paperboy 4900 red

paul400

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been working on my paperboy and moved on to the monitor. the red is weak and cant get it to the bright red it should be. replaced the pot on the neckboard and the drive transistor on the neck board and the two on the main board with no good results. I also checked the tube with my rejuvinator and all the colors tested fine. any thoughts from you guys?
 
You could have a bad connector or cold solder joint on the neck board socket. You should also check the video connection on your harness.

At this point it would be good to determine whether it is your monitor or board set. It might be easier to just try your boards in another machine.

Otherwise, I would hook on some test leads and compare color signals with a multimeter/scope all the way up the chain starting with the neck socket. Put the monitor on a test pattern where equal amounts of other colors are present and compare voltages from one color to the other.
 
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Being a med-res game and tube, you might not have the option to test it with another machine.

If your rejuvenator says the red is good, then start at the video input header and follow it through. It goes through a transistor or two, then a chip before going to the neckboard. Check all of that. Look for a voltage drop somewhere...
 
so far i reflowed everything on the neckboard and the header on the main board and all the transistors, took some readings on the neckboard it appears the red voltage wont drop all the way down like the other two. as i turn up the red the volts drop at one point from 5v to 3v while the other drop smoothly to below 1v.
 
just picked up a championship sprint over the weekend with a 4900 in it, so atleast i can determine it is the monitor or something else.
 
i hooked up my newly aquired championship sprint monitor to the paperboy logic boards via bob's extension cables, picture of paperboy looked great, so atleast i know the logic is putting out the right colors. swapped out a resistor that was not right spec and the diode since it was desoldered, did a cap kit just because i had it out and didnt know how how old the last cap job was. results were disappointing, no inprovement
 
New issuse. Screen keeps going dark, then comes back. Sound like a flyback? Still stuck on the colors
 
Sounds like you may have a Paperboy and a Championship Sprint game there--I would try the reverse--hook up Championship Sprint to that monitor and see if it works.

I had this exact problem with one of my paperboy machines...turned out to be a bad connection in the video harness.
 
going in the wrong direction with this chassis, replaced the flyback and blew the fuse put a new fuse in and it worked for an hour, yesterday i powered it up and the fuse blew again, replaced it and blew the fuse again. HOT seems to test good.
 
You could have a bad connector or cold solder joint on the neck board socket. You should also check the video connection on your harness.

At this point it would be good to determine whether it is your monitor or board set. It might be easier to just try your boards in another machine.

Otherwise, I would hook on some test leads and compare color signals with a multimeter/scope all the way up the chain starting with the neck socket. Put the monitor on a test pattern where equal amounts of other colors are present and compare voltages from one color to the other.

finally got this one fixed, you called it,bad header pin/cold solder on the board. soldered a new one in and adjusted to a clean picture.
 
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