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Old 15th Aug 2021, 1:51 pm   #21
EF80TVVALVE
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Default Re: Ultra V17-60 Television

Boxdoctor, thanks for the information regarding Electro High Vacuum, it isn't one I've heard of before but I presumed they must have been fairly local. The CRT is nice and looks to have good life in it still.

Peter, you are correct it would be the frame scan that I am having some trouble with. It looks be caused by the sliding switch on the tuner, it throws across when switching from Band I to Band III. The contacts are heavily tarnished and in band III I have a very good stable image, band I has the scanning issue which looks to be caused by poor contact on this switch.

I've taken some more off screen photos today, the picture is now the best it's been yet, I'll focus on the tuner over the next week and hopefully get it sorted.
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Old 10th Sep 2021, 6:56 pm   #22
EF80TVVALVE
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Default Re: Ultra V17-60 Television

Hi all

Just returning to this thread after a holiday, I'm back at the V17-60 and I'm hoping to cure the fault previously mentioned with lines jumping somewhat and also some overall frame shrinking when it's happening. I've now made a YouTube video as it will show it better than I can describe, I'm thinking that I should focus my attention around the 30P12 frame amplifier valve, I can test the valve on an AVO tester for any shorts or intermittance.

Just to note it doesn't do this constantly, it settles down but returns after some time before re-settling.

Here's a link to the YouTube video: https://youtu.be/zCn29OQHqU0

Any thoughts would be appreciated.
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Old 10th Sep 2021, 7:30 pm   #23
1955APREN
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Default Re: Ultra V17-60 Television

Hi all
Just looked at your youtube video my first bet is the cathode by pass cap on the frame output valve , just solder a 250Uf 25v across just to try
hope it works
derrick
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Old 10th Sep 2021, 8:06 pm   #24
EF80TVVALVE
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Default Re: Ultra V17-60 Television

Thanks Derrick, actually one I haven't replaced so thanks for pointing it out, I'm sure a modern one can be fitted easily to the underside of the chassis so I'll try that next and see where we get.
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Old 11th Sep 2021, 7:50 am   #25
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Default Re: Ultra V17-60 Television

The 30P12 was liable to suffer from self oscillation [Barkhausen] and may be the cause of the problem. A Mullard PL82 can be used as a test replacement. J.

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Old 11th Sep 2021, 1:42 pm   #26
EF80TVVALVE
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Default Re: Ultra V17-60 Television

Hi John, this is initially what I was thinking myself, it almost looks like a visual representation of a noisy valve. I going to change the cathode bypass now and see what results that has and go from there.

Cheers
Bren
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Old 15th Sep 2021, 7:36 pm   #27
EF80TVVALVE
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Default Re: Ultra V17-60 Television

Hi all,

Just thought I'd update the thread. The replacement 30P12 arrived today (a nice NOS Pinnacle PL801), the old valve didn't test well at all and barely had any getter left either, presumably it was the original and seen almost 20 years of use.

I eagerly powered the set up to be met with the exact same results. I decided to go back and think, the fault looks very much like dirty/scratchy contacts so I decided next in line was the height control as the fault was also causing some decrease in height when misbehaving. I fought to remove the cover of the potentiometer and eventually did then applied some servisol and cleaned it up.

After putting the control back together I again powered up and have since been met with a very good, stable picture.

Next job is to cure the background 50hz bars, which after changing more caps aren't as bad as they initially were although I'd like to get the picture spot on. It certainly gives a very good picture on 405, certainly up there with one of the best I've seen myself.
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