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CRT image trouble

Hello all,

years ago I installed a new Happ 13" CRT in a video game I own. The game probably has about 20 hours on it since I changed the tube; my children don't play it anymore...

Anyway, the image appears to be undulating, at all times. There is an isolation transformer in the game that powers it, with a freshly repinned power connector. A fellow suggested I unplug the degauss loop connector from the main pcb; that resulted in no change. The electrical outputs from the game mother board include repinned connectors and shiny "fingers" on the board edge connector. The little pcb with the horizontal/vertical/brightness/contrast pots I have fussed with, with no dice.

Any other thoughts? Thank you in advance for reading, and any ideas you may have!

Regards, Dan

Reply to
Dan Beck
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Possibly a capacitor in the power supply has dried up a bit, lost lots of capacitance, and now the supply line for the vertical deflection of for horizontal (or both) has a huge 60/120Hz ripple.

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Regards, Joerg

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Reply to
Joerg

This transformer is magnetically coupling to the Neck of the CRT !!! Reposition it to minimize coupling to the CRT Yukio YANO

Reply to
Yukio YANO

Hello all,

I am posting this as a follow up for the archive. I spoke with a tech at Happ Controls about this model of monitor. It does not require an isolation transformer. I removed the isolation transformer in my game, and I still have the undulating image. The tech suggested that even thought the monitor is only 8 years old with minimal use it probably needs a cap kit.

Thank you all for the suggestions and ideas!

Regards, Dan

Reply to
Dan Beck

Sadly, the average quality of electrolytics (especially larger ones) has deteriorated significantly. I have here a few radios from the 50's, all with their original electrolytics and fully functional. These things get hot in there and heat is the enemy #1 for electrolytics. Yet none failed in about 60 years. I guess that's kind of impossible these days. Or in plain English, not everything in electronics is progress :-(

If you put new caps in there make sure to get 105C grade. A few cents more but well worth it.

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Regards, Joerg

http://www.analogconsultants.com/

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Reply to
Joerg

True.

Yes but they were about ten times the size too ! :-)

Absolutely.

Graham

Reply to
Eeyore

Not necessarily. As a kid I scrapped some smaller electrolytics out of TV sets. Not to pinch pennies but because I didn't trust the stuff from electronics dealers. Just for fun I measured a few with date codes from the early 60's. Without exception all above their rated capacitance and no leakage to write home about.

[...] 
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Regards, Joerg

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Joerg

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