I'm looking for some guidance here - have a Lethal Weapon 3 that was working, came back a week later, it's dead.

Power-on, garbage on DMD.

Looked inside backbox, reconnected plugs on the PSU board, still the same - closer examination of the Playfield Power Board - and I saw a very crispy resistor (220 ohm, 1/4 watt) @ R17.

All TIP36c transistors from heatsink to ground strap had continuity.

Pulled the Playfield Power Board (PPB), examined the diode in that circuit, once desoldered, and the diode @ D19 (1N4004) tested fine. Hooked this diode up to my semiconductor tester and it looked to be a little worn out but not bad.

Pulled the TIP36C @ Q3 and it was deader than a doornail. Failed semiconductor tester altogether.

I see that this circuit has J8-7 listed as output, and J8-6 listed as input.

Looking at the LW3 tech chart, it shows that J8-7 on the PPB is connected to coil 22, "Laser Kick", and does show Q3 on the PPB (the TIP36C that was toast) and Q13 on the CPU board.

I need to get back to the machine to test Q13 (TIP 122), but I'm a little confused.

My gut tells me that this resistor & Q3 got roached by a locked-on coil.

The only fuse I found blown was the 7A (250V, SB) on the PSU board (NOT PPB), and the coil looks to draw 50V (per CPU schematic and Tech Chart), which leads me to believe that if the coil were locked-on, it would pop fuse 5 on the PPB (5A, 250V, SB).

I'm getting lost here - I'm ok with pulling parts and component testing, but I'm not seeing the logical path as to why F2 on the PSU board cooked, and why F5 on the PPB did not.

Data_East_CPU_520-5003-03-SHEET-3-of-4.pdf

Data_East_Lethal_Weapon_3_Tech_Chart.pdf

Data_East_Playfield_Power_Board_520-5021-00-Reduced.pdf

PPB section Q3 (resized).png

PSU section Q13 (resized).png

So - turns out the "Laser kick" solenoid was burned up, locked on, and also the bridge rectifier on the PSU was toast. In case there are others out there with similar issues. What came first? Probably the bad bridge rectifier.

Replace your BR or PSU on DE games is my advice to anyone having trouble with theirs like I did.

http://www.pinrepair.com/sys3/

Not exactly what you need perhaps - but this does show you how to test MosFETs.

Sorry - this notification didn't pick up like I would have expected it would. I did replace the power supply on mine and the kickback coil, and I did do work on the driver board. Good luck! Mahoyvan