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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 20th Jan 2020, 8:18 pm   #21
Greycon
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Default Re: 12" P4 Phospher CRT

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Originally Posted by linescan87 View Post
I'll could help you out with this for some beer tokens, feel free to PM me.
Hi John Joe!
Terminal arrived in one piece. I spent the weekend cleaning it all up, keyobard disassembly, electrical contact cleaner, cleaned the PCB on both sides, checked the CAPs as best as I can. In short, it's working very well.

One minor annoyance, the image seems to jitter over and back by a millimeter or so. It's not the end of the world , but if you have any clue what might be causing it, i'd love to know!
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Old 20th Jan 2020, 8:46 pm   #22
linescan87
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Default Re: 12" P4 Phospher CRT

Could be a line sync issue, possibly caused by poor electrolytic caps. Great news that the CRT is ok.
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Old 20th Jan 2020, 8:55 pm   #23
dragonser
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Default Re: 12" P4 Phospher CRT

HI,
I think I had some strange problems maybe similar to the above ? and found that the switch that selects 50 or 60 hz had been set to 60hz...
but changing the caps carefully might well be a good idea...
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Old 21st Jan 2020, 6:43 pm   #24
Greycon
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Default Re: 12" P4 Phospher CRT

@linescan87 @dragonser I am using a decent 220V to 115V stepdown transformer unit. I changed the linesync DIP in the terminal switch to 50Hz and the cursor started rolling up the screen, so I assume the stepdown transformer unit changes the line frequency to 60hz, but I will check that later.

I can live with it, it's pretty minor, but I'm just curious as to how I might debug it. (I have a good scope and the full schematics for the ADM.)
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Old 21st Jan 2020, 8:19 pm   #25
kan_turk
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Default Re: 12" P4 Phospher CRT

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Originally Posted by Greycon View Post
@linescan87 @dragonser I am using a decent 220V to 115V stepdown transformer unit. I changed the linesync DIP in the terminal switch to 50Hz and the cursor started rolling up the screen, so I assume the stepdown transformer unit changes the line frequency to 60hz, but I will check that later.

I can live with it, it's pretty minor, but I'm just curious as to how I might debug it. (I have a good scope and the full schematics for the ADM.)
Unlikely that the transformer changes the frequency - more likely that the terminal runs at 60Hz - this would not be unusual and is unrelated to the mains supply frequency

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John
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Old Yesterday, 11:57 pm   #26
Greycon
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Default Re: 12" P4 Phospher CRT

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Originally Posted by kan_turk View Post
Quote:
Originally Posted by Greycon View Post
@linescan87 @dragonser I am using a decent 220V to 115V stepdown transformer unit. I changed the linesync DIP in the terminal switch to 50Hz and the cursor started rolling up the screen, so I assume the stepdown transformer unit changes the line frequency to 60hz, but I will check that later.

I can live with it, it's pretty minor, but I'm just curious as to how I might debug it. (I have a good scope and the full schematics for the ADM.)
Unlikely that the transformer changes the frequency - more likely that the terminal runs at 60Hz - this would not be unusual and is unrelated to the mains supply frequency

Rgds
John
OK, it's that there is a DIP switch inside the terminal that has to be set to either 60Hz or 50Hz, and the manual says to set it to match the line frequency. I am hoping to get back to playing with on on Friday
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