Missile Command screen blinks white on and off

[voodoo_chilly]

I have a Missile Command Upright and during a game something went wrong!
Now the screen just blinks on and off as do the player 1/player 2 LED buttons.  Does anyone know where I should start with this problem?  It has an Electrohome G07CB0.  Board is getting 5.0V (was lower...4.4 when I checked but I increased it).  Checked all connections, etc.  Is this a monitor issue?

Thanks!

John M
Jupiter, FL

[voodoo_chilly]

Also note that when I coin-up the game, there are no sounds etc... so maybe NOT the monitor?

John M

[RayB]

Absolutely not the monitor.

Power off. Open the coin door. Look for the panel with the volume control on it. There's a test switch you can slide up or down. Slide it to the other position it's at now. Power on.

You'll probably see the flashing again, but assuming the game board is getting correct power and everything else, you'll hear a series of beeps. The type of beep reports if certain parts of the game are good or bad.

If you don't even get beeps, then something is preventing the game circuit board from operating properly.

[voodoo_chilly]

Thanks Ray-

Heres what I get:

With test switch on, the player 1 light stays lit and the player 2 light blinks.  The sounds I get are like the missiles exploding....kida like at the end when you dont get on the high score list and the screen says "THE END" ...that sound.  The consistent exploding missile sound.  No beeps whatsoever.

John M

[voodoo_chilly]

Also, the screen is garbage...reddish orange and flicker at top and bottom.  Moving trakball does nothing nor does pressing any switches (fire buttons or p1 or p2 start buttons).

John M

[voodoo_chilly]

Voltages out of the power supply from bottom of game read 6.5 and 5.9 and several 3 V....  in manual it says 6.5 V and 25V....  hmmm no 25V

I have to sleep now but will check responses tomorrow....and recheck my voltages checks.

Thanks guys.
John M

[RayB]

Post photos.

Download this: http://www.crazykong.com/manuals/MissileCommand.man.pdf

... and read the part about self-test (describes the beeps and noises it makes).

It says "a continuous raspy tone means vblank is malfunctioning". VBLANK has to do with drawing the screen graphics. So, components that control graphics are not working. Could be chips, or could be other parts that relate to powering those chips. I can't be more specific, sorry.

Regarding measuring voltage, I meant off the BOARD, not the power supply. The board will have points marked "5v", "-5v", "12v", etc. Measure those. The most important is the 5v. If 5v is too high, that may be why some parts have failed.