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Old 16th Jan 2023, 6:41 pm   #1
G8vsjDave
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Default Ferranti TC1004 (Ekco T311) spot suppression

Hi there folks, towards the end of Autumn, while the weather was still warm(ish), I stripped, cleaned and re-varnished the cabinet of my Ferranti TC1004 (EKCO T311). Today, I’ve been busy re-assembling the television and on testing I realised I still had a few things to sort out.
There doesn’t seem to any form of spot suppression on this model. On switch-off, I am left with a very bright spot that slowly fades out over about 30 seconds. Is this normal? I am currently running the set without the metrosil fitted, would fitting that make much difference?
Dave
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Old 16th Jan 2023, 6:51 pm   #2
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Default Re: Ferranti TC1004 (Ekco T311) spot suppression

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Originally Posted by G8vsjDave View Post
I am currently running the set without the metrosil fitted, would fitting that make much difference?
Dave
I believe so yes as it will discharge the EHT upon switch-off.
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Old 17th Jan 2023, 5:19 pm   #3
G8vsjDave
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Default Re: Ferranti TC1004 (Ekco T311) spot suppression

Thanks Andrew. The metrosil has been re-fitted and yes, it made a difference, but I still get a bright spot for a few seconds. I guess that’s normal and there is no provision on this model for spot suppression.
Dave
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Old 17th Jan 2023, 6:36 pm   #4
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Default Re: Ferranti TC1004 (Ekco T311) spot suppression

I think some dual standard PYE sets had a connection to the neutral on the power switch this provided spot suppression. I may be wrong as the memory is vague, in the case that the power was disconnected rather than the set switched off by the sets' own switch you would then get the switch off spot... I think...
Have you checked the diagram to see how suppression if any is provided?
Rich
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Old 17th Jan 2023, 7:27 pm   #5
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Default Re: Ferranti TC1004 (Ekco T311) spot suppression

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Originally Posted by slidertogrid View Post
I think some dual standard PYE sets had a connection to the neutral on the power switch this provided spot suppression.
They did and importantly, it was directly to the neutral lead so before the switch.
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Old 18th Jan 2023, 6:11 pm   #6
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Default Re: Ferranti TC1004 (Ekco T311) spot suppression

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Have you checked the diagram to see how suppression if any is provided?
Rich
Yeah, there doesn’t seem to be any. The brightness control is just hung between HT and ground with a padding resistor (see pic 1). Not too much of a problem, I just wondered if it was normal. The other minor problem I still have is that the line hold is hard over and once warm, if the signal is interrupted I lose sync and haven't enough range on the control to re-lock it. I've changed or checked all the components in the line Osc stage except the transformer T2 (Pic 2) The only way I can get enough range is to add a 470 ohm resistor in series with the line hold and reduce R112 to 270K. My suspicion is toward transformer T2 - any ideas.
Dave
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Old 18th Jan 2023, 8:09 pm   #7
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Default Re: Ferranti TC1004 (Ekco T311) spot suppression

Oh the switch-off spot! Yes a lot of sets showed it. No-one ever took any notice since it was normal (with most sets) at the time. There used to be a joke going around that some kids will watch the TV all the time and won't stop until the spot fades away......

My little Fergy portable (model 45) has a switch-off spot. I had thought about modding it in the same way the Pye used to do it (as in the threads above) but it doesn't seem to bother the tube so probably not worth it.
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Old 20th Jan 2023, 10:19 am   #8
G8vsjDave
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Default Re: Ferranti TC1004 (Ekco T311) spot suppression

Tried re-wiring the brightness control to mains neutral lead before the switch - works perfetly, thanks.
Dave
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