Hi Gary did you test that coil in coil test to see if it fires?Is that coil locking on when you power up the game?

Here’s another way to test transistor
To test transistor power off the game set meter to continuity,Place black probe onto ground(grey metal strap).With red probe touch the tab of transistor,If you hear a beep from meter that means transistor is bad/shorted

How about traces on the circuit board ? From transistor leg, up towards the transistor body not the solder point, to another solder spot away from the repair area ?

I had a LOTR blowing a flipper transistor and found a cracked trace causing an instant blow out.

LTG : )

The diode — what do you mean by ‘same order’ as other sling? Band Side of diode is towards the high voltage lug/wire, yeah? (assuming transistors ground the coil when fired). Even if incorrectly orientated it shouldn’t short until the sling fired but just checking.

You can’t get much out of testing resistance of legs on a transistor other than that if you get a closed o resistance circuit between any of the 3 legs when its isolated from a circuit it’s toast.

Does sound like it could be a board short.. weird the fuse isn’t blowing though — if you had a high voltage short to ground on a board I’d expect the short still present with transistor removed from circuit and the fuse should be blowing...

If u blow the transistor you can tell easily just by testing continuity between legs of the transistor. If any legs are shorted together it’s blown. The leftmost leg is usually the gate (which is the trigger on the switch, essentially). The other 2 legs allow the circuit to complete. The gate shouldn’t be tied to the other legs, and the legs shouldn’t be tied together unless the gate is triggered.

Look at the above post#3 about transistor

No— a transistor is almost always good or bad. If it’s good - you won’t see continuity when you use your MM and put a probe on one leg of the transistor and the other probe on another leg. If it’s bad, the transistor shorts internally — the semiconductor inside becomes damaged and it will short closed (internally) between the at least some of the legs..

Ohm readings on the transistor isn’t telling you much, esp. when it’s part of a circuit.

For BJT transistors ... this is not true (in my experience). A "bad" reading always means the transistor will not function correctly. A "good" reading does not mean the transistor will function correctly. In others you may get false positive measurements.

For FET transistors ... I don't have much experience but the experience I've had indicates the same as BJT. I've measured transistors as "good" but they don't work because when replaced with another new ("good") transistor the problem gets fixed.

Make sure the coin door is closed if there is a high voltage interlock switch installed.

The board can almost certainly be fixed. If you're not experienced enough you can send it off to board repair person. There are a few reputable repair people on this site.

If you decide to replace the board I believe you want Rottendog SDB004. You can confirm this for yourself by visiting http://rottendog.us/sdb004.html to make sure.

Ripley's has a high power lockout switch on the coin door. If you're in diagnostics, the coin door is open and high power (both 50v and 20v) is disabled. If you push in the switch, which is near the door hinge, led 201 will light.

You need to determine if your problem is on the board or somewhere else. With *power off*, remove connector J3 from the driver board. Test continuity (diode mode on meter) between pin 3 on the female side of the connector and ground. You can use one of the board screws for ground. If you get continuity (meter buzzes), your problem is in the wiring or playfield. If the meter doesn't buzz, test pin 3 on the board to ground. If that buzzes, your problem is on the board. Pin 1 on connector J3 should be labeled on the board.

The coil charts in the manual shows that Q18 connects to connector J3 pin 3. The coin door schematic in the manual shows the high power lockout switch. Narrow down your problem. At worst, you may need someone to repair your board, but you likely don't need a new one.

J7 pin 3 supplies power to the right sling. J3 pin 3 is the ground connection for the right sling. As I mentioned, this is shown in the coil charts in the manual.

If you removed J3 and pin 3 has continuity with ground, you have a problem with the 20 volt circuit on the board. Bridge rectifier 2 supplies power to the 20 volt circuit. Test the bridge using the procedure linked below.

https://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Using_a_Multimeter_to_Test_the_Bridge_Rectifier_and_Capacitors

Don't worry about led 201 just yet. Narrow down your 20 volt problem first. Led 201 could just be bad, but first things first.

My mistake. J7 pin 3 completes the ground side of the right sling circuit. J7 pin 1 supplies power to the right sling. You can see this on page 101 of the manual as well as in the coil charts.

If J7 pin 3 shows continuity with ground, Q18 or something else in that circuit is bad. If you've already replaced Q18 and the replacement is testing good, I would recommend sending the board out for repair. Testing the other components in that circuit sometimes requires removing them from the circuit by unsoldering one side. I use and recommend Rob Anthony for board repair. Rob can also test your 50 volt circuit. Lockwhenlit.com

You said you already replaced Q18. Did it test bad or did you just shotgun it assuming the transistor is bad?

You need to test Q18. If it tests good (like the others near it) and J7 pin 3 is still showing continuity to ground, a resistor or something else in the circuit is bad.

You can check for shorts on the playfield by testing the female side of J7 pin 3 to ground. If it buzzes, you have a short somewhere in the wiring or playfield. I suspect your problem is on the board rather than elsewhere.