model 688-20(pentranic?), dim screen

[kardenm]

I have a monitor with a dark/dim screen (no brightness). Board is labled model 688-20". Is this a Pentranic?  Picture tube is a 20" Hitachi. What is likely cause of the dim/dark picture?   

[codecrank]

first, try adjusting the various pots / knobs on the board and flyback.

Here is a good intro video.

http://www.youtube.com/user/varcadegames#p/u/10/MUL5TiUYAss

[kardenm]

Sorry. Should have told you I alredy tried all the adjustments including ones on the flyback. Still cannot identify the make of the board from the suggested web sites (still trying).

[lilshawn]

if you take a few photos and post them, someone here has probably seen/has it.

[grantspain]

i have a schem for the 888 chassis and i would change c407 10uf 250v cap-not 100% sure if your chassis is the same

[kardenm]

Finally got back to this one. I did suceed in getting a near perfect picture through a combination of adjustments including flyback-screen.  Main problem seemed to be a pot in middle of board labled only VR901.

Also this chasis is a Pentranic model 688.

Thanks for the help. On to the next one.