From 3 into 1 game. One game was destroyed to get it to fit in a dumpster, only the back box and playfield survived by someone stepping in. One was complete but had been very wet at some time, and some spare parts from a third were needed. All of this was brought together in an attempt to bring one complete machine back to life with plenty of spares. Two issues remain that I know of. (Using an Elenco Logic Probe LP-560)

#1 Both of the lower playfield Drop Targets are not resetting. For a while the Three Pos. Bank Targets worked but now has also failed. - The pair of transistors for both of these solenoids located on the A3 Driver Board tests good. Wiring tested good between Driver Board and solenoids. I have 24VDC power at wire 488, F18 and 377, F20. I will need to double check the A3J1/A1J4 jumper for a good connection before the moving on to the 7416 chip.

Here is my question. If all the targets are dropped, what should I see on the 7416 chip found in position Z30, legs 2&4, & 1&3? I might also need to know what I should find on the 74LS139 in position Z28, legs 12 & 11?

#2 Lower playfield Bonus Score Display (5A4-J1) and Game Indicator (1A5-J1) are missing segment C used in numbers 3 and 7 in all positions. Wiring tested good between Control Board and displays. Both the Bonus Display and Game Indicator Displays segment C's are carried on the same wire 884 (Red, Red, Slate) in wire bundle C and travel to plug coupling plugs A10J5 \ A10P5 and onto the A1 Control Board via A1-J2 wire Plug Connector 19 on wire 884. The conductor tests good. To me this indicates a failure on A1 Control Board.

Here is my question. If I have the number seven or three indicated on the Bonus Score Display or Game Status Indicator, what should I see on the 7448 chip found in position Z23, leg 11? I'm guessing high would be indicated. If I don't get high, is it likely the 7448(Z23) because I am only missing one segment?

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Update on #1 Resolved!

"#1 Both of the lower playfield Drop Targets are not resetting."

I was really surprised to read an article about the side rail contacts on system 80 boards that explained that if a contact pad isn't gleaming like high polished silver and more like a dull Nickle color this could prevent signals from being transmitted due to this tarnish. Even using a pink erasure didn't seem to accomplish this or any better results. I saw a jeweler on a YouTube video use a fiberglass pencil while polishing details in an ornate ring. Polishing some finite details successfully this way. So purchased a Pixiss Scratch Brush Pen Set with four different pencils, Fiberglass, Steel, Brass and Nylon. I polished all board contacts with the Fiberglass pencil and the lower playfield Drop Targets now work.

Update on #2 More questions.

"#2 Lower playfield Bonus Score Display (5A4-J1) and Game Indicator (1A5-J1) are missing segment C used in numbers 3 and 7 in all positions."

I failed to mention that segment C works when a Zero is lit so I am guessing that this is not a bad 7448 in position Z23 but maybe its the 74175 in position Z22 that possibly acts as a decoder? What do you guys think?

This is a small punch list so I am happy about that. This game has come a long way to get here. I appreciate any insight you can offer. Thank you.

Tom

Thanks for straitening me out on the 74175. I replaced the year old 7448, no change. I disconnected the 4 digit display, no change to the 6 digit display. I disconnected the 6 digit display, no change to the 4. I replaced the six digit display with a know good display and no change. The 4 Player scores displays for all 4 players work as they should. I will look for a short by examining all plugs and conductors from A1J2 - 1A5J1. I will next check for any conductivity between C and any other conductors in the bundle.

So here is what I did. I checked the 4 digit display first when it was only showing "0" credits and on Pin 4 it had a pulse. I ran it up to three credits and advanced it to ball three. This way neither digit was showing the C segment being lit. Pin 4 was a LO.

Thanks,
Tom

C segment lights on numbers 4, 5, 6 8, 9 and 0. C segment does not light for numbers 3 and 7. There are no instances when this segment lights when it shouldn't.

I checked the output of segment C on Z23, position 11. It was High (I imagined it to be pulled down Low due to a short ). I then checked side connector A1J2 Position 19 it was Low. I unplugged A10P5 and A10J5 and then checked 19 again and it was still Low and on Z23, position 11 was still High. I'm thinking there is a problem on the board. Maybe there is an open solder connection at the socket or a trace?

Tom

I just discovered I had inverted the pin configuration of Z23, I was reading pin/leg 3 not 11. I will set this up again and report the correct findings. It seems almost certain that pin 11 of Z23 and position 19 on connector A1J2 would agree (I examined side connect A1J2 and found it too be good).

I will look for a short circuit on the MPU board between Z23 pin 11 and pin 15.

UPDATED:

Same conditions as before, credit 3, ball 3. Pin 11 of Z23 is Low as well as position 19 on connector A1J2. Pin 15 of Z23 is also Low. I disconnected M/F plugs A10P5 and A10J5 and the conditions didn't change. Then I disconnected side connector A1J2 and the conditions didn't change.

Tom

Look what I found on the reverse side of the A1 CPU board at 20X power. To the left is Pin 11 of Z23. On the right is a trace that leads to Pin 15 of Z23. I took a pair of micro tweezers and flicked off the offending solder bridge that was totally undetectable to the human eye. OHMS Meter shows infinite between 11 & 15.

Thank you Quench for keeping me on the strait and narrow path to success! Appreciate you!!!

