So I have been trying to troubleshoot my lw3. My vuk is energized as soon as I power up machine. I have checked the pre drive and drive transistor for the Circuit. Q2 was blown and when I replace it it blows still. I also changed the coil and diode. What else could b causing this?

There is a pre transistor on the PPB Board also?

All those transistors test good. Anything else?

Ok how would I check 7406? My skills r limited.

Yes I have been testing with a damn. I have learned how to test transistors. Checking ohm measurements btw legs. I just meant I was limited to the troubleshooting I have done already. Need help with further troubleshooting.

Damn meant dmm. Lol

K I finally had some time to try your ideas out. So I bench tested all transistors, resistors and diodes that we’re mentioned above. I replaced the burned transistors q5 and q3 that I stole to test at q2. I removed the purple yellow wire from the vuk coil. I unplugged cn12 and clipped my red lead on cn12-8 and ground clip on he ground terminal on board. Upon power up I burned q3? Which is for laser kick? Now the problem is even more compicated! Lol. I replaced it again. Transistor was installed with writing up same as others. I only have two more transistors that r new and the one on the board still tests good. I shut off immediately soon as I scene it lighting up. I have to walk away now as frustration has overtaken. I also unplugged the purple yellow wire from the laser kick coil. Still I lights up. Please help

I have already removed the purple and yellow wire from laser kick coil. And it still lights up q3? So I can’t power up the machine.

K my bad I only clipped one of the two purple and yellow wires. I just clipped the other. Machine boots up now with out smoke. Lol. Will test now. 12-8

K here’s a update. With can 12 disconnected I have my red lead clipped on pin 8 and my black lead clipped to ground terminal on board. When I go into test mode and fire vuk coil nothing changed on meter... no voltage. I did notice something. When I was cycling through diagnostics meme. Cycling flashers.. cycled my coils all at the same time but no flashers? When I go into coil test mode. Some of the coil tests r firing two coils at a time? None of my flashers r working

Yes I should have disclosed this to begin with. I bought the machine in rough shape. There was also battery leakage from the batteries. The machine would not boot. I removed the batteries and cleaned the holster. Installed new and machine booted and played functional. I was missing the mars light and the knocker coil. So I ordered shop out parts. Replaced rubbers, lights, burnt connectors on the gi, ordered a beacon from amazon and replaced knocker coil. Upon boot up the mars beacon continuously lit. So I reclaced the drive transistor. But the traces for the transistor on the board where damaged so I ya to hack a couple of traces. I had to jump the ground leg to the drive transistor leg next to it. Not the vuk transistor the other(got no print right now). I didn’t think this would b a issue because all the transistors shared that ground leg? That’s when I booted the machine and smoked the vuk coil. I tested for continuity btw transistors and none was present. All transistors tested the same. I will record which coils r firing together tmrw when I can get back to it.

K here’s a update on the coils firing.
In cycling flashers mode trough, both drop targets and all outholes continuously cycle at the same time... no flashers. During cycling coils mode
#1l fires outhole
#1r fires outhole
#2l nothing
2r nothing
3l nothing
3r nothing
4l left outhole
4R left outhole
5l right outhole
5r right outhole
6l center drop target
6r center drop target
7l right drop target
7r right drop target
8l knocker nothing(coil disconnected)
8r nothing
9 nothing
11 gi flashes
12 nothing
13 nothing
14 nothing(disconnected)
15 nothing(coil disconnected)
16 nothing
17 left bumper
18 center bumper
19 right bumper
20 left along
21 right sling
22 nothing (coil disconnected)

None of my flashers work during test

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Bump

Ok have tested the method above. With my alligator on the metal tab of q29 and the other end grounded the relay is opening and closing only some of the times that I ground it. I tested q29 and the pre transistor and both test good. Is the relay sticking? Or is it the signal that is not telling it to open/close?

Ok so I resoldered all the pins for the relay on the ppb board. Now when i test with alligator clips the relay does open(clicks) everytime I ground q29. So I tried to connect my laser kick coil. Powered up and it’s burning away at q3 still(transistor was bad before I tested already) does that matter? Only have a couple transistors left. So I diconnected the coil again. I tried to connect my vuk coil again to. Upon power up it still locks up. I noticed All the metal tabs for the 5 transistors q1-q5 on the ppb board short to ground. Is this normal? Games is cycling flashers properly now

I also noticed when I unplug cn12-8 the flashers stop working during “flasher test” it only runs actuating coils.

How would I go about testing the 7406 at 1J?

No not sure at all. I was just referencing a previous post in the thread.

I checked all 4 of the 7408 chips above the drive transistors. All the test points read around .160v dc

Appreciate the description. I found the correct legs for the vuk. One leg has a 5vdc supply. The other two when coil is pulsed through coil test maxes out at .8vdc. I found the correct legs for a working coil and it was reading almost 5vdc when pulsed. Does that mean my 7408 needs to b replaced? That would cause my coil to b locked on? Thought it just wouldn’t cycle?

K before I check that I just ran my coil test and i have multiple problems. Here r the results of my test.

