Blue colour has gone from my arcade monitor display - PICS INSIDE

[eggedd2k]

only red and green stay - blue goes and to get it back again i have to wiggle the connector that all the monitor wires go into connected to the pcb the monitor's on.

[AlanS17]

If your wiggling causes it to go in and out, then something is loose. It could be the end of the wire leading into the plug. It could be the end of the wire leading into the harness. Just because it doesn't look loose doesn't mean it's not loose.

[eggedd2k]

fair enough. i'd say if anything it's the wire going into the monitor pcb - wiggling the jamma edge connector which i tried first did nothing. can you repair loose wires like this?

[AlanS17]

Sure. What's your plug look like? The vast majority behave the same way, anyways. A metal pin is crimped/soldered down to a wire, and then the pin is inserted into the back of the plug. When the pin is fully pushed in, it kinda clips into place. I'd bet your crimping is loose.

Just remove the pin, recrimp, and reinsert. You'll probably destroy the pin in the process (if it's not already toast) so you might have to go to Radio Shack or somewhere to get a new one. They're probably a nickel, but you'd have to buy them in a pack.

[eggedd2k]

ok i've just been looking further into this.  blue is now totally gone no matter how much wiggling i do to the connector.

i've used my meter to get a reading from the jpac red green and blue points and they all give out the same reading. i dont know if this is relevant.

the connector on the pcb of the monitor has 6 prongs sticking up. blue is the farthest prong on the left. i should be able to get some photos up later.

is there any way to do a resistance test on these prongs?

is it not looking like it could be the connector on the monitor??


thanks very much for your help!

[eggedd2k]

i've just tested the blue green and red connectors with my meter. no connectivity problems whatsoever - i get the same reading on each colour.  i also did the same when the connector was plugged into the monitor PCB and all colours registered the same readings.

i guess this proves it's the monitor's PCB?

is it worth even looking to get it fixed or am I best to replace it with a 19" computer monitor?

[eggedd2k]

problem solved - for now

the wires coming from the monitor that go to the jamma connector i've rested on the shelf that the jamma board sits on. before they were dangling down the back of the cabinet.  to me this suggests it's the connector with all the pins in you mentioned.  if it happens again and stays like it i'll have to replace and recrimp the pins

[Ken Layton]

Typically the male half of the connector (the one that's on the monitor board itself) develops bad (cracked) solder joints on some of the pins causing intermittent connections. Usually it happens to the outermost pins. The cause is from the connector and cables from the gameboard to the monitor flopping around loose and/or vibration. Resoldering this connector fixes it. You'll have to unbolt the monitor's main board and flip it over to the foil side to resolder the connector pins.

[eggedd2k]

thanks Ken. if the problem persists i'll have to have the pcb out - is this much of a job?

[eggedd2k]

I've attached some photos of the connector and the board.

Is resoldering the pins - or the dodgy blue end pin easy to do?? 

[Ken Layton]

Remove the two screws and flip the board over.

[eggedd2k]

cheers Ken. is it that easy??  what about the wires connected to the middle of the board?  is there anything nearby that's dangerous to touch?  the connector is not loose at all.

also one other thing i just noticed - the pin in question (the blue one nearest the edge) it looks slightly white - whereas the other pins are pin coloured.  presumably this could also be a factor bearing in mind the connector is not loose at all.

[eggedd2k]

there are two small switches near the monitor's male connector on the board. wiggling these ALSO brings the blue back (temporarily)

presumably this means it's not likely to be the monitor's male connector that needs resoldering. it's sounding more likely to be the monitors board as a whole

[Ken Layton]

Those are the sync polarity selector switches. They select what type of sync signal you are sending it: Positive or Negative.