Have a project Space Station, so now in the club, and I am having a couple of issues with solenoids and GI.
- None of the solenoids or flippers will fire
- the backbox GI is working, as are all of the playfield insert lights.
- none of the playfield GI is working

The MPU just came back from being repaired, so hoping that is not the issue.
- on the power supply board I am getting +12.2 v at TP3, -14.1v at TP4 and 5.1v at TP1.
- I tried to jumper Q8 transistor on MPU to get the A/C select relay to click, but nothing (as I read in one of the guides).
- the transistor itself tested OK.

If the relay doesn't click, does that necessarily mean it is bad, or do I have an issue earlier than the relay?

What should I be checking for?

You were right on, one of the gi relays was burnt/non-functional and once I replaced it with one of the ones that worked, the GI worked. Not sure condition green is kicking in though.

Will look at the BR for the solenoid issue.

Thanks.

I believe the BRs are good. I have it now narrowed down to perhaps the ground on the special solenoids. When I look at the manual, everything that isn't working is listed as special solenoids 17-22 (and the flippers). There is voltage at the flipper coils, and I can fire the right dock kickback by grounding the transistor on the MPU. The MPU board was sent for repairs and tested there, so I am hoping that is not the issue (but can't be sure).

I am not sure where to go next. Thoughts?

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Do you mean system b board?

Don't think it is wiring issue. I can fire the solenoids if I ground the transistor on the mpu. For example if I ground q73, it fires the right pop bumper. To me,
that would eliminate the mpu connectjons/wiring and the auxiliary board connections.

Am I correct in this?

Where do I go next? What should I be testing next, something on the mpu? What causes the mpu to send the signal to open ground for the solenoids?

Here are some photos. The place that serviced the board said they tested it in a shop Space Station.

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There was some battery damage when I got it. Tried to clean it up the best I could.

OK, so I check u45. As you say, in attract mode:

pin 1 - low
pin 2 - high
pin 3 - high

When I close the switch to the pop bumper by pressing the switch with my finger from the top of the playfield, no change.

When I go into diagnostics, no noise from flipper and no change to state of pins 1-3 when I close switch again.

Next?

Pin 6 starts high and does not go low when a game is started. Using a logic probe.

U56 pin 5 - low
U50 pin 11, 12 & 13 - all low, but did have problems getting readings. I may have to clean these a bit or see if there is corrosion.

All low. But as I said in the other post, I was having troubles getting readings from the pins. I also noticed that once when I was trying to get a reading, the probe slipped and crossed pins 11 and 12. When that happened, I could hear K1 click. So, I am thinking from that that K1 is likely not the issue?

Any next steps guys? Trying to follow the schematics, but still learning.

I have some parts to rebuild the power supply on order, capacitors, etc. The voltages read fine on the test points, but thought this would be preventative maintenance. Any chance the issues are power related, or are we thinking chips on the board, keeping in mind that I was told the mpu was tested on a space machine before being sent back to me.

Thanks.

OK, we are definitely getting somewhere. I reflowed the pins on U50. When a game is started, pins 10 and 12 of u50 are low. Pin 11 I cannot get reading from.

When I keep ground on pin 11, the flippers, pop bumpers, etc all work. That's the good news.

The bad news is that while doing that I may have fried Q75 and / or Q74, as smoke came out of that area. Obviously crossed pins or something. That area around that transistor was already blackened, so it must have burned in the past as well. Not sure if that is related to my issues or not.

Obviously I will replace Q74 and 75. Should I just replace U50, or do we think the issue is elsewhere?

Thanks in advance.

I replaced U-49 and U-50.

Now when I test U-50 with a game started I have the following:
- pin 10 and 12 are low
- no reading from pin 11
- when i ground pin 11, K-1 clicks

Not sure what you mean by cutting pin 11 in half. I would expect it doesn't matter since I replaced U-50 now.

Are you still thinking U-10 may be bad?

And am i reading the schematics correctly that pin 11 of U-50 is fed by pin 19 of U-10?

