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Re: General Stuff(tm)
Posted: 13 Oct 2023 12:05
by stephen_usher
Oh, and....
Happy Friday the 13th everyone! :D
Re: General Stuff(tm)
Posted: 13 Oct 2023 12:18
by chronicthehedgehog
stephen_usher wrote: 13 Oct 2023 12:05
Oh, and....
Happy Friday the 13th everyone! :D
:fire1:
Thanks
Re: General Stuff(tm)
Posted: 13 Oct 2023 12:19
by stephen_usher
Just remember to avoid walking under any black cats. Apparently it's unlucky.
Re: General Stuff(tm)
Posted: 13 Oct 2023 12:28
by exxos
stephen_usher wrote: 13 Oct 2023 12:05
Happy Friday the 13th everyone! :D
:hide:
Re: General Stuff(tm)
Posted: 13 Oct 2023 13:22
by rubber_jonnie
D'oh, you had to all say it didn't you!!!
:dizzy:
Re: General Stuff(tm)
Posted: 13 Oct 2023 13:56
by PhilC
I am not fixing anything today! Especially not a C128 :fire: :dizzy:
Re: General Stuff(tm)
Posted: 16 Oct 2023 12:54
by stephen_usher
Had another go at the black & white TV last night.
I found some more caps so 90% of the electrolytic capacitors on the board are now replaced. I also did some work on the aerial board.
At one point I had a pretty decent picture, but with some wavy interference but the sound demodulation was off on the tuner to the point where to get sound I had to detune the video quite a bit. Then I knowed the set and the RF input internal amplification seemed to massively decrease. Either I have a bad joint somewhere of there's a control which has some corrosion.
The main issue seems that the whole tuning circuit is out of alignment. The service manual says how to do all this but you need a UHF TV sweep generator and a lot of tweaking, desoldering, soldering just to do the settings.
Don't you just love analogue circuits?
Re: General Stuff(tm)
Posted: 16 Oct 2023 13:13
by rubber_jonnie
stephen_usher wrote: 16 Oct 2023 12:54
Had another go at the black & white TV last night.
I found some more caps so 90% of the electrolytic capacitors on the board are now replaced. I also did some work on the aerial board.
At one point I had a pretty decent picture, but with some wavy interference but the sound demodulation was off on the tuner to the point where to get sound I had to detune the video quite a bit. Then I knowed the set and the RF input internal amplification seemed to massively decrease. Either I have a bad joint somewhere of there's a control which has some corrosion.
The main issue seems that the whole tuning circuit is out of alignment. The service manual says how to do all this but you need a UHF TV sweep generator and a lot of tweaking, desoldering, soldering just to do the settings.
Don't you just love analogue circuits?
I was pleasantly surprised to see no obvious failed caps in my PYE colour TV the other week, and after a good clean it seems ok, though I may recap it down the line a bit. My uncle was a TV repair man back in the day, so it's nice to see some TV's getting TLC, but yeah, analogue circuits...
Good luck with your setup.
Re: General Stuff(tm)
Posted: 16 Oct 2023 13:18
by stephen_usher
Well, after 50 years all the caps were dry and out of spec. Not surprising.
Not sure how far I can get without a sweep generator though. I can use computers as a test pattern generator though, so that's OK.
Re: General Stuff(tm)
Posted: 16 Oct 2023 14:00
by rubber_jonnie
stephen_usher wrote: 16 Oct 2023 13:18
Well, after 50 years all the caps were dry and out of spec. Not surprising.
No, not really...
If I'm honest, I don't necessarily trust those in my PYE either, but it's for another day just now.
stephen_usher wrote: 16 Oct 2023 13:18
Not sure how far I can get without a sweep generator though. I can use computers as a test pattern generator though, so that's OK.
Yeah, they seem a bit on the expensive side that's for sure, and probably more than you'd want to pay for repairing an old B&W TV.