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Forum 135

B&W TV Another Bush TV22 arrives in the workshop.

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Lloyd
(@lloyd)
Posts: 1958
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Cheers for the info, I’ll give that a try next time I’ve got the set apart!

regards,

 Lloyd 

 
Posted : 29/08/2023 6:36 pm
Doz
 Doz
(@doz)
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Posted by: @lloyd

That’s a nice clear picture! I notice it doesn’t have the usual Tv22 picture wiggle at the top! Mine has a slight fold over right at the top, which just affects the castellations, any idea what causes that?

Regards,

Lloyd

Also, try switching off equalising pulses on the standards converter. Mine hates them.

 

 
Posted : 31/08/2023 2:23 pm
Lloyd reacted
Lloyd
(@lloyd)
Posts: 1958
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Ah, yes, I’d heard they caused trouble, I think they are off on my Aurora, and I did notice they cause the picture to shift vertically when turned on and off on the Hedghog, which does help with the fold over at the top. I’ll have to double check that they are indeed off!

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 Just found this picture that I’d already uploaded a while ago, you can just see the top fold over, which you don’t see when it’s in the case anyway, and a very slight kink in the lines near the top. Whilst rooting through some old photos from my other TV22, it looks like that one also had the kink! That was a damn good set until the lopty gave up 😢.

Regards,

 Lloyd 

 
Posted : 31/08/2023 7:05 pm
Till Eulenspiegel
(@till)
Posts: 4947
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Poor interlace and  operating a Bush TV22 from a standards converter with the EQ pulses switched on was discussed by UKVRRR forum member Argus25.   Dr. Holden rightly observed the frame sync pulses were over integrated. He suggested reducing the 100Kohm resistor in the  frame sync circuit to 10Kohms, it's something you can try.  Note the WX6 clipper diode is not terminated, it's been suggested the internal leakage in the old selenium diode is sufficient to allow the circuit to work during the presence of line pulses.  If a silicon diode is used as a replacement fit a high value resistor across the diode, say >1Mohms.

My own TV22 needs attention so when the KB HV40 restoration job is done the Bush can be attended to next.

Till Eulenspiegel.

 
Posted : 31/08/2023 9:08 pm
colourmaster reacted
Cathovisor
(@cathovisor)
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I never understood the reasoning of introducing something alien to the 405-line system, as in equalising pulses. They were never there in the entire life of 405 lines, so why introduce them?

 
Posted : 01/09/2023 12:32 pm
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