20th Feb 2021, 4:30 pm | #101 |
Pentode
Join Date: Jan 2021
Location: York, North Yorkshire, UK
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Re: My first telly TV22
Bit dim still
I might try the diodes again and adjust the ion trap as suggested by Helder |
20th Feb 2021, 4:48 pm | #102 |
Pentode
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Re: My first telly TV22
I disconnected the EY51 and put the string of IN4007 diodes back in. Adjusted the ion trap. If I adjust for max brightness it’s still a bit blurred , if I back off slightly from max brightness it’s about as good as it’s been so far.
Brightness control on max , reducing brightness caused width to increase and height to decrease. Not much actual reduction in brightness till towards the bottom of the range and it tends to lose lock then as well |
20th Feb 2021, 4:49 pm | #103 |
Pentode
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Re: My first telly TV22
Think I will get a new EY51 , is it worth getting a new PL81 too?
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20th Feb 2021, 4:52 pm | #104 |
Pentode
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Re: My first telly TV22
Corona discharge seems to have gone , maybe the humidity has reduced
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20th Feb 2021, 5:30 pm | #105 | |
Hexode
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Re: My first telly TV22
Quote:
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20th Feb 2021, 6:40 pm | #106 |
Pentode
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Re: My first telly TV22
I would say focus is better towards center of focus magnet adjustment
I have adjusted picture centering and line linearity and apart from not being the sharpest picture it’s not bad - I’m not really sure what to expect from a 70 year old telly. Good news is the LOPt seems to be running nice and cool |
20th Feb 2021, 6:42 pm | #107 |
Pentode
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Re: My first telly TV22
Ordered a NOS EY51 and PL81 should I get a line drive valve too , read these lead a hard life
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20th Feb 2021, 7:28 pm | #108 | |
Hexode
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Re: My first telly TV22
Quote:
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20th Feb 2021, 7:56 pm | #109 |
Pentode
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Re: My first telly TV22
Presume those are the two bands furthest to the right?
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20th Feb 2021, 7:57 pm | #110 | |
Heptode
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Re: My first telly TV22
Hi Travellingwave.
Quote:
I'm also confused as to why reducing the brightness would cause the set to loose sync unless you actually mean the contrast control or reducing the brightness is causing excessive corona discharge. Cheers Andy
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www.youtube.com/user/andyvalve100 Last edited by beery; 20th Feb 2021 at 7:58 pm. Reason: Left out the word backwards |
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20th Feb 2021, 8:04 pm | #111 |
Hexode
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Re: My first telly TV22
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20th Feb 2021, 8:08 pm | #112 |
Octode
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Re: My first telly TV22
Seem to ask this alot, but are you using an attenuator with the hedghog, needs to be
something around 18dB. It may be overloading the set.
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Stephen _________"It`s only an old telly" ___ |
20th Feb 2021, 8:10 pm | #113 |
Hexode
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Re: My first telly TV22
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20th Feb 2021, 8:12 pm | #114 |
Hexode
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Re: My first telly TV22
On the other hand, if the contrast is somehow stuck to a high value (pot or resistor?) then attenuating the Hedgehog output can be a good idea at this stage.
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20th Feb 2021, 8:17 pm | #115 |
Pentode
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Re: My first telly TV22
No I don’t have an attenuators.
I’m just going to fire her up and see what gratings I can resolve Thanks for all the help , would be lost without |
20th Feb 2021, 8:20 pm | #116 |
Hexode
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Re: My first telly TV22
Fixing the pot/resistor issue in the contrast control should help a lot. You mention that the control only works when at maximum position, which is way too much assuming that everything else is ok. I believe it will be difficult to see fine gratings in these conditions.
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20th Feb 2021, 8:33 pm | #117 |
Pentode
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Re: My first telly TV22
Thanks Helder , I think you are right , if I turn the contrast down the picture shrinks and goes further out of focus , if I turn further something is going into oscillation , still have a frame but just noise.
In terms of gratings - I assume we are talking about vertical bars If I adjust ion trap for max brightness I would say I can see the first three though they are not clearly defined. If I adjust ion trap to a dimmer picture they are much sharper and can get all except the last one. |
20th Feb 2021, 8:42 pm | #118 | |
Hexode
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Re: My first telly TV22
Quote:
As for the oscillation, it seems that you loose line synch (horiz. hold), which can happen if contrast is too low/high. |
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20th Feb 2021, 9:11 pm | #119 |
Pentode
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Re: My first telly TV22
Why would contrast affect picture size? It’s way back from the time base circuits? Anyway will have a look tommorrow
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20th Feb 2021, 9:13 pm | #120 |
Pentode
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Re: My first telly TV22
Anyway - glad there is something to fix , it would be boring otherwise
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