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]

Dan Beck wrote:

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.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

 

[Yukio YANO]

Dan Beck wrote:

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