Did you adjust the switch with game power on?
Did you see sparks? Smoke?

Is the coil firing and staying held ?

Probably blown the transistor for the pop bumper, sorry I don’t know which one it is

Maybe reach out to Fred Swemmer as he can probably tell you exactly how to repair the board.
[email protected]

-Mike

Does the coil fire in test mode? I would venture to guess you ran coil voltage through the special switch section. See: https://www.pinwiki.com/wiki/index.php/Williams_System_3_-_7#Special_Solenoids

Also: http://firepowerpinball.com/wordpress/physical-layout/driver-layout

The heat is a pretty big clue something may be wrong with the chip. Hard to tell from the photo, but looks like a 74HCT06 or 08. You can do a quick test as per this procedure...

https://www.pinwiki.com/wiki/index.php?title=General#Testing_an_integrated_circuit

Very common and inexpensive to acquire.

Accidentally sending high voltage from the playfield back into the MPU is something that has happened to me. Typically logic chips on the MPU such as your 74xx are the first thing to take the hit. The chip gets fried and passes most of the current to ground. Let's hope that's all it is, and that it did not blow out any of the more expensive chips.

You aren't necessarily going to see sparks or smoke. Sparks and smoke require a lot of current. This happens too fast; the chip(s) get blown out before any substantial current can pass... after all, you can blow a logic chip with static, which has an extremely tiny amount of current.

Multiple chips could be involved - and if you created another fault elsewhere, you may have instantly blown out your replacement chip.

You're going to need to examine your schematic. Trace back the path from where you think you shorted it out. When I blew my switch matrix, I knocked out a 7432 along with a 7400... luckily they stopped it because the next chip was a RIOT. Looking at the schematic, it was obvious which chips were involved and which gates on those chips were blown.

Well that sucks.
-Mike

That's really disheartening. Does Mr. Swemmer at least provide schematics of his builds?

I've never seen any and have searched but never asked Fred either.
-Mike

No wonder so many pinball vendors come and go.

That's good to know. At least that is something.

As far as learning. Learn by doing. You can match components to the drawing to see how things are connected. Also, review PinWiki throroughtly... it will help you with the overall concepts so understanding schematics should be easier.

I guess I need to learn to match images better.

williams.jpgswemmer.jpg

I think FETs are being used as there are no 2N4401 pre-driver transistors (not necessary when using FETs).

Well, let’s assume he used the same numbering as Williams since the parts placement looks the same. The chip you are pointing at is a 7408 AND gate chip. There are several on the driver board. Part of IC7 is the Special Switch input for Solenoid 21 and 22.

Check the switches you were adjusting and make sure they are not shorting to coil power or metal somewhere.

Try disconnecting J13 from the driver board and see if IC7 still gets hot.

If it still gets hot, turn off the power, remove IC7 and install the chip from IC6 into IC7s spot and test again. Be careful not to bend any pins removing and installing.

If the “new” chip doesn’t get hot, reinstall J12 and test if it now gets hot.

If it still is ok, test the pop bumpers.

I suspect the chips they use are 74HCT08 - pretty much the only version of this chip you can still buy new. It should be available at any well stocked electronics store. Even Amazon has them - not the best price but it is convenient.

Juried Engineering Fairchild MM74HCT08N 74HCT08N 74HCT08 - Quad 2-Input and Gate (Pack of 5) https://a.co/d/3iIGZU5

Hold on - I just looked at the BK schematics and solenoid 21 and 22 are not used. This chip getting hot can’t be the reason the pop isn’t working. Unless the numbering is wrong on that board.

The pop is on Solenoid 19 which comes through IC6 (right below the hot chip). Maybe the numbering is swapped on that board, idk. In any event, I’d suspect IC6 or IC7 as the first things to check

Maybe try swapping the chips in IC6 and IC7 and see if the problem moves.

You must have a short up or down stream from those chips

IC6 and IC7 feed into IC8 and IC9 (which are different chips so don't mix them up). You can try removing IC8 and IC9 and see if IC6 and IC7 still get hot.

Also, when you say hot, how hot are they getting? Can you keep your finger on them?

I'd get out the multimeter and pull one of the ics that is getting hot, and see which of the pins show low/no resistance relative to ground. Then follow that downstream/upstream and check against data sheet for that ic, etc. (Note that at least one pin on ic that is running hot will show as ground -- check against data sheet on ic that's getting hot to see which pin(s) are expected to be connected to ground.)

Congratulations on figuring that out! I never noticed their orientation is reversed. They are that way on the original boards too

Did those chips still work afterwards?