Vertical scrolling issue

[Bigcat76]

Need help, I'm new, just got this original blue cab DK, I twicked the v-cent knob just a hair.. it went haywire, started scrolling, cannot get it back for the life of me .. I should have never touched it!!

[Bigcat76]

I'm sure this has been asked and asked, also should be an easy fix. How it you move the v cent a hair, one way move it back where it was and nothing?? Heeeeeeelp!

[aarontruitt]

sometimes those pots have a very small sweet spot - keep turning it back and forth VERY slowly until you get it aligned again. if turning the pot isn't doing anything at all, the pot needs to be replaced.

[YesAffinity]

Here's some good instructions on cleaning pots.  That might be a good place to start, but if that doesn't work, then as aaron said, replacement is your only option.

http://electronics.stackexchange.com/questions/2535/how-to-clean-a-potentiometer

To clarify, did you adjust the pot on the game board?  If not, exactly which one did you mess with (see the attached diagram, to identify which one it was)?  I ask because if it is on the chassis, it would probably be a good idea to discharge the monitor before trying to clean the pot.

Lastly, if you have further questions on this topic, it might be better taken to a dedicated thread, as this thread you posted in is about PCB roms and game versions.   

[Bigcat76]

Thanks so much for the info. It seems impossible, I won't get to it til fri, I messed with the one to the left, where I think 5 knobs are, the V-cent I believe, thanks again, it's probably dirty, it's all original. Thanks again,