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(Topic ID: 146833)

Bally Special Force (6803, 1986): switch woes.


By anthony691

4 years ago



Topic Stats

  • 27 posts
  • 10 Pinsiders participating
  • Latest reply 4 years ago by mtgedney
  • Topic is favorited by 3 Pinsiders

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bally6803_keypad.jpg

#1 4 years ago

I bought a Special Force last weekend and I'm trying to work out a few switch issues. I've got an entire row of switches out (chopper bottom, middle pop, C, M, bonus X row).

No stuck switches. Nothing in this row registers at all. Everything else in the game works great.

All these switches look good visually and continuity to MPU measures good. The MPU has two mismatched PIAs (which makes me think the previous owner swapped at least one).

What steps should I take toward resolving this? I'm leaning toward suspecting board trouble, which is drag. I'm hoping the pinside community can point me in the right direction and make it a bit less painful.

#2 4 years ago

I guess I will add the game has another issue that probably points toward the board:

The audit menu behaves bizarrely.

When the self test button on the coin door is hit, the machine enters audit mode. A and B cycle functions appropriately. "Enter" works to enter into self test submenu, but will not work to enter an individual test, which cannot be started. Most numeric buttons on the keypad cause the machine to put out a bomb sound in any part of the audit menu, and the audit menu is reinitialized (!). When cycling through the self test submenu, a numeric key, when hit, appears on the display. A second numeric press will cause the bomb sound and restart the audit menu (inputting the values for the tests did not work).

The clear button works as expected, the "game" button does not.

The board still has its original battery, which hasn't leaked but could be causing memory problems. I'll be replacing it shortly (likely this weekend).

I tried disconnecting the audit remote, but it has no effect on the switch matrix issue.

Edit:
Went ahead and swapped out old battery for a battery pack with a blocking diode and reseated each PIA and swapped their positions.

Still boots, but it lost its free play setting, the audit menu is still screwed up, and I discovered the coin door is isn't working. High score initials (only) are junk characters now. Needs reset from audit menu, which isn't working.

Keypad is wrapped in tape. I'll have to dismantle it and see whether there is a problem there, but now I can't even test the dead switch row.

Will look to the coin door for issues.

#3 4 years ago

Additional question:

What on earth does "middle coin" refer to? All of the games I have seen, like mine, have only two coin slots.

#4 4 years ago

Was this the one on MKE clist for $700?

If so, NICE score!

#5 4 years ago

Middle coin might not be installed in your game. It would be a coin door with 3 coin slots. Most only have 2 coin slots.

The keypad shares switches with the PF. If you have non working switches on the PF. You will probably have non working buttons on the keypad.

If your switches are not working right, check the switch plugs on the MPU board. Check the female plug for wires fallen out of the IDC connector. On the male pins, check for cracked solder joints.

You can check continuity from the PF to the MPU board past the connector.

I would say most likely have connector issue.

#6 4 years ago
Quoted from Whysnow:

Was this the one on MKE clist for $700?
If so, NICE score!

Yep, that's the one.

It'll be a cool game once I get the switch problems sorted out.

#7 4 years ago
Quoted from barakandl:

Middle coin might not be installed in your game. It would be a coin door with 3 coin slots. Most only have 2 coin slots.
The keypad shares switches with the PF. If you have non working switches on the PF. You will probably have non working buttons on the keypad.
If your switches are not working right, check the switch plugs on the MPU board. Check the female plug for wires fallen out of the IDC connector. On the male pins, check for cracked solder joints.
You can check continuity from the PF to the MPU board past the connector.
I would say most likely have connector issue.

Thanks for the guidance. For whatever reason, the connectors mostly escaped my scrutiny (they look pretty good). I'll try thoroughly metering for continuity. Might just go ahead and replace them.

I'm also going to try manually shorting out the keypad pins for "Enter" to see what, if anything, that does.

#8 4 years ago

Come on man!! Bally testing is as easy as A B C! hahaha just kidding, what a pain that dumb keypad is.

I believe you want to be pushing the advance to begin tests, not enter. Enter is used when saving an audit value.

