Testing Space Invaders Board

orion3311

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Two questions regarding Space Invaders boards...

1. Can the motherboard be tested without the daughterboard, even just to get the vertical lines?

2. Is it possible to get a standard edge connector to make a test rig instead of the funky one the original harness has?
 
Two questions regarding Space Invaders boards...

1. Can the motherboard be tested without the daughterboard, even just to get the vertical lines?

2. Is it possible to get a standard edge connector to make a test rig instead of the funky one the original harness has?

1: Not sure...

2: Yeah, shouldn't be an issue. It'd probably be a good idea to order 2 sets and replace the connectors in the cabinet as well if the board is good. Mine doesn't have the greatest connections anymore... but as long as I don't rock the machine too much, they work. WHERE to get them, I'm not sure, but I'm fairly sure (hopefully) they're out there.
 
So far it seems you can, although this board is really DOA. One of the 9233's at F6 was getting red hot, and after doing some prodding I found it had 12v going to pin 10 which was an address bus, meaning any roms that would have been in the board (thankfully there weren't) would have been toast. After some careful inspection I found a squashed trace on the back that was shorted to that line.

12v on a logic chip I guess = bad, yet the chip still shows outputs.

Processor seems to be dead, almost nothing pulsing. Not sure if its in watchdog or not.
 
The answer is probably going to be no - I traced the reset line from the processor back to the daughterboard plug - the reset line had nothing on it, and plugging in the daughterboard at least got it high, so the daughterboard is required for it to function.

That said - this is still dead as a doornail.
 
So far it seems you can, although this board is really DOA. One of the 9233's at F6 was getting red hot, and after doing some prodding I found it had 12v going to pin 10 which was an address bus, meaning any roms that would have been in the board (thankfully there weren't) would have been toast. After some careful inspection I found a squashed trace on the back that was shorted to that line.

12v on a logic chip I guess = bad, yet the chip still shows outputs.

Processor seems to be dead, almost nothing pulsing. Not sure if its in watchdog or not.

Depending on how the motherboard is strapped......you could have 12VDC at the ROMs.....TMS2716's......2708's both use 12vdc.......still, as you noted, you shouldn't have 12VDC at the 9233.

Edward
 
I figured that much but it was pin 1 which is an address line (A1). The trace runs along the edge of the board right next to a 12v bus, apparently got hit somewhere and it smeared to the address bus. As soon as I fixed the smear/short, the 12v went away.

I picked this up at the Allentown show for cheap - figured if I learn something and maybe get a board running, then good. If not and it goes up in smoke...oops.
 
To add to this - not only do you need the daughterboard plugged in, but you also need the 11 pin connector connected as well. The 11 pin connector carries the 18v audio supply as well as the reset line from the power supply.

The 8 pin connector is only for player controls and not needed just to get a test screen.
 
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