Welcome! You're in the right place.

If you don't have a copy of the manual, you can download it from ipdb.org. here's a link directly to the download: https://www.ipdb.org/files/1415/Data_East_1987_Laser_War_English_Instruction_Manual_with_paginated_schematics_better_resolution_right_half_missing_for_pages_25_34.pdf

What you're experiencing sounds like a switch matrix problem, since multiple switches on the same vertical "Column" (in the manual called a "Switch Drive") aren't working. I would also check the other switches on Column 4 as graphed on the switch matrix chart: 1339375765.png

You may find some or possibly none of those switches are working. Most common reason is a wire or diode broke off *any* of those switches on Switch Drive 4 aka "Column" 4 (the vertical row of switches circled above). I'd examine each of the circled switches. Give the green-yellow wires at those switches a light tug to make sure they're firmly connected at all 7 switches. Do the same for each of those switches diodes at both ends as well. All of those switches with the green-yellow wire are on the same circuit--the wire runs from one switch to the next, to the next, and finally goes up the backbox to the CPU board at connector CN8 pin 4. If you look at that connector on the CPU board, you'll see it is the same green-yellow wire. You can pull that connector and put a probe from your multimeter on CN8 pin 4 and see if you get continuity from there to the green/yellow wire at each of the playfield switches circled above.

In short: you're looking for a green-yellow wire or a diode leg at one of those circled switches broke off or possibly touching something it shouldn't. You'll note multiple green-yellow wires at most of the switches, make sure they're *all* firmly connected to their respective solder lugs.

Good luck! Be sure to ask any questions if you are unsure moving forward, pin repairs can be tricky for the uninitiated (and for those of us that are, for that matter )

I don't think that's what you're looking for, but that may be for a flash lamp circuit or something else. Reconnecting that may get certain flashers working or something. Not sure! If that doesn't fix the switch problem, go through the switches as described in my post above.

frunch is right. those warming resistors are for flashers and if you reconnect it and you have LED flashers it will lock on.

You need to locate those 3 switches under the playfield and verify the wiring on them. Also check those 3 yellow switches are they working? If not you may have a column out

I'm the friend! Thanks for the note about that resistor - I'm a #44 snob so not terribly familiar with LED yet but felt it was important to check if it was done intentionally. Omw to see what I can help with today...thanks, the tech does appreciate this thread!

Def check the transistors next. Though that one looks odd at Q50, i think Q52 is the transistor that drives that column. The schematic is hard to follow though, so maybe I'm wrong on that one.

In any case, this is what I'd try next--here's what Clay's guide for data east repairs recommends:

Testing the Switch Columns (drive)

To test the switch columns, do the following:
Remove the backglass.
Turn the game on.
After the game boots, go to the diagnostic menu's switch levels or "TST" test.
Unplug the connectors at CN8 and CN10 (bottom portion of the CPU board).
Connect an alligator test lead to pin 9 of CN10. Pin 9 is the left most pin, as facing the board.
On the other end of the alligator test lead, clip on a 1N4004 diode, with the banded end away from the alligator lead. Touch the banded end of the diode to pin 1 of CN8 (pin 1 is the right most pin, as facing the board).
The display should show switch 1 is closed.
Move the diode/alligator lead on CN8 to the next pin. The display should show switch 9 is closed.
Repeat the previous step, until pin 9 of CN8 is reached. Switches 1, 9, 17, 25, 33, 41, 49, 57 should be closed on the display as the lead is moved forward, pin 1 to pin 9, on connector CN8. Note pin 6 is a key pin, and should be skipped.
If a particular column number does not display as closed, or is closed without any test lead connection, there is a problem on the CPU board. Usually this is a bad switch matrix column 2N3904 transistor at Q48-Q55.

you can test transitors https://pinwiki.com/wiki/index.php?title=General#Testing_a_Transistor.2C_Silicon_Controlled_Rectifier_.28SCR.29_or_Field_Effect_Transistor_.28FET.29

no sense replacing them if they are good

Looks like that board has been through a bit of stress... I'll be honest, if you aren't prepared to get into some potentially involved repair work, you may want to opt for a replacement CPU. I can't speak to the quality of rottendog Data East boards, and you may also want to consider having the board repaired professionally if it isn't too far gone. There's a number of reputable techs here on pinside and elsewhere online that may be able to fix the board for you if you opt to try that route.

In any case, it's pretty safe to say you identified the problem as being board-related.

Edit: looks like that's a different section of the board that had gotten toasted. Those transistors are for the special solenoids (pop bumpers, slingshots, etc)... Definitely looks like the area has been repaired. Did you guys find any bad transistors for the switch column drivers?

If you get a new board buy it from someone who can burn the ROMs and change the jumper for you.

I put in an RD in a laser war last month and it worked great. But I also have a rom burner

that rom will work if you change the jumper

I would test the switches on the line before throwing a $400 board at it. Might just be a bad diode on a switch.

this board looks pretty jacked and hacked. The last pic you shared is the switched solenoid section and has nothing to do with your switch matrix so repairs there will do nothing about the red saucer. Here are the parts that look hacked in that last pic

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C47 which looks to be exploded on your board is part of the display circuitry? see here: pasted_image (resized).png

meanwhile I see stuff like this and I don't trust this board:
pasted_image (resized).png

If its working, isolate the switch problem first.

Would be unfortunate to spend $400 for a board, still not fix the problem which turns out to be a .20 cent diode.

Diode failing is common enough I keep 50+ on hand and just replace even if I think one is bad. Not uncommon for them to fail at all.

if you know someone that can do quality board work have them look at it. If you don't feel comfortable then replace it

a missing switch diode won't cause any damage but prevents the column from passing on to downstream switches. you do need a diode there

EDIT: there is a diode there. It's under the rubber insulator

Make sure there isn't a diode on the underside of the playfield, DE did that over the years.

No dmd on laser war. Are your displays not working?

make sure and check you jumper location. I believe it has to be at J4 even though you'll only have 1 rom in that game

pasted_image (resized).png

did you add J4? removing J5 is not enough

if coils are getting hot it's because they are locking on. Do you hear a coil engage when the machine turns on?