Here is a tip... do a factory reset. I have noticed testing NVRAMs, scrambled RAM data, or RAM from a different system can cause issues. Audits will have erroneous out of range values stored in them giving possible odd effects like not being able to start a game, not being able to add credits, and more. Go to the factory reset audit and set it for "65"(bally 6803 reset number is 65 and used in a few places). Hit enter to save the audit, back out of the menu to make sure it saved and power cycle. Next boot up will be default factory audit values.

#9 4 years ago
Quoted from barakandl:

Come on man!! Bally testing is as easy as A B C! hahaha just kidding, what a pain that dumb keypad is.
I believe you want to be pushing the advance to begin tests, not enter. Enter is used when saving an audit value.

I couldn't really find very clear guidance for how to work the the ridiculous audits.

By "advance" do you mean the A button?

#10 4 years ago

By chance I watched a TNT amusements about this machine the other day

(watch around 5:20)

Todd mentions you have to make sure the capacitors across the switches are okay, or you will have problems with the switches. Not sure if its related to your switch problem, but might be worth checking

#11 4 years ago

Glad people are fixing these games up. I really enjoy my special force Just picked up a second nicer one lol. Now i have one with regular backglass and one with the german girls glass.
Cant help you with your switch issues but never hurts to bump the thread.

#12 4 years ago

Had a similar issue and discovered a bad voltage read on the respective header pin relating to the column that was down. This info quickly isolated the issue to a board related fault for me.

#13 4 years ago
Quoted from Jimmylad:

Had a similar issue and discovered a bad voltage read on the respective header pin relating to the column that was down. This info quickly isolated the issue to a board related fault for me.

Were you able to work out what the board related fault was?

#14 4 years ago

I need to do a cheat sheet / chart for these 6803 keypads for the 64 Switch Matrix Tester (diagnostic tool) I sell for testing switch issues. It's been on the agenda.. and in situations like this it'd get the ridiculously horrible Bally 6803 keypad out of the equation. I've had just a few Bally 6803 games and there's usually been a few keys that don't work.. unless you press them with ungodly force. Maybe I'll knock that out quick this morning.

And yeah, the keypad is a bad design as everyone knows.. I guess I get why they thought entering numbers and going direct to an adjustment made sense.. programmer/engineer thinking that makes sense that doesn't make sense to anyone else. Regardless, having this extra keypad in the game is kind of lame..especially when it malfunctions, goes missing or is just loose inside there getting knocked around as the game is moved.

Anyway, sounds like you checked continuity from the switches to the MPU. Looks like your switch issues are on I2 (return2), so header J4-8 on the MPU. They're showing I2 (return2) going to PB02 (U8 6821 PIA). There's a 1.2k resistor in-line and also a 390pf capacitor to ground on the switches. With the game off.. and J4 connector (playfield switch returns) connected, have you measured continuity from the switch to R107 (that's the 1.2k resistor for the I2 return)? You'll have to figure out which side to of the resistor to measure at. If continuity measures fine there.. then also check that the resistor measures out correctly as 1.2k. Other than that, it's looking like the 6821 is next in-line as far as circuitry goes.

To verify the switches, you should be able to use a diode and two alligator clips to connect a strobe and return line while in a game. Disconnect the J4 connector on the MPU and try faking a switch closure on one of the non-working switches. The banded side of the diode would go to the strobe... non-banded side would go to the return. So get a 1n4148 or 1n4001/1n4004, etc diode and connect an alligator clip to the banded side.. then the other end to J4-15 (strobe0, pin 15 of J4). Then connect another alligator clip to the non-banded side of the diode and touch the other end to J4-8 (return2, pin 8 of J4).

Look at the Strange Science Operator's Manual page 54 for a switch chart -- the switch names won't be right but the strobe/return lines are clearly labeled there versus the Special Force manual. http://mirror2.ipdb.org/files/2396/Bally_1986_Strange_Science_English_Operating_Manual.pdf

---
http://www.pinitech.com - "Pinball Inspired Technology"
Kits, upgrades and test equipment for pinball machines

#15 4 years ago

Thanks for all the help!

Certainly enough guidance here to get me started in the right direction.

