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Old 20th Feb 2021, 4:30 pm   #101
Travellingwave
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Default Re: My first telly TV22

Bit dim still

I might try the diodes again and adjust the ion trap as suggested by Helder
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Old 20th Feb 2021, 4:48 pm   #102
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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
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Old 20th Feb 2021, 4:49 pm   #103
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Think I will get a new EY51 , is it worth getting a new PL81 too?
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Old 20th Feb 2021, 4:52 pm   #104
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Corona discharge seems to have gone , maybe the humidity has reduced
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Old 20th Feb 2021, 5:30 pm   #105
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Default Re: My first telly TV22

Quote:
Originally Posted by Travellingwave View Post
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
How does your focus magnet behave? Do you cross a point of minimum blur near its centre position? Or is it closer to one of the ends?
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Old 20th Feb 2021, 6:40 pm   #106
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Default 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
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Old 20th Feb 2021, 6:42 pm   #107
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Ordered a NOS EY51 and PL81 should I get a line drive valve too , read these lead a hard life
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Old 20th Feb 2021, 7:28 pm   #108
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Default Re: My first telly TV22

Quote:
Originally Posted by Travellingwave View Post
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
A more quantitative way of checking focus and resolution is looking at the 2.5 and 3 MHz vertical gratings in the testcard. If you can resolve the first, that's already very good and what most of us have. If you can resolve the second, you have a cracking set with impeccable alignment.
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Old 20th Feb 2021, 7:56 pm   #109
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Presume those are the two bands furthest to the right?
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Old 20th Feb 2021, 7:57 pm   #110
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Default Re: My first telly TV22

Hi Travellingwave.
Quote:
Originally Posted by Travellingwave View Post
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
I'm a bit confused by this. Basically, if the brightness control is working then you need to set it to a level where you can just see the raster clearly and then adjust the trap magnet by rotating slightly and moving it forwards and backwards slightly until the raster is at its brightest. If the focus is then off because the brightness is too high, the brightness needs to be reduced using the brightness control. If that does not work, then you need to investigate the brightness control further. It is not a good thing to use the trap magnet to reduce the brightness as it will shorten the tube life significantly.

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

Last edited by beery; 20th Feb 2021 at 7:58 pm. Reason: Left out the word backwards
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Old 20th Feb 2021, 8:04 pm   #111
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Default Re: My first telly TV22

Quote:
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Presume those are the two bands furthest to the right?
Yes.
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Old 20th Feb 2021, 8:08 pm   #112
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Default 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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_________"It`s only an old telly" ___
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Old 20th Feb 2021, 8:10 pm   #113
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Default Re: My first telly TV22

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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.
Or perhaps it's just too much contrast/gain. My Hedgehog II works fine without any attenuation. Same for the Aurora.
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Old 20th Feb 2021, 8:12 pm   #114
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Default Re: My first telly TV22

Quote:
Originally Posted by Freya View Post
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.
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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Old 20th Feb 2021, 8:17 pm   #115
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Default 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
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Old 20th Feb 2021, 8:20 pm   #116
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Originally Posted by Travellingwave View Post
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
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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Old 20th Feb 2021, 8:33 pm   #117
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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.
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Old 20th Feb 2021, 8:42 pm   #118
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Quote:
Originally Posted by Travellingwave View Post
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.
Yes, the vertical bars. That's fine for a quick check, but it's not a good idea to adjust the ion trap magnet to a dimmer picture. You will be overdriving the tube with excessive beam current (and overloading the output stage), even though most of it won't reach the screen.
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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Old 20th Feb 2021, 9:11 pm   #119
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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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Old 20th Feb 2021, 9:13 pm   #120
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Anyway - glad there is something to fix , it would be boring otherwise
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