Alrighty! So I'm almost finished reviving an old Scorpion pin. The last big issue I need to tackle is with the pop bumpers which suddenly went haywire. Scorpion has 3 pop bumpers and the bottom one works fine. The right one will lock on when I either try to start a game or when i enter solenoid test mode. The top bumper will start and stay on as soon as i power up the machine. They were all functioning properly a few days ago so the wiring should be correct. I tried re soldering the wires and testing the diode and everything looks fine. I have to turn off the game as soon as I start it now or else I keep blowing the F2 fuse(solenoid).

Using a DMM I probed the blue-brown wire for the top bumper (should be connected to the driver board 2j12) and it is grounded all the time. I dont think that's right? I thought bumpers were supposed to be on all the time and fire(short) whenever the switch is activated. I looked at the switch and it is open so I don't know why the blue-brown wire is grounded.

On the right bumper I have no idea why it locks on during the solenoid test (right as it enters test mode) or whenever a new game is started. I haven't probed yet but I can assume it has the same issue with it's driver wire where it shorts the wire when the game starts and doesn't wait for the switch. Are pop bumpers special solenoids and function without waiting for the driver board?

Also it should be noted that in order to get the game up and running properly I swapped the MPU and Driver board with a rottendog MPU327-4 combo so the wiring is slightly different from a stock board.

As of right now my only inclination is that something is wrong at the actual bumpers but I can't see it. Ive been looking for maybe some stray solder that is bridging some connections or a loose cable but I'm losing my mind over this. Do you think I maybe blew a transistor on the new board or are one of the IC's acting up? What would I look for with a logic probe?

Thanks for any help!

PS: Is there a site that has manual/schematic information for pins? I have a couple old/original/cool diagrams and information about Scorpion that I haven't seen online and I'd be happy to share.

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I checked the 2j12 connection linked with the
top bumper and the pin is grounded while powered off. I don't know much about transistors and ics but does that sound like the tip 120 transistor is bad and needs replacing?

Edit: after testing the transistor I saw it was shorting all the legs so I swapped it and now one of the bumpers works. Woo! I looked at the board a bit more and ic5 (sn74hct02n) looks a bit faded which is weird for a brand new board so that's probably why the bumper is engaging. I don't know how it connects from the rotten dog schematics but that's probably going to be my next step

The Q2 transistor was shorted so I swapped it with another similar one in the toolbox. That fixed the 'stays on when the game powers on' bumper but the other one still sticks during the solenoid test mode. I checked the leaf switch and it is set up correct. I'm thinking it has to be further inwards in the circuit. I've noticed 2 other lights dont work properly during attract mode but they do work fine in game. The Light test (02) has them light up as well. I'm going to wait for an answer from the rottendog guys on the IC5 that looks off and maybe see if that chip is controlling the bumper somehow.

Edit:

Did some more probing. Pin 3 on 2j13 is linked with the bad bumper and the q6 transistor. When I power on the game, nothing is off. When I start a game or enter solenoid test mode, pin 3 instantly shorts itself. I don't think that means the transistor is bad since it is functioning as a switch albeit incorrectly. I followed the bottom pin of the n-type MOSFET (Q6) and it goes directly to ground. The top pin goes through a resistor, then to ic9, and then I believe to sip11 pin 3 from the left. The other pop bumpers are receiving a pulse ground but this one is stuck open giving 5v

I don't know what to do with this Informatiom but I've gotten that far.

Just got an email from rottendog. They sent me the full schematics and said they would check the processor chips or the 62256 ram chip. I don't know which chip the ram chip is and what should I be looking for in the processor chips?

I've noticed the 5x and 30,000 special lamps don't work properly during attract mode

MPU327-4 PAGE1.pdf

MPU327-4 PAGE2.pdf

I appreciate the advice. I could just buy replacement chips and see if they fix the problem but I was hoping someone could give me an idea of what to probe with my logic probe. Would there be a way to make it so the bumper worked but didn't score? Like bypass the driver board. Could I wire one of the switch contacts to ground and so whenever The ball hits a bumper it'll fire?

Luckily they aren't smds haha. I don't worry about through hole

I tested the voltages coming from ic8 and ic9 linked to the bumper. ic8 is giving me .638v on pin 12 which is connected to the bad bumper. Can someone help me understand how the voltage gets to that pin? What is the function of SIP6? Does it give a signal or is it supposed to add 4.7k ohms of resistance to effectively ground the signal? I'm learning a lot about electronics but I still have a ways to go. If a pin on that SIP is giving a low reading, does that mean the resistor is bad or am I looking at this backwards?

Ic8 is an AND gate so pins 12 and 13 need to be 1 for pin 11 to be 1. if pin 11 is 1 then it doesn't fire. if pin 11 is 0 then it fires. Currently pin 12 is .6v so basically 0 and that causes it to fire as soon as i start the game?

20220318_175955 (resized).jpgbad sip (resized).png