Did you replace the pre-driver transistor?

Do you have a logic probe?

Pull the solenoid fuse so the coil does not energize.

Power up the game and connect your logic probe.

Probe the AND gate that drives the Ball Release solenoid.

IC1 pin 9 is blanking input (should be HI if all is well)
IC1 pin 10 is the input from the PIA and it should be LOW when the solenoid should be off and flicks HI when the solenoid is activated (you can use solenoid test to activate it if you want)
IC1 pin 8 is the output - it should be LOW when the solenoid is off and HI when it is on.

If IC1 pin 8 is reading low, and the coil is still locking on, you have a bad pre-driver transistor or a bad driver transistor or both. (most likely the cause)

If IC1 pin 8 is reading HI when IC1 pin 10 is LOW - IC1 is bad. (less common)

If IC1 pin 10 (PIA input) is locked HI - you have a bad PIA (rare)

You could also test for a wiring problem by removing J11 and seeing if the coil still locks on. If it still locks on with J11 removed, look for short in the wiring between the driver board and the coil (wire pinched, coil terminal shorting to metal, etc)

That doesn't sound right. Can you check the AND gate of the next solenoid? Pins 12 and 13 are the inputs and 11 is the output.

Both 9 and 13 should be solid HI when all is working. If they are pulsing, something is very wrong.

Pin 8 being HI will fire that solenoid. Now its just a question of what is causing it to lock HI when it shouldn't. Could be bad IC1 or something further up the line.

Is the 40 pin interboard connector original?

did you try replacing the pre-driver?

Does the board have AMI branded PIA chips?

Firepower will refuse to start a game, or work correctly without all 3 ball trough switches closed AND seen by the Driver Board / MPU. Very confusing when troubleshooting the game, but that’s how the code was written. I would also suspect your switch matrix if you confirm the physical switches are closed with a working board set.

Also check that the ball return switch isn’t stuck closed and that the diode on that switch and the switches that are chained together have good diodes. In my experience, sometimes swapping the switch matrix PIA will fix weird problems like you have. Also check pinwiki - I wrote much of the system 6/7 content years ago. For diagrams of all the boards, circuit diagrams check: www.firepowerpinball.com

No probs. I do some tech support & drew many of the circuit diagrams for the firepowerpinball site.
some other board repair info at www.firepower.2ya.com - if you can’t repair your original boards, give me a shout and I can sort it out for you. If you have sockets labelled SCANBE- they must be replaced. Usually they’re ROM sockets on the CPU board. PIAs on the Driver board were soldered in place from factory on all original boards I’ve seen.

So- I’m assuming now it’s not the boards. I’m still thinking you have a short in your switch matrix.

The strange thing is the diagnostic switches (on the coin door) are *not* part of the switch matrix. The coin door switches wire directly to the CPU at connector 1J4. They are very simple and don’t use diodes. They ground pin inputs and talk directly to the MPU. Check the wires there for continuity and that the coin door switches will work through to the 1J4 connecter with 1J4 unplugged using an ohm meter. Check also where the coin door switch wires can be crimped and shorting on the coin door hinge. To see how the coin door (diag) switches are wired up, see: http://www.firepowerpinball.com/downloads/CabinetWiring.pdf
I would start there.

The switch matrix is separate, the switches ‘daisy-chain’ in rows and cols with diodes on each switch. They talk through the switch matrix PIA which is scanned by the MPU. That is the next step after you have the coin door (diag) switches working.

If you can get into the switch matrix test, only three switches 51,58,57 (L,C,R of trough) are closed with 3 balls seen in the trough. No other switches should be indicated as closed unless you active them, such as by pressing a target or rollover. Manually removing the 3 balls, no switches should be shown on the display (as closed). If you can’t get that to work, you won’t get a game start. Start checking the switch matrix rows/cols. Chasing the color coded wires between switches and testing diodes is.a.pain.in.the...

