Hi all.

I've been working on a Road Kings for months now. I'll give a rundown of what I've done and what the most recent issue is.

So this Road Kings initially stopped lowering its ramp. I wound up replacing the power board and the ramp started working again.
Shortly after, the left flipper stopped working. It was blowing the main flipper power fuse. It would blow the fuse after a couple of days each time I replaced it, so I got a new flipper control board for it, the small one and I rebuilt the left and right flippers and put in new solenoids. After this, it was blowing fuse... F4 I think it was every time I tried to test the left flipper.

I had just replaced the solenoids so I started working on power. I tried replacing both of the bridge rectifiers. That didn't work so I looked at the game board. I put in a new relay for the flippers and reworked some cold solder joints on the game board. I plugged that all back in and tested left flipper, blew the fuse again.

I then swapped the solenoids, and the issue followed the solenoid. Now the right flipper was bad, so I replaced that solenoid and now both flippers work.

However while testing these 2 flippers I saw smoke coming from under the playfield. And now I'm totally lost on what the issue could be. here's the new details:

the Left and Right pop bumper solenoids both burned up. Like totally smoking hot. There is an individual fuse that power routes through in the upper box, it then goes to the flipper power supply. This fuse blew and stopped the power going to the pop bumpers. The flippers still work. The ramp is stuck up again. I tried rewiring the ramp solenoid but it won't pull the ramp down. The pop bumper solenoids still won't fire.

What could be causing this new issue? does anyone have any advice? I'm about at my wits end with this machine.

Thanks for reading.

I'm worried I may have attached the 2 wires on the bottom left of the main board backwards. I'll have to check those two.

Originally, the game played fine except for the ramp sticking up on occasion. Everything appears to be wired correctly, I don't see any weird wiring or anything. Back before I pulled the game board, one time when I was testing the left flipper it pulled enough power that the house lights dimmed just before the fuse turned bright orange then blew (F4).

All parts appear correct and the fuses are all the correct amp/voltage per the in cabinet labels.

The pop bumpers definitely did not have any issues before. Both the left and right pop bumper solenoids burned up. I could see the smoke from both of them.

I'll have to look at the switches and see if any are shorting. I don't often have time to look at this one, so I'll update when I can.

Ok I'll check those, thanks! Is there a way to check them in circuit or do I have to pull them from the board?

Hello again. I’ve finally had a chance to test transistors on this mainboard. Unfortunately I don’t see any TIP102 transistors.

Thanks wayout440 for the lead and thank you everyone who has chimes in

Most transistors on this board are 2N6532 transistors. This includes bank Q80-Q87, odds from Q69 to Q79, and the 2 long banks Q6-9, Q22-25, Q14-17, Q30-33.

One row of transistors in the board are TIP42. This is even numbers from Q52-66

The bank of TIP42 are all showing either 3.67, 4.72, or 5.73 ohms resistance. If I put it on diode/beep mode none of them beep and all show .8xx. None of the 2N6532 transistors on bank Q80-87!show anything other than .0L in both modes.

The rest of the 2N6532 resistors on all banks will give a short beep in indicator mode, and the value dances around and sometimes gives another short beep. in resistance mode some show in the 200-700 ohm range, some show in the 25 MOhm range, and some show 0 ohms.

Should I just throw new transistors at the whole board? Might be cheaper than burning my time up. What would I replace the 2 types with?

Are there any other parts I may want to throw at it?

Thanks in advance y’all have been a huge help

Thank you so much! yes it was to the backbox ground for all the transistor testing I did. I do have the board out so upgrading the transistors will be my next step.

There definitely are multiple transistors (3 in different banks IIRC) that are shorted out. Just to verify, both the TIP42 and the 2N6532 transistors can be replaced with the TIP102?

Thank you yet again for all the help.