CRT image trouble

[Dan Beck]

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

 

[Joerg]

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!

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.

 

[Yukio YANO]

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.

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

There is an
isolation transformer

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

 

[Dan Beck]

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

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

 

[Joerg]

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!

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.

 

[Eeyore]

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.
True.


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 :-(

Yes but they were about ten times the size too !

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

Absolutely.

Graham

 

[Joerg]

Yes but they were about ten times the size too !

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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