Wells Gardner 4906 chassis issues Horizontal white line at top

[tnglc79]

I have been working on an original Galaga for some time now. Once I got the boards working everything was good so I decided to let it run overnight. At some point the monitor died. I recapped the chassis (Well Gardner 19k4906) and picture was back and all was well. I left it on overnight again and now I have a white section about two inches across the top of my screen. I hate to admit it but I am at the point of defeat with this thing. Maybe one of you know what this issue is or can help point me in the right direction. I have attached the clearest image of my problem.

I can and will supply any info you may need as well.

[baritonomarchetto]

Start by checking resistors on the neckboard first.

[tnglc79]

Will do, I am pulling the chassis again tonight. I will post my findings. I haven't been able to locate any others with this exact issue so maybe once it's figured out someone else can benefit from this.

[tnglc79]

Pulled all resistors, including VRs and tested values. Everything is within the 5% tolerance. Obviously in this process I 100% depopulated the board, cleaned it, inspected it with 8x magnification and repopulated the board. While I was at it I checked the transistors even though I was fairly certain they were not an issue. All checked perfect. Cleaned all neck adapter pins and socket.

No luck. Picture is a little cleaner, but still same issue.

Any other ideas?

[ed12]

1 of the caps u put in has failed
chk the vert circuit,look's like a coupler has gone or is going south on you.

ed

[baritonomarchetto]

You have a failing resistor or bad cap in the video amp circuit or vertical deflection circuit there.
You should now go backward with schematics by hand and check components on those circuits

[tnglc79]

Quick question. My anode is on the right side of the screen looking at it from the front, would that not be a horizontal issue? The horizontal controls move the screen up and down where the verticals move it left to right. This is the original tube and chassis for this machine, got it from original owners who knew repair history.

[baritonomarchetto]

Yes, you are right. Triple check your capkit work

[tnglc79]

I have been through that cap kit 3x's. I have changed the values between a couple of them that are different between the 4900 and the 4906 chassis. Namely the 100uf 160 and the 47uf 160. Found a mod on the board that causes vertical collapse if removed, figured it out with no mod now, but same issue on the horizontal. I should have some time on Wednesday to dive into this guy some more and hopefully figure it out. I picked up 5 chassis at an auction this weekend so I will have some donor pots and ics, may have a good chassis in it, but I will still figure this one out. Can't stand to be beaten.