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Old 3rd Dec 2023, 5:02 pm   #1
johnmarshmanagain
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Default Bush TV63 Narrow Vertical Strip on CRT

Hi again All.
The aforementioned Bush (with lots of cap's done, though not all exact) is only giving me a narrow strip, as you will see.
The cold resistance across points h and j is about 50 ohm, as per the sum of L36 and L37 (as shown), and I cut out C63 as it was suspect s/c.
This may be irrelevant, but the sync sep' transformer (for phase discrim, I think) is o/c, but there are other threads on this subject.
Thoughts welcome
Thanks John
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Old 3rd Dec 2023, 5:45 pm   #2
johnmarshmanagain
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Default Re: Bush TV63 Narrow Strip on CRT

Update : I turned up the brightness to full, and fiddled with the jumper above R71, and now have more width - albeit with that puzzling bright band effect, as though the line scan sawtooth is not awfully sawtooth ?. Should I invest in a scope ? thanks john
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Old 3rd Dec 2023, 5:50 pm   #3
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Default Re: Bush TV63 Narrow Strip on CRT

Looks like incorrect capacitor value, Wrong connection. Very unusual fault for a Bush TV56/66 etc. Was the pic the correct shape before you changed the caps? J.
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Old 3rd Dec 2023, 6:07 pm   #4
HamishBoxer
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Default Re: Bush TV63 Narrow Strip on CRT

Possibly caused, as stated by CCCD. Compulsive Capacitor Changing Disorder. Nothing worse than man/woman made fault.
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Old 3rd Dec 2023, 6:22 pm   #5
johnmarshmanagain
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Default Re: Bush TV63 Narrow Strip on CRT

Thanks Gents..... CCCD indeed ! I didn't power up until I thought I'd changed any cap that might s/c the HT, or put the LOPT at risk : I'll retrace my steps.
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Old 3rd Dec 2023, 6:50 pm   #6
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Default Re: Bush TV63 Narrow Strip on CRT

CCCD. I nearly lost my coffee
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Old 17th Dec 2023, 1:47 pm   #7
johnmarshmanagain
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Default Re: Bush TV63 Narrow Strip on CRT

Thank you for the constructive comments
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Old 17th Dec 2023, 8:18 pm   #8
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Default Re: Bush TV63 Narrow Strip on CRT

Quote:
Originally Posted by johnmarshmanagain View Post
Hi again All.
The aforementioned Bush (with lots of cap's done, though not all exact)
....yes...errr 'though not all exact'.... Well given the preferred values in use today like 0.047uF instead of 0.05uF which won't make one scrap of difference, what do you mean by 'not all exact'? There might be some 'wriggle room' in some parts of the circuit where fitting a 0.22uF in place of a 0.1uF (for example) wouldn't make any difference (like an HT decoupler) but in the line oscillator, sync separator, blanking or the frame scan it will make a lot of difference.

Recheck what you have done.
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