paperboy-k4915 med res, can't get the screen to hold

tron guy

Super Moderator
Staff member

Donor 12 years: 2011, 2015-2025
Joined
Jun 26, 2007
Messages
23,144
Reaction score
2,591
Location
Eureka, California
paperboy-k4915 med res, can't get the screen to hold

when I picked it up It was having trouble "sitting" in one place.

I decided to recap the monitor and reflow solder all over the chassis.

I plugged her back in and I have the same issue. if I get the picture adjusted so I can see player one score and high score it starts to roll. I think it will hold with a much too large screen, but at that point I can't see my lives or papers left or high score.

what should I be looking at to fix this?
 
there was not a cap in the kit for the little board that sits up on the left side as you are facing the back of the monitor, not sure if that is relevant, though I figure it probably isn't.

curiously, there is a spot where a wire is coming through the top of the chassis, into the bottom and connected to the frame, near the vertical damp pot. probably a factory thing?
 
Check the sync connection, I had an issue with my 4901 where it worked directly with a game, but not with an inverter board, and I had to change my sync from being bridged between H and V neg sync to just V sync. Now I am able to keep it from scrolling
 
I had the same issue with my ROTJ. Did everything I could think of and finally just sent my main PCB to Elektron Forge. The only reason I'm thinking it's the PCB is that I have a couple of other weird issues as well. Haven't received the diagnosis or received it back though :(
 
Check the sync connection, I had an issue with my 4901 where it worked directly with a game, but not with an inverter board, and I had to change my sync from being bridged between H and V neg sync to just V sync. Now I am able to keep it from scrolling

This connector only uses the 6 plug connector. There is no wires or even a 3 plug present. Anyone with a paperboy that has a 4900 care to chime in on the wiring to the chassis?
I can check the wiring that is there to see if it's solid though.
 
have you tried to replace or clean the pot on the chassis that might effect hold? If nothing else and you want to test your main board set you can bring them by my place and test them in my machine. I just need some warning so I can dig the thing out.
 
have you tried to replace or clean the pot on the chassis that might effect hold? If nothing else and you want to test your main board set you can bring them by my place and test them in my machine. I just need some warning so I can dig the thing out.

I cleaned the pot and reflowed solder on the bottom of the chassis to the screen adjustment pots.

both pots (Vsize and Vhold) are 'working' in the sense that they affect the screen. No amount of adjustment between them gets it to hold.
I guess I could pull the wires out of the connector going to the chassis and make sure they are making good connection and go from there.
 
wire connections are good. I guess maybe I order a pot kit from bob and see what happens?
 
well I played that bitch for about 30 minutes last night, then it starts back up again.

bob thinks it could be a weak b+ filter, hopefully he sells the filter cap and I can change it.
 
I am going to change the b+ filter like I said.
Has anyone here truly ever seen a filter cap be the cause of a scrolling screen?
 
To update this in case it helps someone in the future.

I checked the wiring for continuity between the chassis connector and the pcb connector. I wiggled the brown and yellow wires (sync wires) and made sure they were making good connection in those stupid red molex style connectors. Once I got that taken care of the screen now adjusts and holds.
 
Back
Top Bottom