Neotec 2515C intermittent blue tint?

[novamatt]

So it seems I'm getting an education on arcade monitors the hard way.  Last weekend I installed a new cap kit and flyback, but forgot to screw the HOT back into the metal plate.  The monitor looked awesome for a few hours until the HOT blew (totally my fault, but I learned something, right?).

Yesterday, I replaced the HOT and the largest cap on the board, which wasn't included in the cap kit, but was obviously leaking.  When I finished that, I checked and adjusted the B+, since I see that mentioned on here as being super important - it was about 3V over the recommended setting and the manual gives it a +/-0.5V tolerance.  Now it's about 0.2V under.  I can't get it dead on because the pot is too sensitive.  Even the slightest nudge pushes it up to 0.7V or so over.  It's within the tolerance, so I assume it's fine.

So again, my monitor looked awesome.  But again, for a few hours.  The latest issue is that every couple of minutes, the whole screen will take on a blue tint for a second or two, then flip back to normal.  These "blue times" seemed to be getting closer together and lasting longer.  It started after a couple of hours of use.  Since I thought it might be heat/usage related, I turned the monitor off when I noticed it was getting worse.  Has anyone seen this before?

I'm running it in a cab with a brand new ArcadeVGA 3000 (using Ultimarc's video amplifier) running GroovyMame 0142.

tl;dr - new caps, new flyback, new HOT, B+ good, intermittent flashes where the whole screen's tinted blue for a second or two.  They're getting closer together and lasting longer.

Thanks!

[grantspain]

I would look at the transistors on the neck card

[MonMotha]

I'd start by reflowing the solder joints on the three color transistors.  Intermittent failures like this are often heat related due to expansion/contraction and cracked solder joints.  Failing that, swap the blue transistor with one of the other two and see if the problem moves.  You might also try tapping (gently) on the neck board and tube neck and see if that causes the problem to manifest itself (watch out: neck is hot).  Also check if any of the adjustment pots are dirty or otherwise failing.