I picked up a project Black Hole, and plan to use this place to (hopefully) bring it back to life so that it can be enjoyed as one of the most unique and fun games around.

1.) Upon hooking up all the backbox connectors and powering on, I had the following:
- Some GI lights in the backbox in a sequenced pattern
- The display in the bottom left corner of the playfield with a "0" in the display
- Attract mode voice.
Nothing else. No displays, playfield, lights, etc.

2.) All fuses checked, and one blown for a lower playfield pop-bumper.

3.) Found 3 connectors unplugged in the lower cabinet. A12-7, A12-8, A15-1.
Upon powering up the game (quickly), I have a slew of solenoids locked on. I may have missed some, but there are at least 10 of them. The only playfield lamp that lights is the Shoot Again "When Lit" lamp. The only backbox lamp that lights is the "Tilt" lamp. Only display is still the "0" in the lower left corner of the PF.

Any help along the way would be greatly appreciated.

The coils lock on. I don't see any commonality at first glance, but I'm betting that's why the A12-8 connector (not sure about the other 2 in the cabinet) were unnecessarily unplugged. Oddly, I would have expected a myriad of blown fuses, so either the lock on current draw is slow, or the problem was noticed right away.

I'm just laying this thread out there as a brain to paper process so others can maybe glean something useful as I go through. As a primarily Bally/Williams/Stern guy, I'm already noticing quitea few head scratchers in the "WTF were the engineers thinking?" department.

Next step will be verifying PS voltages and checking for battery corrosion.

Guys, I'm sorry... had two back to back business trips and the hurricane to deal with (we have property in Cape Coral, FL sigh).

So here's where I'm at.
Voltage test on the PSU...
60VAC: 63VAC
5V: 5.03V
8V: 8.1V
42V: ~49V
60V: ~63V

Everything looks really solid there.

The boards all look clean, and the CPU board was updated (will check the revision on there and post a picture or two later). There is NO battery, which makes no sense to me. I don't see NVRAM present, but that would be more of an annoyance rather than the game not booting.

If I disconnect the CPU-Driverboard edge connectors, I get playfield GI. If I reconnect that edge connector, I get no GI and a large number of solenoids lock on.

OK, now that my Black Pyramid is fully repaired, shopped and functional, I decided to come back to this.

I noticed that some prior work had been done to the power supply board. In verifying all of the components, I noticed someone had replaced CR7, but had replaced R10 with a 680K ohm resistor instead of 680 ohm. So I corrected that and did the LED mods for 60V to that board, and added a 5V LED to my CPU, which is a modded 1st gen to 2nd gen (D107) with the single 2716 EPROM. I also replaced the old orange filter cap in the bottom of the cabinet.

So here's where I'm at, if I turn on the game with the CPU <--> Driver interconnect unplugged, I get all of the upper playfield and backbox GI (nothing in the lower PF, which is correct?), no displays, and I DO get the repeated attract mode voice. Power supply voltages all look spot on.

If I connect the CPU <---> Driver board interconnect, I get NO GI, and a whole bunch of switched lamps and solenoids lock on.

I undid the connector, turned the game on, and noticed that at the interconnect, the right-most pin (presumably ground), has continuity to all of the other pins. So I suspect I have a CPU problem? I assume that even without this interconnect, the CPU should boot and do something, no?

Any way to bench test, work, verify the CPU to resolve this issue?

Update, 6502 chip... RESET line is good (starts low for a split second and then goes hi). IRQ line however is stuck high.
Also, the bench supply is 5.05V, but when hooked up to the CPU board, the voltage across my J1 alligator clips drops to 4.6V.

Any ideas on where to start?

I appreciate that. In 20 years I have yet to put a repro board of any kind in any of my games. I actually enjoy the learning and challenge of the repair process. Sometimes they're easy, sometimes they aren't. Unfortunately, my Gottlieb experience is very limited and the online resources are thorough, but not so much in MPU boot issues/repair procedures. Hopefully one of the many greats (Chris, Ed, Andy, Jerry, Ken, etc.) can lend a hand.

