Help on Red gun question

[vader]

I was pretty happy with my Ms Pacman cocktail cause it worked correctly most of the time.  Now when you first power up the machine, red is non existant.  If you give a good tap on the top, the red will flash on and off and sometimes stay on.  After about 20 minutes, it seems to stay on for a good while.  I don't remember but I think it has the Electrome g07 ca0 monitor.  I haven't capped it yet.

Thanks

Tim

[grantspain]

Likely to be just a dry joint on your drive transistor or your neck card,you gonna have to get the chassis out and have a good look at your solder joints.If you tap the chassis and the fault reacts to that then its def a dry joint,unlikely to be cap fault.

[vader]

Since this is beyond my current skill level to understand, can you please post a picture or link to what you are talking about.  I know how to use a soldering iron and have the basic understanding to discharge a monitor.

Thanks

Tim

[grantspain]

dry joints are where the solder connections on the circuit board over time either through heat or physical movement become cracked-its usually obvious when you see one.dont know any links to give you perhaps there is someone else on the forum who could advise,sorry cant help better

[vader]

Thanks for the reply.  I'll have to wait till the summer, in the process of moving and have enough of a mess as it is, don't need to be yanking a monitor out.

Tim

[Level42]

My guess is you don't need to get the complete monitor out. These kind of problems often are in the PCB on the picture tube neck, not on the main PCB. Try to GENTLY tap to see what happens with the red gun. If so, try and see if you see any bad solderings (cracks/moving pin). If not, simply re-solder all the solder points (or do a couple, then test, if not fixed, do another couple, test again....etc.)

Also, I assume you are running the original arcade game (Ms.Pac Man). If not, if you're using a PC and MAME: check your VGA connector on your video-card ! Believe it or not, those screws on the connector are actualy meant to be used ! 
I've worked at a VGA monitor company, repairing them, and about 25% of the returned monitors were FINE, and always with the same complaint: blueish/greenish picture (=No red gun). The pin for the red signal is all the way on the edge of the VGA connector. Those people were too lazy to use the screws on the connector, and it wiggled out....but I may be getting WAY off now

[vader]

Thanks for the reply.  Yes, it is a Ms PacMan machine.....I will open up tonite since the neckboard is very easy to get too.  Should I just reflow solder over all the joints just to be safe, or trace the joint and do just the red one.


Thanks Again...

Tim

[grantspain]

have a look at your neck card using good light-if you have a dry joint then it will be obvious,you dont really want to be soldering everthing in sight as you could drip solder across componants and then you really will have problems,but please concentrate on the tube neck socket and the drive transistors(if there are any on your chassis).
I will give you a little tip as to what i do to locate a dry joint-take a small plastic handle screwdriver and tap gently around the chassis with the handle not the metal,this should pinpoint where the problem is(remember set a mirror up infront of your cab so you can clearly see the screen when tapping),then you can concentrate on that area for the said bad connection.