Missile Command UR help needed

dyrwolf

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On prior thread, I checked out all the power brick voltages and they are fine.

Looks like the voltages on the PCM board are fine.

Looks like the voltages on the sound board are fine, but a couple register 1/2 what they should. I seem to remember from working on these that I need to go +22 to -22 to see the 22 volts? Regardless, all test loops are showing something, either correct or 1/2 correct.

I got no sound. I got an bunch of weird stuff on screen, nothing discernable, but is different depending on whether in test or play mode. So some sort of image signal is going to the screen. Coin solinoid activates.

No 1/2 player lights are lit.

Looking for some direction and guidance.

1. I am going to put in a new monitor, either the new ones from 2-bit or an LCD. Any suggestions or comments are welcome.

2. Should I pretty much just pop in new/fixed board and monitor? Or is there something else I should try before declaring the board bad.

Thanks in advance. I want to make sure I can get it workign before I put money in the cosmetics.
 
Forget about the +/-22 as Missile Command doesn't need or use either of those voltages.

As you already appear to have the PCB plugged in to the AR2 output, check for the +5, -5, and +12 at the relevant main PCB test points.
 
Thanks. Results:

1. Both player start lights lit but dim. Nothing when I press them although free play active. No sound.
2. Can hear sound in test mode. Number 6 high pitch, indicates this is J4 RAM. I looked at card and it is soldered in. It is the soldered in one with J4 next to it? TI chip.
3. Screen is white rolling in play mode, red vertical bands with yellow at bottom in test mode.


Replace J4 chip?
 
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