Correct, yes I verified that everything is "shorted" to ground. Or something is pulling everything down. The CPU is definitely not booting correctly. I've got good reset, lines 37/39 are pulsing nicely, but otherwise, signals are floating or incorrect. There's gotta be a smoking gun here. The previous owner said it was working.

No. I was going to go through the chips painstakingly w/o power to see if there were any overlapped signals that may have been linked with solder or something, but I'm not seeing that so far.

But I should see pulsing on the IRQ and R/W lines. I don't. They're both hi. The address/data bus lines aren't pulsing either, they're floating garbage.

The clock (U1 pin 39) is the ONLY thing with a pulsing signal on the logic probe, as well as U1 pin 37. The reset line also tests good -- starts low for a split second then goes hi.

If I connect the board with only the power supply in and only the displays connector going out, I get a "1" on the status display by the left flipper. I don't get anything anywhere else.

All my PSU board voltages are perfect (5.07V at 5V, 67V at 60, 48V at 42 and 8.4V at 8). However, if I measure the +5V at the filter cap immediately to the right of the MPU connector from the power supply, I'm getting 4.6V which is obviously bad. This is the same drop I measured with the bench supply. So something on the MPU is sucking a massive 0.5V which surely is causing a failure to boot.

Yep orange cap replaced with a 12,000 uF one, grounding mods done (although that doesn't really apply here) -- especially on the bench. We've got a massive 0.5V drop somewhere on the 5V rail for this board, which in my mind means there's a short somewhere. I don't have any obvious means to trace it down. Frustrating.

Ed,

My bench supply for board work is just a repurposed ATX power supply out of my old desktop PC. Normally I build molex connectors for Williams, Bally, etc, but in this case I just ran an alligator clip between a 5V tap and a ground tap to J1 as pictured in the Pinwiki page. I then run a basic rocker switch on the ATX between the green sense line and a ground line to allow me to turn on/off the ATX with a flick It works great.

Obviously it's not current limiting. Do I want to measure current across the alligator clips at J1 or somewhere else?

Still looking for ideas. Jerry Clause has given me some ideas on FB, but so far nothing has turned up the smoking gun.

1.) I used the diode check on all the LS chips and found a pin on Z17 and a pin on Z21 grounded. Unfortunately, these are output pins to the displays, so while those chips needed to be replaced that's not the problem. I also found one of the 1N4148 diodes to one of the dip switches was bad. Replaced but also not the main problem.

2.) Again I'm getting a large .5V drop between the power supply and the board. Testing right at J1 or across the filtering cap (replaced for good measure), I've got 4.6V instead of the 5.08 supplied. On the far end of the board, I'm measuring 4.55V at those chips... so the drop across the board is what I'd expect (< 0.1V).

3.) With a lead on ground and the power off, I used the schematic and tested all the chip pins for continuity to ground. I then did the same with the power off, one lead on +5V and testing the chips for +5V. Everything checked out except for Z36, pin 11, which the schematics show is an unused pin tied to ground. However, the board traces have it connected to pin 8 which is an output from pin 9 to the R/W circuitry. Not sure if this was corrected in a later revision?

4.) Here's what's odd. With the power OFF. If I put the + lead on +5V and check all the pins with the - lead, everything checks out. If I flip the leads, putting the + lead on ground and check all the pins, I get a quick "blip" on the continuity tone when I touch any chip's ground pin.
If I APPLY power to the board and perform the same test...+ lead on +5V and test the chip pins, everything is fine. If I reverse the leads and apply the + lead to ground and the - lead across all the chip pins, I've got continuity everywhere. Why would reversing the leads change anything? This behavior makes no sense to me.

So an (embarrassing) update. After removing known bad Z17 and Z21 chips, I supposed I could have placed the board back in the game, but I continued on the bench. I replaced Q1 through Q4 as those readings were questionable. After that, my voltages at across J1 actually got worse (4.4V) instead of the same or better. Normally, when using a bench supply, I'll built a molex connector to the board, but since Sys 80s use unique connectors, I figured I'd run alligator clips. I had two alligator clips running from a +5V and Gnd wire on the switching PS to two 18 gauge wires I had temporarily soldered to the +5V and Gnd edges on the MPU.

