New Information

New information on the quest to fix the sound problems on the Star Trip.

According to this info,

the SSU-1 is driven by transistors on the solenoid board (SDU-1) where the MPU board selects which sounds to play, triggers the appropriate driver transistor on the SDU which in turn selects the sound to be played on the sound board. Sounds are tested during the solenoid test where each of the four sounds should be played once for each respective solenoid transistor. The other SSU boards are driven directly from the MPU board, freeing up solenoid transistors for other game functions. For SSU-1, each of the four sounds is triggered by one of four transistors on the SDU, specifically, Q3, Q10, Q12, Q13. These are connected from J2 on the SDU, to the 8 pin pigtail that hangs off the SSU-1. The pin mappings are as follows:SDU J2 Pin -> SSU-1 pigtail Pin

2 (Q10, Red-Vio wire) -> 2

5 (Q12, Yel-Green wire) -> 5

6 (Q3, Brn-Blu wire) -> 3

7 (Q13, Grn-Blk wire) -> 4

Which means I have been looking at the wrong board, I've been looking at the main processor board when I should be looking at the Solenoid board. This makes sense as I have had to replace several transistors on the SDU already, looks like I may have another bad one!

This is good news and gives me hope for a real fix!

More work on the Star Trip sound problem

I spent some time tonight looking into the sound problems on the Star Trip table. The issue is that everything works fine for about 3 minutes then a whine begins and never ends. The sound effects try to play but the whine is loud and overwhelms everything.

After reading about some different ideas, I started by reheating all the solder joints on the main board. Not everything, but the ones that looked suspect:

Following that, after reading about problems with "Scanbe" sockets, I pulled the chips off the main board one by one and verified I did not have Scanbe sockets:

After putting it all back together - the same problem. Runs fine, works perfectly but the whine is teeth-rattling after a couple of minutes!

Since the problem occurs only after a few minutes, I reasoned it has to be either a capacitor or some connection that fails as it heats up...note to self, as I write this it occurs to me it could be a chip that fails as it heats up as well.

The next step was to see what board the problem was on: MPU (Main Processor Board) or MSU (Main Sound Unit)

While the game was on, I very carefully opened it up, hoping not to have another self-created disaster. Then unplugged the sound board. My reasoning is that if it is heat-related, unplugging the sound board and letting it cool while the main processor is working will tell me.

My assumption: after 5 minutes, when I plug the sound board back in:

1. If the sound continues, the problem is in the main board
2. If the sound is not there but comes back after a couple of minutes, then it was in the cooled down sound board.

After several minutes, I plugged the sound board back in and the whine was still there. It appears the problem is somewhere in the Main Processor Unit...sigh

Next step is to try and decipher the schematics enough to figure out where the sound-related components are and really dig into them.

Sound problems with the Star Trip

One of the things I have been struggling with is the sound on the Star Trip pinball.

With the sound board removed everything works correctly. With the sound board connected, I get 6 flashes on the main board, then the sound goes wacky!

According to research:

No seventh LED flash means replace the PIA at U5. Also try disconnecting J1 from the MSU board and rebooting. If the seventh MSU LED flash is seen, the problem is on the MPU board.

Since I only have 6 flashes and when I disconnect the sound board everything looks ok. It seems my best bet is to replace the chip at U5.

Time to go and find one

Problems with the Globetrotters

Took a look at the Globetrotters today. Opened it up and took a close look at the boards. I havn't pulled anything out yet but the power board does not look good. Looks like something burned or blew up or something!

A breakthrough

The Star Trip table has had to wait for a couple of months while I fixed the self-inflicted problem on the Hot Tip table.

But over the 3 day weekend, I decided to re-tackle it. First I tested it to be sure it still had problems, sure enough turning on the solenoid self-test caused the fuse to blow.

Disconnecting the left drop target allowed everything to run. The transistor associated withthe left drop target solenoid is Q4. So I unsoldered the transistor....again......

and tested it.....another dead transistor!

I soldered on a new one, plugged everything back in...

The fuse blew again.

So I did some cussing, then finally settled down and started trying to figure out what was wrong. I finally came up with what I thought was the problem, the diode on the replacement solenoid was pointed the wrong direction.

