I need some help as I’ve stared at the schematics till I’m blue in the face on this game. I have been going through this Pinbot that I bought off of eBay (won’t make that mistake again lol) and I keep running into issues. When I picked up the game it worked, but was hacked up and filthy. I shopped the game completely (it actually is a pretty nice game it’s just driving me nuts). When I hooked it all back up after the shop out the special solenoids locked on and blow the fuse. On top of the the flipper are active at all times. So with no game started they will fire when you press the button. Furthermore an entire row of lamps were locked on as well. I have shopped tons of games but still thought I may have been careless so I checked back through all the wires of the effected systems and saw nothing.

The game had some acid damage that had been “repaired” by the previous owner. I thought this could be the issue so I actually repaired it by removing all parts, sanded, neutralized, cleaned and repopulated all effected areas.

So now I’m kind of looking for the next step. I figured I’d start a thread here and see what people thought. I always seem to overlook something simple. Thank for the help in advance

Adding some pictures of the mpu. The whole board and the repaired areas

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I am hoping I can fix it. Should be something simple and I’m just missing it I believe. Might even still be in the playfield where I shopped it

On a related note. I tested all the special solenoids coils today and they all read between 3.8-4.2 ohm. I didn’t think a bad coil would cause them all to lock on but I thought I’d rule that out anyway lol

Still looking for any leads if any of you have any.

It’s all 6. Both slings, all three pop bumpers, and the left side 1251 flasher of the face.

Ok so I have a logic probe but I am not really sure how it all works. What do I do to check u49

I did get under the chips as well. I added sockets and replaced all the visibly affected chips.

I have a circuit breaker to save fuses but I will pull those plugs also.

Ok I got the following

Pin 1 nothing
2 nothing
3 low
4 low
5 high
6 high
7 low
8-14 high

I had 1j18 and 1j19 unplugged when testing

So what should the next step be

So I think I’m doing this right but I’m by no means a genius at this stuff. I have the schematic and by the looks of it these are the places those signals come from? Please correct me if I’m wrong

u54 pin 39 is high and pin 19 has no reading

U38 pin 19 is high and pin 39 is high

I’m not sure but looks like the other signal comes from sr19? Pin 4 is low Pin 7 is high

That makes sense now lol.

U41 pin 19 is high and 39 is low

Thanks for pointing that out. I had no idea. I’ll order some new ones

I will start checking the traces and the solder job. I’m assuming it is the traces and not the chips as the same problem was occurring before I rebuilt this section. However, since Ed pointed out the chips are counterfeit I’m just going to replace them anyways to be safe

I read all of that and I’m a little confused. The parts I ordered for SRC1-5 and 7 were the parts listed in the manual. I ordered them from either Great Plains or mouser.

I will order those too thanks

I ordered the src that you linked. The special solenoids locked before I rebuilt the battery damaged sections. Could these be the culprits to it continuing since I used the wrong ones?

I checked the solder on the sockets and all seems well. I am in the process of checking all the traces. The solenoids locked on before I replaced the 6821 chips. I know Ed mentioned they are counterfeit and I plan on replacing them anyway but since it was doing the same thing with the old chips I’m guessing the problem is more than likely in the traces?

There is a blown out trace from pin 9 on sr20 to to zr8. It looked like the remnants of the trace were laying directly across the other legs of the resistor pack

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Any one know a source to buy legit 6821 chips.

So on this do I need to simply replace the zener diode and resistor pack and jump the broken trace or are there other parts that I need to check

I have pulled the SRC 1-5 and 7 from the board and ordered the proper components from Great Plains. Can I test this without those installed? I don’t care to wait for them to come in it will just be a few days before they do.

I got ya. I need to order that zener diode. I’ll get that ordered and put it all back together and test. It may be a couple of days before all the parts come in. I really do appreciate all the help

Ok, I will go ahead and remove the zener and repair the trace and then test the board to see if all special solenoids still lock. I have that 4.7k ohm resistor pack. Would it be best to just go ahead and replace it while I’m working there to be safe?

Ok so I removed zr8 and replaced sr20. I repaired the trace with a jumper. The special solenoids all still lock on. With the exception of the right sling which I assume won’t lock without zr8 installed. So is it safe to assume my next step is to replace all the 6821s?

Zr3, zr4, and zr5 test at 4.5k ohm

Zr6 tests at 12.3 ohm

Zr7 tests at 2.9k ohm

With one leg removed they both test at approximately 180k ohm

I was just checking some continuity of the pins on 1j18 and 1j19. I am getting continuity between pin 8 on 1j18 and ground. Pins 6,7, and 8 all show continuity and I think only 6 and 7 should. Is that correct

I have replaced the SRC 1-5 and 7 with the suggested part. I also went ahead and replaced the zener diodes in question. I still have continuity to ground on 1j18 pin 8. I don’t really know what to do next. I haven’t put the board back in the game considering that pin is shorting.