#16 4 years ago

Ok.. haven't verified this [yet] but this would be how the keypad maps out to the 64 Switch Matrix Tester. Not that this helps the OP out, but the diode test I described above should be the simple / cheap way of doing it. The same wire harness used for testing playfield switches with the 64 Switch Matrix Tester should get you simulating the keypad when in test mode.. from the looks of it the J3 (cabinet switches) and J4 (playfield switches) go to the same 6821 lines, so no need to create an additional wire harness.

bally6803_keypad.jpg

OP - diode test described above should work just fine. Might want to consider a switch tester sometime in the future if you get tired of testing with alligator clips/diodes and can justify the expense, but either way will help you narrow down these kind of issues to just the board.. or something between the board and the switch/keypad (ie. connector, wiring, switch itself, or cruddy Bally 6803 keypad hehe).

---
http://www.pinitech.com - "Pinball Inspired Technology"
Kits, upgrades and test equipment for pinball machines

#17 4 years ago

My to do list looks something like:
1) Try faking keypad input. Do factory reset if successful.
2) Try faking switch closures for the dead PF switch row (even if I can't get a game started or make audits work, I can test this because the game features a power on switch test).
3) If either or both tests fail, replace both 6821 PIAs. Failing that, replace sockets.
4) If both tests are successful, replace connectors (already in the mail), inspect wiring closely, start replacing switch diodes and caps, etc.

Would 100 volt 0.15a be an appropriate value diode to use for faking switch inputs (w/ band facing strobe)?

#18 4 years ago
Quoted from anthony691:

Would 100 volt 0.15a be an appropriate value diode to use for faking switch inputs (w/ band facing strobe)?

What's the part number of the diode? You'll need a general purpose silicon diode.. 1n400x or 1n4148, 1n914 should work. The 1n4148 is 100v 0.3A forward current. Your .15a one should be okay.. not like there's any significant amperage going through switches.

Your to-do list looks solid

#19 4 years ago

Successfully troubleshot. Bad IDC connectors on J3 and J4. Replacements (molex type) are in the mail.

Thanks again for all the help!

In addition to fixing the connectors, I'll be doing a complete PF teardown, replacing the sound board trim pot, replacing a pop bumper body with cracked clips, replacing rusty levelers, replacing flipper bats, and rebuilding both flippers (reversing left/right to get around some stripped out holes). Later on I'll probably replace all the drop targets.

Wasn't anticipating such an involved project, but I'm pleased with the results so far. This game really seems like it sat for the better part of twenty years.

#20 4 years ago
Quoted from anthony691:

Successfully troubleshot. Bad IDC connectors on J3 and J4. Replacements (molex type) are in the mail.
Thanks again for all the help!

Awesome! Often something easy like that Glad you found the problem!

#21 4 years ago
Quoted from anthony691:

Were you able to work out what the board related fault was?

Yeah it was a chip/ic type 7406 that I was able to easily verify by swapping a good chip off the board for a quick determination. This was for a Williams fire power using kohout board with pull out type ic s.

1 week later
#22 4 years ago

All the switch issues are worked out (connectors indeed)

Only remaining problems are that some of the DTs don't consistently catch (the weapon DT is a generic replacement) and my flipper rebuild went badly.

I wired one of the flippers incorrectly (the wire colors for ground and coil voltage were super similar). It blew the line fuse and flipper fuse.

I was surprised to find after fixing the wiring and replacing the fuses that the coil primary winding actually failed. Now I've got to wait for a replacement flipper coil...

#23 4 years ago

Many of the problems I have seen on the 6803 system over the years have been mostly those silly IDC connectors, especially for the switch matrix.

2 months later
#24 4 years ago

I too picked up a Special Force machine about 1 month ago. Hoping someone could help. Sporadically, the machine will award rockets in sequence without hitting the targets. Often it will reward a letter each time the right flipper is engaged. I checked under the playfield and O switch was missing a capacitor and C switch had a broken one. Put new ones on but didn't help. Would I be wrong next to look at the diodes on each letter? The really perplexing issue is why would all six be faulty? Not sure how switch matrix is setup on this machine?

#25 4 years ago

remember to check the inlane switch gaps, each pass over the inlane gives a letter towards rocket

#26 4 years ago

Awesome suggestion. I will check that.

#27 4 years ago

That was it. Thx.

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