 There are 3 solenoids, one for each drop target. All use a dual-wire on the left and a single wire on the right:

however, after carefully checking, the diode on the newly replaced solenoid points the opposite direction of the original. Which means either I need to connect the wires on the opposite side or switch the diode to the other direction or the solenoid is going to push in the wrong direction because it is not the right part.

I opted to reverse the wires. Then I unsoldered, tested, verified it was dead, replaced and resoldered the transistor, plugged everything back in...

The fuse blew again.

My wife came out to ask about the cussing. I demonstrated how everything was not working. She suggested checking everything piece by piece and asked about the soldering on the solenoid. I explained how that wasn't the problem and proved it by connecting the multimeter to it...

The multimeter shows that the solenoid is shorted out. So it was time to use my only spare and solder in the new one.

Before I turned it on I finally wished up and decided to replace both the parts at the same time. So the transistor was unsoldered and a new one soldered in. Then I turned it on...

Everything worked!

Back up and running

After self-inflicting damage to my Hot-Tip table, I ordered a replacement solenoid for the right flipper.

I pulled the damaged solenoid assembly...

And put the new solenoid in

Then put it back into the table and fired it up.

Everything works but no right-flipper.

Checking the circuit, the wiring is pretty simple. There is a blue wire that runs from the fuse directly to each flipper solenoid.

I checked the voltages, I had voltage at the fuse, voltage at left flipper and nothing at the right flipper.

After scanning the circuits for some kind of problem I went back to the solenoid. The solder on one of the posts did not look very good so I resoldered it.....and lo and behold, it worked!

and the light has been replaced, so the table is back in operation!!

whew

Self-inflicted wounds

Apparently, the source of my problems is.....me

The Hot Tip table has a couple of burned out lights. I thought it a bit difficult to count which ones were out in the series so I came up with the brilliant idea to leave the power on and in light-flashing-mode and open the table.

I lifted up the table but while shifting my grip I managed to set the partially extracted table down onto the metal bar.

POW

smoke curled out and the table went dead... really dead, not a light on it.

I checked the circuit breaker in the panel - it was fine. I opened the back and checked all the fuses on the power supply, they were fine. Looks like it was time to toss it into the garbage.


Before I retrieved the dolly, I started thinking about power. I have nothing lit at all and all the power supply fuses are low voltage - 5 and 28 volts. There must be a house-current fuse somewhere.

I followed the power cord into the cabinet and where it snaked around until I found another fuse, hidden back on the side of the lower cabinet. It was blown...off to the hardware store!

While looking around, I wondered if I had shorted and melted anything, I checked the wires on the solenoid that was the problem and they were ok, but then I looked at the solenoid itself.

I must have set it down harder than I thought as I gouged a divot into the windings of the solenoid....sigh, time to replace one of them as well...

and the light still isn't replaced...sigh

Cleaning the dropdown - part 3

This is turning into the part that will not live....

as documented last time I purchased a replacement solenoid and transistors, I soldered the transistors into the board, wired the solenoid up and tried it out. Nothing worked and now there is a whine, even after pulling out the transistors and solenoid...

After spending quite a bit of time looking at the solenoid board and trying things I found the problem appears to be in the sound board. At least when I pull the sound board everything starts working again.

However..... after soldering the transistors back in again...

All of the solenoids stopped working.
More checking, the fuse under the playfield is blown. And it blows every time I connect the replacement solenoid back in.

Time to find out if that was the right transistor.

The saga of the knocker - part 1

One of the interesting pieces of a pinball game is the "knocker." This is the device that makes a loud distinctive sound when you match and get a free game.

On the Star Trip, the knocker solenoid was fried. I found this some time back and had disconnected it (removed the wire) - now it was time to try and fix it.

Step 1 - removal

I pulled it out of the cabinet. It is strange looking compared to the other solenoids:

The dark band around the solenoid shows it is burned. I took everything apart. it has some unique features. There is a long plunger with a copper end on it and the plastic tube sticks out much further than any other ones I have seen.

Checking inside the tube, it looks like there is a wad of gum in there!

After checking with the experts, I found out that:

1) the "knock" sound is the plunger striking the bare side of the metal assembly
2) the "gum" is actually a severely melted plastic tube
3) I will need to replace everything but the metal

Off to order more parts!

Finally - a success!

