10:34 pm   #46
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Well, it's 1 step forward and 2 steps back I'm afraid.

My original thought that the ECH84 sync separator valve was faulty was incorrect - I replaced it with a brand new one and the large 50Hz hum is still on the control grid of the valve (when the valve is momentarily disconnected the hum on the control grid pin goes away, and I confidently expected a short to the heater somehow). Also on unplugging the 4.43MHz chroma amp valve (V18), the ceramic valve holder crumbled into a thousand pieces rendering the set unusable until I replace that. I don't suppose anyone has a ceramic B9A valve holder with a metal base with 2 mounting holes and a shroud for a valve shield? I'll put an ad in the Wanted section too. I would take a photo of the valve base but I left my camera at work.

Thanks everyone.

Kind regards.

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Old 24th Jan 2009, 1:39 am   #47
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

If it's on the grid, then it's on the input. Please don't pull valves and measure the pins when it's not in the socket - proves nowt.

A lot of sets (apart from very early 405 sets) generate their own 50hz signal by the way, so your 50Hz could be coming from there. If it's only there when a valve is pulled then ignore it. Do some capacitor changing and look around both the Line and Frame oscillator stages and the video and sync stages.

Cheers,

Steve P.
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Old 24th Jan 2009, 10:03 am   #48
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi Steve.

Quote:
Originally Posted by Steve P
A lot of sets (apart from very early 405 sets) generate their own 50hz signal by the way, so your 50Hz could be coming from there.
The 50Hz ripple that I am seeing is not in phase with the video signal and so I can only assume that it is coming from the mains supply somewhere. The 2 HT supplies are rock-steady, the only non-signal-related 50Hz round the sync separator is from the heater supply to the ECH84. My test of removing the valve momentarily was to disconnect the control grid of the "H" part of the ECH84 to see whether there may have been an inter-electrode short - The Nasty 50Hz sine wave disappeared to leave nice healthy looking sync pulses on the socket. (In this instance removing the series-fed-heater valve was a case of don't do as I do, do as I say, and I was quite prepared for the consequences of my slightly dubious servicing method.)

Thanks for the suggestions Steve - I'll still keep plugging away at it when I get a bit of time (and a new valve base).

Thanks everyone.

Kind regards.

From Mike.
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Old 24th Jan 2009, 10:07 am   #49
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

The 6.3v is AC, I presume.

If it's like the 1500, it will be DC though, so there may be a diode and a few caps in the 6.3v line....

Cheers,

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Old 30th Jan 2009, 9:46 pm   #50
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi everyone.

I thought someone might like to see a picture of the valve-base after I turned the TV upside down and all the bits of ceramic fell to the bottom (top) of the set. Also, here's a link to the schematic in case anyone is interested.

Thanks everyone.

Kind regards.

From Mike.

http://www.oldtechnology.net/misc/ek...0schematic.jpg
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Old 31st Jan 2009, 9:15 am   #51
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Crikey!

There's cracking, and there's completely disintegrating!

Trev
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Old 31st Jan 2009, 9:10 pm   #52
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Quote:
Originally Posted by trickytrev View Post
There's cracking, and there's completely disintegrating!
It is quite something, Trev.

A mate of mine came round the other evening and helped me change the valve-base as I'm kind-of "mentally clumsy" when it comes to trying to do stuff like that. He made a cracking job of it, and it meant that I could get back to trying to sort out the other faults.

To that end, the cause of my intermittent hum-bar on the video turned out to be a heater-cathode short on one of the 12BH7 valves (V14 on the diagram) which acts as the voltage stabiliser for the colour-difference outputs. To prove a point, I swapped it with the other 12BH7 and the hum-bar disappeared but the green was all over the place. So... I've put an ad in the "Wanted" section for a 12BH7 valve.

Thanks Trev and everyone.

Kind regards.

From Mike.
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Old 31st Jan 2009, 10:35 pm   #53
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hello Mike,

I'll put a 12BH7 in the post to you on Monday morning - no charge.