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Quench I just noticed that while in attract mode the third Zero going left to right is not lighting on Player 1, 2 and also the lower playfield bonus display. I pushed on A1J2 and A1J3, neither one moved but it resolved just the same. These are new side connector pins and I just cleaned the side connector pads with a fiberglass pencil the other day. These kind of intermittent issues are a bit unnerving when you go the extra mile to insure good connectivity. Is there something more I can do? - Tom

For the time being this has cleared up. I was able to have 12 trouble free games and then the 3 Pos. Bank failed to reset. I will get back into why Sol. 6 isn't doing its job tomorrow. Both of these issues seem to have been caused by side terminals. It really frustrating to me because I went through all the tedious time and expense to re-pin every connector and the clean all the pads with a fiberglass pencil and they still act flaky.

In this case a MPS-U45 transistor, Q63 failed (the legs of both Emitter and Base were broken). This caused the Q64, a 2N3055 to open preventing the 3 Pos. Bank from resetting. So no side terminals acting flaky this time. I am not certain why there was a failure as of yet. The MPS-U45 transistor legs appeared to be broken off, not burned but I could be wrong about this. 2N3055 was the only original Power Transistor left. You guys would probably have a better handle as to why the leg would come off the MPS-U45. I would hate to put new on and have them fail immediately. Waiting for MPS-U45's to arrive.

I have an auto striper that can be set to a specific length of insulation to be removed. I set this to the Molex Terminal Crimp 08-52-0075 specification. I crimped them using Molex : 63811-8200 - Premium Grade Hand Crimp Tool for KK 2.54mm Crimp Terminals, 22-30 AWG. I gave each terminal a firm tug before inserting them in the plug.

Tom

I found a used MPS-U45 in my Gottlieb goldmine of parts. All is working as it should. Whew! - Tom

I just ran in to this twice now in three games. I had a ball locked in the lower and upper playfield Captive Hole. I drained during ball 4 and after the Captive Hole ball was released to drain, ball four did not finish and so it would not advance to ball 5. I checked both trough contacts and they were operating as they should and gapped properly. In the morning I will check the contacts in both the lower and upper playfield Captive Holes.

Tom

UPDATE, Wound up that the return contact was was making a poor connection on the contact leaf support plate rather than the contact itself.

Games been playing well. It just started this after replacing the bulbs with LED's. I have a nuisance 10 points being scored when the playfield gets jarred. Right away you would think the SW 34's are gapped to closely, but no that's not it, I isolated all of them. It could be SW 34's circuit but not the contacts of the SW 34's. I don't know of another place where you score 10 points though.

NOW: To add frustration my wife was playing it two nights ago and non of the drop targets on the upper play field are resetting. I'm guessing a fuse, driver transistor of missing CPU signal. I'll have a look at those and update. - Tom

Problem with the drop targets. Neither the 5 Pos. or 4 Pos. Target Bank will reset. The F-14 2 amp Slow Fuse is open. After replacing the fuse the 5 Pos. Target Bank stays energized and the 4 Pos. Target Bank does not reset. Anyone see this before? I just checked the Diode on the 5 Pos. Target Bank and its good! Same on the 4. I guess Ill check the transistors for Sol. 1 & 2 on the driver board too.

Thanks for your help, Tom

Driver Board findings

Sol #1, 4 Pos. Drop Target Q60, SE9300 (NTE263) TO220 Package PNP. From Base to Collector, 2.039MΩ. From Collector to Emitter, 2.239MΩ. With reversed leads its open. GOOD!

Sol #2, 5 Pos. Drop Target Q58, 2N3055 TO−204AA (TO−3) Package NPN. Base to Emitter, 258.8Ω. Emitter to Base, 259.0Ω. SHORTED!

I do have one of these on hand so I will be replacing and reporting on findings.

Presently I am guessing that Sol #1, 4 Pos. Drop Target would not reset because the short in Sol #2, 5 Pos. Drop Target Q58, was interrupting the logic to allow for this? Maybe puling down the +5 in the power supply due to this load?

Tom

UPDATE: I replaced Sol #2, for the 5 Pos. Drop Target. Its Q58, a 2N3055. That was the only issue. Sol #1, 4 Pos. Drop Target resets as well now.

- Tom

This is what I isolated on the upper playfield -
TEN-POINT SWITCHES
• Score 10 points.
Kicking Target
Kicking Rubbers

Actionable Item:

I will isolate any of these on the lower playfield too (3, Sw. 72's).

In the Black Hole Instruction Manual, in a separate column I found this 10 Point Sw I didn't see before -
TEN-POINT SWITCHES
• Score 10 points.
• Closes gate except during multi-ball.

Actionable Item:

I will need to investigate just how the 10 Points is switched (It seems like in a non multi ball scenario if lamp L39 is lite and roll over SW 35 is closed, then the gate solenoid allows the gate to be closed a contact comes in to provided the 10 Points).
Anyone have any further ideas on how to track this down? - Tom

This made no change. If I walk anywhere near this machine it will begin to score bunches of 10 points. I turned up the volume and this began scoring as well. The only thing I can add is when the play field is raised it become less sensitive as the pitch increases. I did make sure all plugs are tight. I may need to physically trace these conductors to find out how the signal is being introduced. The prospect of doing this is not a pleasant one. Any ideas to avoid this are appreciated. - Tom

One of the 10 point contact's support leaf was uninsulated making an intermittent contact with the apposing leaf. I bent back the support leaf allowing it to again support the contact and I used some card stock and cut out an insulator.

Trouble Spotting This: The support leaf's view was obscured by the surrounding components and wiring making this a challenge to pinpoint visually.