After quite a bit of trying, I finally achieved some success!

 

Let me back up two months....

 

When I purchased the Hot Tip table, one of the solenoids was on continuously. I ran some diagnostics and even went so far as to unsolder transistors that I thought might be the problem and then test them. All the transistors tested ok so I still have no clue on why that particular problem is there.

 

However, after soldering the transistors back in, I put the boards back together and although the original solenoid still was in the same state, now the flippers would not work.

 

I pulled the boards again, double-checked that I had not shorted anything, reseated all chips, reflowed the solder on all the parts that I had touched....nothing.

 

The flippers have a very limited logic, they are not computer controlled as back then the computers were not fast enough, so the circuit for them is very simple on the schematics. Trying to figure out where the problem might be on the actual boards based on the schematics is really tough though and I have pulled the boards about a dozen times trying different things and checking ever more carefully.

 

Fast-forward to last night. I tested the fuse underneath the playfield. It should have had 28 volts on it since flippers, like all solenoids operate at 28v, but it did not, it only had about 5v......

 

.....great - some kind of voltage problem.....

 

 

......But it is really strange that it happened while I was pulling boards......

 

 

As I prepared to get out the multi-meter to start trying to follow voltages on the power-supply, I noticed a lone wire hanging inside the cabinet. It had a simple press-connector on it and was not connected to anything.

 

Was it supposed to be like that? or am I missing a connection somewhere...

 

After pulling up the playfield and looking around I found the other end of the wire, with the matching connector on it.  I connected them....

 

 

Low and behold the flippers started working!

 

Why every single other connection on the table goes through a board or a multi-wire connector and this one lone wire is all by itself I have no idea.....but at least the flippers work!

 

I have successfully made it back to the state the table was in two months ago!

Cleaning the dropdown - part 2 (disaster)

Time to own up. I have made a totally stupid mistake and have screwed up my table.

I took apart the dropdown and cleaned it. Afterwards the fuse blew.

After considerable head-scratching, I discovered two things:

1) I did not take good enough pictures. It seemed easy to take a couple shots and start taking it apart, but when it came time to put it back together the lack of pictures made it almost impossible to figure out which way the tiny lip was oriented on the sleeve or which wire went where.....I had lots of pictures but the wires were out of focus in every one.

2) after taking my best shot at putting it all back together and wiring it all back up and powering it on, I found I had put the solenoid in upside-down.

Which means it was wired backwards!

Naturally it pops the fuse. I took it apart, put it back together the right way and tried again. Still blows the fuse.

Checking the diode on the solenoid - Its fried....sigh.... so I ordered a replacement.

It finally arrived today and I eagerly soldered it in and turned the table on....it blew the fuse again!

...sigh...

So I disconnected the new parts and the table worked just fine.  I spent considerable time digging around in the parts looking for a short or something, without success. Finally I started checking voltages, I found that the wires to the cleaned dropdown assembly had 28 volts on them all the time instead of being switched.

I am pretty sure that means I have shorted out at least one transistor on one of the boards, possibly a chip.

Oh yaaa

Cleaning the dropdown - part 1

On the Star Trip pinball table, one of the dropdown targetswill not drop. When the ball hits it, it will usually not drop at all, sometimes it will slowly sink halfway or if I push it it will go down where it is supposed to. The other two work just fine so it was definitely a problem with the one unit.

I thought it might be a bad spring, not strong enough to pull it down and since the others were working this seemed a perfect project as I could compare the good ones with the bad one.

So I set about pulling the mechanism off the table and finding out what was wrong:

At first check, all looked ok. Nothing was obviously broken or bent out of shape.

After unsoldering the connections, I took it apart:

 

It wasn't until I had it all apart and moved things around that I found what I think was the problem. The spring seemed ok and was about the same tension as the other springs, but the whole mechanism was incredibly dirty!

This is the plunger that supposedly slides easily through the solenoid coil, it should be a shiny smooth polished rod:

My polishing tumbler is still on order, so I sprayed everything with engine degreaser and wiped it all down, then reassembled it.

It seemed to work smoother and I eagerly put it back on the table, soldered the leads back on and fired up the table....

Only to have the fuse blow out immediately!