The diagram http://www.firepowerpinball.com/downloads/SwitchWiring.pdf should help if it's the switch matrix, as will the Instruction Booklet.

Let me clarify a statement I made which was a simplification. Two modes will let firepower start a game:
1. Credits are available AND 3 balls are seen in the through.
2. It’s set to ‘freeplay’ and AND 3 balls are seen in the through (51,58,57 closed)
or two in trough and one in the shooter lane (51,58,46 closed).

To set freeplay, you set function 18 (Max credits) to 0 and save. But you have to get the coin door switches to work.

Hope that helps. Apologies in advance if this is information you already know. -Richard

Good progress. Just check that the diag button Advance up/down button or switch will have continuity to gnd (cabinet braid wire will do) in one position, and open in the other. The momentary (usually red) right diag button should only have continuity to gnd while being pressed. That’s it for 1J4. Note you check them at 1J4 first and if that fails, check directly on the switch with 1J4 unplugged to show that the switch itself is working. Do any continuity measurements and diode checks with the game switched OFF.

The start button *is* part of the switch matrix, and is shown as ‘credit button” at col1 row3. That may be messing up the game (switch matrix, confusing the PiA) if it was wired incorrectly. You need the band on the diode pointing towards the col wire. Row wire (white/orange) —>| col wire (green brown). I’m not sure why you say green/red- maybe that’s the green brown. There *may* be multiple wires on the switches, which need to be there as that’s how they are ‘daisy-chained’ to the next switch. But the wire traces on the *same* col side of the switches would be the same color code. You would need to trace that wire to see if it goes to another switch in col1. If it’s the last switch, it has 1 wire only. I would check all 8 red/brown are connected together as shown in the Cabinet Wiring Diagram (col1). You can do this quickly with a continuity checker moving between switches in that Column. An finally from one of the switches to the correct pin on the MPU or driver board. Same for the Rows too, really. But each game’s harness is different. I can’t give exact routing. The logical order in the circuit diagrams and the physical harness order on the playfield and cabinet aren’t always the same due to game layout- if that makes sense. WMS would save wire by using shortest paths, usually... but not always.

Also HS reset is at col1 row8 (and confusingly) the left diag button on the coin door. Check that none of the other switches in col1 are stuck closed. Slam tilt, ball roll tilt and especially the coin-drop leaf switches short out on diode legs or get stuck closed in some other way, jammed on the white plastic wheels that the wireform moves when the coin passes by...

You save settings by pressing credit (start button) to change the stored value up/down and then use advance with the toggle set to UP TO advance all the way through the other settings past the last one. On most games it will go to ‘attract mode’ after it wraps around past the final setting. If it goes back to setting 01 (the audits I believe) then you can turn it off. Wait a couple of seconds, switch it back on and check that the setting is retained. If the game goes into setup mode 04 again when switched on, then its probably CMOS Ram on the MPU (IC15 I believe from memory haha) or batteries which is a whole other issue. Sometimes switching off/on quickly with firepower will get it into ‘attract mode’ and you can credit up with the coin-drop switches (if needed) and start a game.

Sorry for the long post, I didn’t start out intending to write a novel.

Best of luck. Firepower is a really fun game once everything is working. Steve Ritchie rules!

-Richard

OK so the start button is good.

Check the ball trough switches are closing when the balls are over them. You can use the switch matrix diag mode now and the closed switches will flash on the display with a beep for each switch closed. You need to figure out how to move between the display test/switch test/coil test etc.

As I said previously 51,58,57 (L,C,R) should be the only switches closed which is what the MPU should see in order to be able to game start. If the wiring is correct... and the switches are working, and no other switches in the cols 7 & 8 are stuck closed or wired up wrong. Diodes need to be in correct orientation and good. A complete PITA.

Sometimes the leaf switch needs adjusting very slightly - so it’s closed with ball there and open otherwise. You may need to prop up the playfield slightly on a wood block or some other non-metal support to achieve this.