Kind regards,

Dave
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Old 1st Feb 2009, 9:51 am   #54
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Crikey - That's fantastic. Thanks Dave - That is most kind of you.
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Old 4th Feb 2009, 10:17 pm   #55
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

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Originally Posted by Framer Dave View Post
Hello Mike,

I'll put a 12BH7 in the post to you on Monday morning - no charge.

Kind regards,

Dave
Your valve arrived this morning Dave, and fitting it completely cured the enormous hum in the video. Thank you very much - That was extremely kind of you, and it was very much appreciated.

Also, yet another valve, this time an ECC82 in the line oscillator, cured the very poor line lock and brought up a pretty good well-locked picture.

All I need to sort out now are the other faults including no signals when switched to RF, slight frame linearity and shift problems, fluctuating brightness, poor EHT regulation, focus control at one end, occasionaly-flickering line, and lastly, the lack of colour.

I think there's enough there to keep me going for a good while.

Thanks Dave and everyone.

Kind regards.

From Mike.
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Old 4th Feb 2009, 10:23 pm   #56
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

That sounds promising Mike. Has the hum completely disappeared?
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Old 4th Feb 2009, 10:28 pm   #57
Mikey405
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

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That sounds promising Mike. Has the hum completely disappeared?
There is no hum on the picture at all now Tas, although I can still detect a slight 50Hz ripple on the sync in the sync-separator; also the sound has a hum on it, but that may turn out to be the same thing. I hope.
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Old 7th Feb 2009, 11:15 pm   #58
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

After spending a day of chasing my tail, I'm still not very much further forward with the colour problem with this big Ekco and I'm now feeling a bit gloomy. The set is supposed to be PAL (factory converted from 625 NTSC), but some of the circuit is subtly different to the PAL diagram on the schematic that I have. I am working on the assumption that the set is correct, but it looks like it has had work previously in the oscillator and subcarrier regeneration circuit so I don't know whether it has been wired up incorrectly or not. It's the 4.43MHz regeneration circuit that is at fault, but I'm not finding it very easy trying to get to the bottom of subtle stuff like phase loops with no real manual or waveforms.

Of the few voltage / waveform readings shown on the PAL section of schematic, a lot of the readings are "mostly okay" but I'm not sure whether they're "okay enough" if you know what I mean. The few waveforms shown in the schematic all seem to be idealised versions too, so it's difficult to gague whether there is a problem in certain sections either.

Anyway, with the medium amount that I know about PAL decoders, I think I have been able to deduce pretty much what is going on - it's just the "fine details" that are driving me mad. I don't really know enough about valve technology to draw conclusions regarding what voltages should give what results on a "fine" level either. If only I'd payed more attention at college all those years ago. I'm sure I'll get to the bottom of it eventually (probably with some help from some of the kind and clever people on here). Normally I'm pretty reasonable at sorting out PAL decoder problems, but this one's being a bit of a toughee.

No responses required BTW - Just venting my minor frustration really.

Thanks everyone.

Kind regards.

From Mike.
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Old 7th Feb 2009, 11:26 pm   #59
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Get your scope out and check for waveforms. Is the 4.43 there, and are the outputs to the various phase loops LOOK OK and are at a sensible level.

You're going by trial and error here, and the chances are that if the set is a 'Test Set' so to speak, it may have been modified in it's life. Is the Chrominance getting in OK?

Sometimes having a type on a website means your brain has time to work it out.

Cheers,

Steve P.
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Old 8th Feb 2009, 11:04 am   #60
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Default Re: Ekco CT101 is alive (Actually a CT100(M))

Hi Mike.
Dont get gloomy! Try to find the colour killer circuit and disable it, the set as a "prototype" may not have one, usually turning up the chroma will confirm it or not, if there no colour noise at all or any colour info theres a good chance there is a killer.
Its well worth disabling it if you can, often seeing a fault on screen will put you right on the area plus a photo posted here will help.
You have said the set was 625 NTSC to start with with add ons for PAL, Can you try a 625 NTSC signal at all, do you have a pattern generator that will produce it, that may also be where to start just incase there is something wrong with the PAL mod.
Cheers
Trevor

PS the Colour Killer should be incorporated in the PAL section but there might be a form of colour killer in the NTSC part, Any chance of a scan of the diagram.?
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