Was thinking the same. Just before slipping out to work I checked for continuity between the two with the board still in the backbox. No continuity.

Turned game on and checked pin 19 of U-10 and is showing low. Is that what it should be?

I will have to pull the board out and check what the continuity issue is. If the trace is damaged, what is the best method to repair? I know you could run a wire between the two, but is that the best method? Hate to get into the hacks too much.

I will likely have to take another one from the front, more glare than I thought.

I was trying to run some continuity tests, and I can't tell where the trace from pin 19 of U-10 exits the chip. Seems like it is under the chip where it enters pin 19.

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Hey Grumpy, I am at a loss here. I just can't see where the trace for pin 11 of U-50 goes or comes from. I removed the socket to try and see it better, but I don't see on either side a trace going to the pin. I have attached pictures. Any ideas, am I just missing something obvious??

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Correct you are Grumpy, my apologies. So, I had to remove U-49 to see the trace. Once I did I found I had 2 failure points. One a long line with a scratch in the line breaking continuity. The other right at U-49 (see 2 points on picture).

So, I know the 2 issues (thanks again for your patient help). What is the best way to repair? Both are thin traces of course, with one of them going under a chip once I replace U-49 socket. Relatively new to board repair (as you may have guessed).

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Making progress for sure. Once the traces were continuous, pin 11 of U-50 started reporting a reading. That brought to life the flippers and slingshots! So, power is now flowing to the special solenoids. What isn't working yet are the pop pumpers and right ball lock. Have to try and trace down what is happening with them, and why they aren't getting power.

Both low.

So, yes F3 is part of the story. It is blowing very quickly. During one test I could ground Q79 (lower pop bumper) and Q73 (right pop) and both would fire. When I grounded Q77 (middle pop), the fuse would blow.

I removed the board and checked the transistors, pre-drivers, traces, etc. and didn't find any shorts.

I then checked under the playfield for shorts, crossed wires and such and didn't see anything. Continuity back to the board (ground) was fine and was very close to 0 ohms. Even replaced the diode on the coil to see if it may be an issue.

Replaced everything and F3 fuse blew within a few seconds of starting a game.

Thoughts?

Coils all read the same, just around 4 ohms. Diode was replaced on center pop already. Adjustments are fine.

Tried to diagnose a bit more, and this may help. I disconnected the left/middle pop bumper (which I thought was the issue). Once I start up the machine, the bottom pop bumper immediately fires and stays on until the fuse blows.

I then disconnected 1J19 from the MPU. Games starts, and nothing happens. As soon as I reconnect the plug, the bottom pop immediately fires, and stays on until the fuse blows.

Is this telling me anything?

Did some logic testing. Q76 and Q77 are giving me the weird readings ( as compared to the others). Going to go ahead and replace them both and see what happens.

U-50 tested as you suggested below.

I checked the zener diodes, and a lot of them seemed to have been cut ( to test I assume ), but never soldered back correctly. So, I just replaced them. That with a couple more replacements and the special solenoids work, except the right dock.

Wiring is OK to Q75, as I can ground the resistor and it fires. Am I reading the schematic correctly here:

U45 pins 11 and 12 should go high to fire (correct?). What I have on coil test is:
11 - low
12- high

So I trace back, and here I am not sure I have it correct, U44 pin 23 feeds into U45 pin 11?

What I get is all three lights coming on in logic probe.

Then, does U51 pin 2 feed into U44? I don't get any reading on U51 pin 2. Am I reading the schematic correctly?

Another issue I have (among a couple of others), is that when I boot the machine, it will only boot every 5-10 times I turn the main power switch on. Hooked it up to a desktop power source and same thing. I thought I had read that one of the pia chips may be at fault, but can't find the article again. Thoughts?

On

Perhaps a stupid question, I have been wondering, what does "sign me up" actually do? Do the group moderators keep a list of people signed up?