On a whim, I decided to remove the alligator clips and directly twist the wires from the PSU to my makeshift wires coming off J1. Lo and behold, 5.05V. Never in a million years. Has anyone heard of this before? A .5 to .6 drop in voltage due to a few foot 6-8" long alligator clips?

Now, I still have a lot of floating signals, but I also have some strong pulsing and solid hi/lo signals where I didn't before. I've definitely got some work ahead, and will probably post back here as I re-establish my working state, but I'm certainly in a better position having removed Z17/Z21. Will replace the crystal just due to its proximity to the old battery, although I don't see obvious signs of corrosion.

I do not have an oscilloscope. I have no way to verify whether it's good. I set my DMM to frequency, but I'm not getting useful readings across the legs.

Alright, I finally resurrected this beast. Purchased an FR300 and am regretting not getting one 10 years ago. Literally knocks the time to remove chips by 90%!

So here's what I did.... Z17, Z21 and Z36 each had a bad or dead pin despite proper continuity. Removed chip, socketed and replaced. All 3 chips now test correctly. Replaced and socketed the CPU and well as each of the 3 RIOT chips. I don't feel the originals were bad, but since I had sockets, a new desoldering iron and new chips available, I felt motivated. Replaced the crystal as well.

I've got a game with a solid 5V across the rail, and the reset circuit is good (starts low, goes hi after a half second). R/W is pulsing and some of the address lines are pulsing. However, most of the other lines are floating. My IRQ line, which is the next step down the flow chart is stuck hi. Continuity wise, it traces out correctly. On the far left end, the 3K ohm resistor tying it to 5V tests good.

G-P-E (Ed), Ken, Chris and any other Gottlieb Sys80 experts....what could hold the IRQ line high? I feel like there's some stupid thing causing this not to boot correctly.

OK, spent some time on this this evening. There's a LOT more activity than I thought, but with odd behavior.

I'm not seeing any continuity, grounding or short issues so far...but I observe the following.

On U2/U3, all readings appear to be normal with pulsing on all address/data lines except A0, which appears* floating. On both A0, if I have the logic probe on the line when I power the board on, I get a pulsing signal, but as soon as I remove the logic probe and re-apply it, I get a floating signal. I'm wondering if the initial "pulsing" is erratic enough that the logic probe can't pick it back up again? I've never ever seen this behavior before.

Oddity #2, U1 19 is a really slow pulse (long low then a quick blip of hi) -- designated AB10. U2/U3 pin 19 are designated as BAB10, and also have the same very slow pulse. What's odd is that according to the schematics, BAB10 and NOT BAB10 are created by running AB10 through the 7404 hex inverter at Z12 using pins 8 through 11. However, pins 8 through 11 aren't even connected to the circuitry! There are no traces running to any of these 4 pins top or bottom side. Z12 pin 9 and 11 are dead inputs. So now I'm baffled.

Oddity #3, U1 pin 20 is stuck low.

IRQ line remains stuck hi.

I have a single 2716 EPROM (verified good). It has good signals coming out of it.

I'm stumped. Does A0 connect to anything else besides U1-U6 and Z5?? I don't understand why this signal has this weird behavior when I have no other issues on A1-A7 nor D0-D7.

The only other thing I noticed is that in the delay circuit, The emitter and collector of Q2 are dead along with their adjacent legs of R44/45/46. Everything tests good individually and with continuity. However, this may be perfectly normal that after the board is powered, current simply doesn't flow through this circuit due to the other resistors/transistors in use? Since the reset line behaves correctly, I'm guessing this is all fine.

Grabbing at straws now.

To followup, board is repaired and working!

After replacing the CPU and 3 RIOT chips per above (along with a few output LS74xx that had a couple dead pins), I still had a stuck high IRQ and some weird addressing signals. I went ahead and bought the Pinitech Gottlieb System 80 tester. So today, after removing U3 and the game ROM in order to use the tester, I fired it up and the diagnostic LEDs passed with flying colors. I bought the extended TEST ROM as well and those also passed! Odd I thought.