Coil test
1l outhole...nothing
1r flash.... working
2l trough eject.... nothing
2r 3 panel flash.... nothing.
3l not used..... nothing
3r flash... working
4l left saucer... working
4r flash.... working
5l right saucer..... working
5r flash... working
6l center drop target.... working
6r flash... working
7l right drop target... working
7r flash.... working
8l knocker.... disconnected
8r flash... working
9 flash... working
11 gi.... working
12 ball launch... working
13 coil not used
14 mars..... disconnected
15 vuk..... disconnected (coil locks on when connected)
16 flash.... nothing
17 left bumper... working
18 center bumper... working
19 right bumper... working
20 left sling... working
21 right sling.... working
22 laser kick... disconnected(when connected burns q3 on ppb board)

I can hear the r/l clicking but maybe it’s not working? Maybe it is related to those transistors u have mentioned ? But I have removed the board and tested as per pinwiki repair guide and they test ok. And wouldn’t only c the same coils not firing if those transistors whet a issue? Plus I have the problems with coils 16, and 22. Is there a component that shares all these collectively?

It’s def the same coils cycled it a few times over. Started off with just vuk. Then it was laserkick. Then trough eject... outhole... flashers. it seems everytime time I remove the boards and reinstall I lose more coils.

Ok thanx again wayout440. Ur knowledge patience is greatly appreciated. Will get back to the machine later today.

Ok so I got back to the machine. I fixed some of the coils that were not working(cracked solder joints on ppb board). Back to troubleshooting the vuk locked on. When pulsing the 7408 chip for vuk I’m not gettin enough voltage on the two legs. It stays under 1v. I tested another working coil and when pulsed the other legs read highs of almost 5dc and the other round 3vdc. Does this mean my 7408 chip is bad and needs replacement? Causing my coil to be locked on??

I have also noticed that my coil voltages are reading higher then stated. My coil that are listed at 32vdc are running at 45vdc and my 50vdc coils are running at 84 vdc. Is this also a problem? The coils that are working are working with those voltages.

Back at it. I tested my 7408 again and it’s def not supplying enough voltage for the vuk. Under 1v are I’m reading for the logic high/low legs. U also told me to test the ra7 pull up resistor? It think it’s r9 and I isn’t downstream from my voltage problem ?

I checked ra9. Tests good. I’m gonna order a 7408 chip if no one else has other ideas?

Replaced my 7408 chip. Still not gettin enough voltage on my high/low inputs for the vuk gate?

So back at it again. I replaced the 5f 6821 pia. But while I was desoldering the old chip I burnt away the trace points for pin 38 and pin 2. I can’t c the traces on the board to c where they go? Can someone please tell me what points they go to from there. I am unable to read the print. Now upon start up my machine does not boot properly.

K I jumped that along with a couple others that had no continuity. I was able to understand the numbering and trace the rest. But is pin23(cs2) run? That’s the only trace I can’t can’t read where it goes?

Sorry and pin 19..... ugh.

K both those were good. But now my machine boots up and 5v and pia light stay lit. Does not boot. I placed a jumper btw pin 38 5f and pin 38 11d also. Is this correct? So pins 37 and 38 have continuity on both chips? Irqa and irqb.

Those points all test good. I have checked all points btw both pias and there good. What would cause my machine not to boot? Only the 5v and pia leds stay solid on boot up? Apreciate all the help. Maybe I should order a new rottendog mpu board? Damn it didnt wanna shell out the price of a new board.

The machine booted properly before the replacement of 5f pia

So one last attempt. Can someone please tell me what pins on the 5f 6821 chip that are not directly on that numbered print where they are coming from or goin? I’m not grasping how to read 1-12f e line?(though it would mean print 1.... 12f location on that print?) all similar pins that read like that to. If this fails I’m gonna buy a new rottendog mpu

K I was able to read most of it. Thanx for the detailed description. Just two pins I can’t read. Reset pin 34. I don’t c any reference to “reset” at 1-12a? And pin r/w pin 21. 1-12g?

I think I figured it out. Pin 34 goes to r106? Listed as 1 12f and it supposed to b 1-12a? And pin 21 r/w goes to 6d pin 18?

Ok all pins test good for continuity. When I boot my machine my gi lights up. Maggie calls out “back in action” then nothin. Only the pia and the 5v lights come on and stay on. No blanking led. Reading the pinwiki guide it states the eprom at 5c is bad? I did have battery leakage when I bought the machine. I cleaned it up but never neutralized. Could the damage from the battery leakage b time delayed? Should I try and order a new eprom?

Here r some pics of my board. I don’t c any corrosion ? I also noticed my eprom chip doesn’t have a sticker covering the lens? Does that matter? It hasn’t had one since I picked the machine up 6 months ago.

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Update! My machine is working now. Installed a new rottendog mpu board. Fixed my locked vuk. But still had some other issues. Found the solder flux I was using must b conductive? After cleaning away the leftover flux with alcohol and carbon deposits from board burning its playing flawless now. Expensive lesson learned.... ouch. Thanx for app the advice in the post.