Finally clean the switch contacts with a business card or folded paper... By placing it between the switch contacts, pressing the switch closed and pulling the card out. Crud on the paper shows you are cleaning the contacts. Never file switch contacts or use sandpaper, as that ruins the leaf switch for good.

If you set the game to zero credits for free play, you cannot coin it up.

If you happen to have credits on the game when you set 18 to 0, the credits will stay at whatever is there - no increase, no decrease.

Have you tried putting the game in switch test and activating the problem switch by hand? It's possible the switch is sightly out of adjustment, and the ball isn't pushing it far enough down to activate it.

Meaning they all indicate *individually* during the switch test? Except 57? Test them one a a time. That would rule out the Driver/MPU as the source of the fault. Then you have only the wiring to the PF. And diodes. That’s it as far as I can see.

Try this; Close the PF, Put one ball in the trough. Go to switch test, you should see only sw51 (Left) then without changing anything, flick another ball into the trough from the outlane. You should see 51 & 58.

If you don’t, check (and I would just replace) the diode for 57 (Right Trough switch). I know it sounds counter-intuitive, but if you look at the switch matrix, that is a ‘steering diode” and switch 57 is seen first, so would probably work to PIA anyway. They are the only 2 switches on col 8. One is on row1 other is row2. So you don’t have too many to go through.

Next logical switch diode to change is actually on *switch 50* -as that is just before the faulty one (58) on row 2. Its on the left side of the PF to the right and below the left ball lock. That’s just the way it works.

There is also a strange triangulation switch effect to the matrix (I dimly remember) which I would have to look up to know what to try next. But that has to do with multiple switches closed on different row/cols. And I don’t think that’s the prob here.

BTW- this is a decent explanation of how the switch matrix works:
https://www.flippers.be/basics/101_switch_matrix.html
This is good switch matrix info from pinwiki.com:
https://www.pinwiki.com/wiki/index.php?title=General#The_Switch_Matrix

This is a good video about the switch matrix, and explaining the ‘switch ghosting’ problem. Which I referred to as ‘switch triangulation’. This shouldn’t be your problem... it’s more often seen during gameplay where multiple switches are being closed all at the same time. Example: 3 are closed and a 4th ‘ghost switch’ also is seen as closed from a shorted diode. The faulty diode is on a diagonal in a rectangle from the ghost switch and the diode is usually shorted. See video.

Hopeful that you get there and firepower springs to life.

Try this: raise the playfield slightly pull it towards you and rest it on a wood block (or something plastic) so it is fairly level, but you can still get to the ball trough switches. Power on the game, with all 3 balls in the trough. Press the centre switch closed and press start. If the game starts, then the ball isn’t closing the center switch. You would need to bend the wire slightly up so the ball completely closes the switch, but it is open with no ball installed. Switch test will also tell you this- which is another way to tell. The switch matrix is very low voltage, but don’t touch anything metal or powered in the game when closing a switch. A plastic start button is ok.

But yes, check diodes on switch 57 and then 50. Remember to test the diode in both directions by reversing the test leads. It should conduct in one direction only, and be ‘open’ with the test leads the opposite way around. Apologies if you understood this already, i’m adding it for completeness. Personally I would replace 57 and then 50 in that order and test each time for game start and diag switch test for further clues.

I edited this post so you may want to read it again.

Are your switches the ones where they were put together 'backwards' by the factory? (Flat faces both facing the same way instead of facing each other) If so, just replace the blades as likely the plating is gone and won't be reliable. I buy switch contacts and peen them into blades myself but you can also just get switches already made up from Marcospec or various other places.

The 2 on the plate look ok the one to the right is reversed, but that one works.

Test all the other switches in the row and columns one at a time and make sure they all work. Look at the ball roll tilt on the left specifically as well. There's got to be a bum switch somewhere else that's causing this to not read. Make sure each switch activates one and only one switch in test.