That meant I either had a bad masked ROM at U3 or a bad EPROM. I figured the former since I had tested that EPROM wayyyyyy back when I got the game and it wouldn't boot. However, since I had no way to test U3, I through the EPROM in my G4-QX reader and it came up blank!!! WTF. I attempted to write the game ROM back to it, and it failed. Grabbed a spare 2716 I had, erased it, successfully burned the code, through it back in the board with U3 and HOLY SH-T I have perfect signals on every line!!!! Put it in the game, prayed, turned it on and it boots and mostly plays!!

I've got a couple bad displays and some quirky switch behavior, but solenoids, lights, etc mostly work. Upper 4 flipper works. Sound/music work. So we're well on our way now!

Now that I have a mostly working (at least booting) game, I can begin to troubleshoot the (hopefully) other minor issues with the game.

Where I'm stuck now is with a display segment issue in the lower 2 displays. Displays all tested good via swap into the upper 2 display connectors.

During the display test (19), All segments light up on the top 2 displays and the 2 playfield displays. On the lower two "B" displays, only the 'h' segment lights.

Looking at the schematics the B display a thru g segments are controlled by Z21. Sure enough, all the outputs on Z21 are stuck low, as compared to the correct pulsing signals I hear on the A display line at Z19. I've replaced Z21 with a 74LS48 (actually tried two new ones) to no avail. I then even replaced the upstream Z20 74LS175 to no avail.

The only thing that is unique on Z20 as compared to Z18 is the CK signal on pin 9, which is PA5 originating from U5. Indeed the CK signal, while pulsing, sounds "different" on the logic probe as compared to the clock signal on Z20.

I'm not sure where to go from here. My Pinitech Gottlieb system 80 test chip as well as the Marco extended test chip passed all the RIOTs with flying colors.

Help!

I ended up building a test rig with an Arduino and a breadboard and wrote a simple computer program to test the 74LS48 chips I bought new from Marco. Sure enough, both tested bad. Steve @ Marco was a rockstar and immediately overnighted me 2 new chips and verified he didn't have any more from the junk lot I send him a picture of. New ones arrived this afternoon. Both tested GOOD in my test rig. Placed one in my Sys80 board and I have working bottom displays!!

Now onto the rest of the game.

I swear this Black Hole is going to be the death of me. Now that I have (hopefully?) resolved the display issue, I replaced some bad lamps (actually LED'd all of the inserts) and fired up a few games.

Immediately I'm noticed the following behavior as soon as a ball hits the shooter lane:
1.) I'm getting a ton of 10 point registers on the LOWER playfield display anytime a coil fires (flippers, ball into the shooter lane, etc.). It seemed that when I lifted the upper playfield into the vertical position that this stopped (need to do more testing). I looked at all of the switches on the lower PF and none of them appear closed or within vibration distance of closed.
2.) The tilt tilt tilt tilt tilt... sound track plays repeatedly when the points are registering, along with other audio. However the game doesn't actually tilt? (flippers flip, points registered, etc.). This is by far the oddest behavior!
3.) F22 fuse blows on the center top pop-bumper on the lower playfield.

OK down to the final last issue with this beast after taking a break. Finished up all of the ground mods, but no dice. (The pop-bumper issue above was a board and has been resolved).

The remaining odd behavior is an audio one.

Usually, if I boot the game cold and play a couple balls, it's fine. After that I see the following behavior...(see video below).

When the ball goes from the trough into the shooter lane, instead of a rather cool sound effect, it's replaced by the "Tilt...tilt...tilt...tilt...tilt...tillllllllt sound effect" (the game is not in tilt). You can proceed to play the ball normally, but there is no background music.

I'm not understanding what is causing the wrong audio to play here (and the background music drop out), as it does typically start up and play fine initially.

How can I resolve this?

After feeling good about other repairs, I decided to come back to this today. I figured it was an audio address line issue, as ROMs should either work or not work. I went to take the connector off the board to remove it for ROM checking and I see a wire just dangling there. WTF. It looks like someone spliced it back with no solder, tape, etc. Sure enough I twisted them back together just to test and bam... perfect audio. Sigh.

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