Taito Superman Game Grouding or Cap issue?

[ScottChez]

Help
I have a 1988 Superman Arcade that I am restoring.

Everything now works fine except when playing the game some of the colors are not solid.  They quickly flash on and off every 1/2 seconds at a very constant rate.
I confirmed that these colors should be on full time.

Examples of what I am seeing:

1-Superman   Player2 RED should have Solid colors.

2-When I put the board in test mode it confirms they colors are not solid.

3-Sometimes background colors like Blue are solid, but Superman are not solid, they flash.

4-At the start up screen where the Taito logo should be solid it flashes on and off with a White background on and off where it should just be a solid log.

I have confirmed it is not a monitor issue as I plugged in an other Jamma based game the colors are perfect.  (this was in the monitor thread).

Photos show 1/2 second colors are there, next 1/2 second they are not.  Blue and white seems good in test pattern but not in the game where Blue is not always solid on Superman.

Here is a crazy one.

I found that my using a piece of plastic and then pushing down from the circuit board site over one of the Graphics chips that most of the time it is 100% normal.

If I push down with an insulated screw driver it does not.

Is this some kind of ground or Cap issue?

[ScottChez]

New info.
If I let it run for 30 mins the colors get a lot better, BUT only after I power cyclel it (reboot after 30 mins)
 but
 there is still some flashing on Red and Blue, and some White so it is still not right.  Green will start to show on the bottom square in the test pattern above but the top left ones still flash.

With the other game I plug in everything is perfect at the start all the time so I know its not the monitor warming up.

Makes me think its the board,  Caps, Chips, Solder joints?  Ideas?

[mgb]

Did you clean the jamma edge connector and did you pull and reseat any socketed chips. Many times this fixes alot of problems.
also sometimes socketed chips need to have he legs cleaned.

[ScottChez]

I pulled all the chips as suggested, no improvement.  I did not clean the connectors though.  Any suggested methods on cleaning?

Any suggestions on how to test Video Chips? If that is it?

I did notice that if you let it warm up some of the colors come back and stop flashing but the important graphics like Superman and the score, and the power level bar at the bottom do not.  Also the sky is never blue.

[mgb]

If the legs of the chips aren't super disgusting looking, a pencil eraser can work. Be careful not to damage them.

On older boards that have real dirty chip legs, I use a dremal tool on low with a wire wheel. But when doing this you need to be super careful because its easy to break one of the legs.

Because you tried another board and all looked good, it seems you know that all cabling and connections are good.

Did you clean the jamma edge connector on this board? Again with a pencil eraser.

If it seems to get better as the game warms up, you may have a bad chip.
One test you can do is start the game and somehow warm up chips one at a time with a blow dryer or something not to big or too hot.
Of course you will only wanna focus on chips that pertain to video. No sense in wasting time on a sound chip or something.
Alternatively you can let the game warm up and then freeze chips one by one using either freeze spray or canned air upside down. Be careful not to get the coolant on just anything.

Also some boards have diagnostic menus which may help.

[mgb]

Also is the daughter board reseated

[ScottChez]

I cleaned everything and checked the daughter board.  I then checked most of the traces to the video chips areas.
Nothing helped.

In my testing I did find something strange.  Everything you turn it on or off you get different colors working better or worse.
For example in the test pattern on the diag screen the greens may all come on or more blues.

Maybe a better description is many of the graphics are Oscillating and a set frequency so I was looking at the video but that was no help.  Plus  I know the monitor is good as other Jamma boards look ream good.
Ideas?

[ScottChez]

Here is a crazy one.

I found that my using a piece of plastic and then pushing down from the circuit board site over one of the Graphics chips that most of the time it is 100% normal.

If I push down with an insulated screw driver it does not.

Is this some kind of ground or Cap issue?

[mgb]

It could be a bad socket

[paigeoliver]

I would just buy another board, there is one on ebay with an $85 BIN with free shipping, which means you could probably get one for $50-$60 on the arcade-museum (Klov) forums.

[lilshawn]

I'm getting the feeling you have some crummy old sockets that need to be replaced. the round machined type (LEFT) are allot better then the spring contact type (RIGHT). the springs lose their springiness and you get a bad contact on the leg.