Sounds like you may be reading resistance through the switch / diode with it open. Put a thin card between the switch blades and test again, just to take that out of the equation.

Are you sure switch 58 in row 2 isn’t shorting to the diode somehow? check the ends sicking out and that the sandwich insulation looks good and it’s not grounding to the trough plate. check the wiring to the switch is as the other trough switches. Leads from the diode can not cross, or even touch slightly. Band on the diode points AWAY from the white wire.

Yes, I would expect it to conduct 0.5-0.7 in one direction and be open the other way. Make sure you are on a diode setting on the meter looks like ->|. Doing it on ohms or a continuity setting may not properly check the blocking property, as it won’t bias the diode with enough voltage.

Did you do the same check on switch 50? Do you get the same reading there? What about others on that row: sw42, sw34... etc.

Then test diodes with the harness unplugged from header 2J2 & 2J3 on the Driver board. Stick your meter lead in the header for col 8 (green/gray) and the other lead into row 1 (white brown). To avoid harming the connector, I stick in paper clips and wrap them around the meter leads. Even easier to do if you have alligator clips. Press each switch in the row, moving the column lead back 1 position in the connector and pressing the appropriate switch.
So col8/row1 press sw57. col7/row1 press sw49.

I’m hoping you understand what I mean. You’re checking the diode all the way through the harness and switch. You will likely need help finding and pressing switches. It’s harder on your own for sure. Sorry this sucks, but it’s the only way I’m sure will isolate the problem. Look for differences in readings.

In one orientation of the leads, they all read 0.5-.07v approx. The other way around they should all be the same - open or no reading. I’ll leave it to you if you want to swap leads for each switch, or do them all and then swap leads and do them all in order again. I prefer the former.

Afterwards check each switch you got. funny reading on and the soldering and for stray wires for each lead. I just replace any diode I think may be bad, and move on. They cost pennies.

Sure, or put a paper card between the switch blades. Good catch.
I’m pretty sure that with coils, you have to unsolder one leg of the diode before testing. That’s what I do.

It’s going to be a faulty switch or diode somewhere.
You can try sw50.
Also go back to check sw01 to sw09 shown here on pg10 of this excelllent booklet:
http://www.firepowerpinball.com/2ya/downloads/InstructionBooklet.pdf

Use the diag switch test for each of these, make sure only sw1,2,3,.. is shown on the display as 01, -2, etc and *no other* switches show closed when you make those switches. Check wiring & diodes on any that close 2 switches. And around any ghost switch that closes with it.

Check diodes and wiring on the plumb bob tilt (shown as 7D1 on Cabinet Wiring diagram) which is on col1/row1. Take the plumb bob off, so we know it isn’t stuck closed. You can set if back up once the game is working.
Same for the ball roll tilt (shown as 7D2 on Cabinet Wiring diagram) which looks like a metal angle bracket with a slot it, near the plumb bob tilt. The little ball that rolled down to the switch if the front of the cab was lifted & dropped is usually missing. Make sure the metal switch at the end isn’t grounded out, and that the diode is good. It’s on col1/row2. Row2 is the row with the faulty switch (58). I don't want to ignore those just because they aren't on the playfield.

Also check the ‘slam tilt’ which is on the underside of the playfield and has a weighted switch the vibrates and closes if the game is slammed around, it should be marked ‘slam tilt’ and the same rules apply: not stuck closed - check for diode good & operation in switch test. It should only close 1 switch sw47 when tested.

Then I’d work my way up row 2, from ball roll tilt (sw47) to sw10, sw18, sw26, sw34, sw42, sw50...
Using the operation for diag switch test. Only one switch should be shown at a time as they are closed.
Then use the procedure above of checking the diodes and switches with the game off from the disconnected row/col headers all the way through the wires to the switch-diode you want to test. Connection on row 2 should be open, and then show one diode in one direction for each column and switch closed. They should show no reading with the test leads reversed.

I’m out of ideas.

Best Wishes.
-Richard