Thanks to GRUMPY and ajfclark I have vastly increased my knowledge of board repairs. On my space station they have been helping me with, I am almost completely up and running. Summary of repairs:
- fixed 2 broken traces,
- replaced several transistors,
- replaced zener diodes that had been cut (for testing I assume) but no reconnected properly
- replaced a couple of ICs and a PIA

Only one issue remains. The board doesn't always boot (usually have to switch on/off 10-15 times before it will). Not a voltage issue from power supply, as same thing happens when powered by a desktop power supply.

When turned on, the voltage LED lights, but nothing past that. No diagnostic flashes. Sometimes when turning on I will get random sounds or a coil firing for a second.

Thoughts of how to diagnose this?

Yes. It didn't make any difference.

I may have figured it out. When I press on either U41 or U42 during boot up, it will start every time. The flexing of the board appears to be making a connection that isn't quite proper without flexing. One of them is sockected, one is not.

I will replace the unsocketed and reflow the socketed one, and see if one of them is the culprit. Does that make sense?

Can you explain why this is your opinion? It seems to go against a lot of other advice from people. Not criticizing, just wondering about your reasons.

Makes sense. Thanks for the explanation Grumpy.

Still working on a Space Station with boot up issues. It will only boot randomly. What I have just found is that if I leave the machine on for an hour (in the state where the cpu didn't boot), when I come back to it, it seems to boot fine. So, something seems to be heating up and then making the required connection for the cpu to boot. Does that point to a cracked solder joint somewhere on cpu, or a power supply issue?

Voltages seems good, and power supply caps have been replaced.

I am still struggling to get my Space Station board fixed. With Grumpy's and others help I had it to a point where it would boot and work fine, but only after the machine was powered on for 15 minutes, then would boot everytime. Also sometimes if I flexed the board a certain way it would boot.

I thought that was pointing to a cold solder, so I was looking for cold solders and reflowing some of the pins on the mpu. Now of course i cannot get it to boot at all, just the 5v led comes on. No flashes of the diagnostic led. Kind of lost now and not sure where to start.

So, I thought I would hook it up to an old desktop to bench test.

Question, is this normal? When I test the voltages of the power supply, I get the normal 5.1 volts. As soon as I attach it to the MPU pins, the voltage drops to 4.7, and at that level the board will never boot. Is that normal? Am I missing something?

Any suggestions on where to start with getting board to boot would be appreciated, as well as the 5 volt question from the desktop computer power supply.

The only chips that have any extra heat are the 2 6802s at u15 and u24. They are not super hot, reading the highest on u24 around 100-105 F, with u15 slightly cooler. About 10F more than any other chips.

GRUMPY=smart.

I was using 24 gauge wire, and once I switched to 18 gauge the voltage went from 4.7v to 4.95v when connected to the mpu. I am assuming that the 4.95v will suffice to boot a board?

Now where is the best place to start bench testing?

Yes, but no -12v as the repair guide I was reading suggests.

I am wondeing Grumpy if you can point me at a starting point to get my Space Station board to boot? A quick review:
- board was sent away for repair, but the repair job was less than stellar
- board would boot if I left it on for 10 minutes then re-powered on, or if I flexed the board. Everything was working once it started.
- I was trying to track down the booting issue thinking it was a cold solder issue somewhere, so I reflowed pins in the u2 / u3 area
- afterwards it won't boot at all now, and have it on bench trying to diagnose
- only 5v led comes on, not the diagnostic or blanking leds

Following the Repairng Williams System 11 Pinball guide, I have checked:
- good 5v / 12v to the board
- u25 was changed to nvram
- using logic probe, u15 pin 39 seems to react properly (both high and low lights are solid)
- grounded pin 40 of u15 to see if reset circuit resets, nothing
- checked the PIA chips by testing with DMM pins 2-17, and all read in the .4 to .8v range, and all get +5v at pin 20 when powered on
- checked u11 and u13 with DMM, pins 1-9, 11-19 seem to read fine
- replaced the 4 caps (including c30) on the mpu

What should I be checking or replacing next? Thanks in advance!

No I haven't touched them (assuming you are talking about u21 and u22). Should I?

Sorry, right. Not sure what I was thinking when I said that. No, they are socketed, but I didn't touch them.