I checked the solder connections, everything looks good....but now it doesn't work...sigh

(more to come)

A few problems with the Harlem Globetrotters

I have done an initial check of the Harlem Globetrotters. It is in pretty poor shape:

The box itself looks to have typical old-wood problem, corners are splintering - but at least it seem solid

The electronics don't work at all. When it is turned on a few lights come on and thats it, no sound, no movement, no nothing.

The playfield is also in pretty poor shape - in addition to the missing graphics in heavy-wear areas there are some more serious issues:

This shows a representative piece of the playfield, much of the paint/graphics are cracked on the wood.

The plastic isn't much better:

The edges are scalloped, cracks around the mounting bolts and even warped sagging pieces - did it sit in the sun or under a heat lamp?


Other problems are around the bumpers, missing and bent ones are in several places:

This one is a bit tough to see but the support pin in the center is bent inward and pushing on the plastic

Also, almost every single slot/hole in the table has a worn out spot where the ball went - this table has seen a LOT of use!


On the positive side, the backglass is in great shape!

it is virtually perfect with only the beginning of paint coming off in the corners around the scoring boxes.

So this one is going to be a lot of work.....

Success (at last)

Success at last!

After finally (2 months in!) discovering that there was another fuse - cleverly hidden by the Game Plan designers under the playfield rather than where all the other fuses were:

Only to discover it blows immediately when powered on.

Then spending all night carefully unsoldering each and every coil (and diode) and testing them all good.

Finally turning it back on (with all of the coils still unconnected) and the fuse blowing AGAIN!

I posted my results and Viperrwk calmly pointed out that there was one more coil.

Down in the cabinet, underneath the ball that rolls back and forth to prevent tipping the cabinet, there is a coil that fires when the match happens - that big "knock on wood" sound you hear when you are lucky enough to get a free play.

I located the coil and unsoldered it. It does not test as good as the others (2.8 ohm instead of 5.5 or 8)

With ALL the coils now disconnected, I put a new fuse in....crossed my fingers...and turned it on.

The fuse did NOT blow!

woohoo, real progress at last.

Of course it could be that it isn't blowing because there was now nothing at all on the circuit. So I connected three coils, crossed my fingers and tried again.

the fuse did not blow!

and, the coils worked. In diagnostic mode they fire one after another and each one I had reconnected worked just fine.

It appears I have real success. I may be able to put it back together and start playing it!

A green world

I just went to see Mad Max in the theaters yesterday. It was quite the action-packed movie!

One thing that really struck me as I walked my dog at the park was how green and beautiful everything is - the movie really showed how difficult and horrible the world would be if it is destroyed by ignorance and greed.

I am quite sure that was not the reaction the writers, producers and directors were anticipating, but it sure made me stop and appreciate just how beautiful our green world really is.

Tiny progress

A quick post to report a tiny amount of progress. I finally discovered that mounted to the underside of the playing table on the star trip pinball is another fuse!

And there was no fuse in the holder. Putting a fuse in, it blew immediately but this is a much different problem then thinking I had a logic problem on the driver board. So a tiny amount of progress!

Star Trip Main Processing Board testing (pics)

While I wait for answers about my questions on the AC leakage from the power supply capacitor. I thought I would turn my attention to the main processing board. I just got a new testing tool, an Atlas DCA55 which says it is easy to use. Just connect it and it figures everything out.

I tried checking the diodes but it is unable to test them while in the board. I'm not ready to unsolder every component and check it yet, so I turned my attention to the transistors.

I checked the first one, and it shows "transistor" and that all is good!

The second one says it is not a transistor but is in fact a diode network...hmmm

with the third one we are back to a transistor again and it is ok.

It thinks the last one is a LED or diode...bizarre

According to the schematic and parts list the bottom 3 are supposed to be the same transistor and the top one is a slightly different transistor. So I guess I will have to unsolder #2 and #4 from the board and check them isolated, it is possible the board connections are messing up the reading.

edit: the manual specifically says it cannot check transistors while in circuit....before i start pulling things off the board at random i think i will look around some more.

While checking the transistors, I noticed the board has a lot of corrosion:

Apparently this is pretty common as the battery they used to store the high scores leaked acid vapors over the years.

After looking around some more it is apparent this board has already been repaired once:

the battery has been removed and the area around it looks to have been sanded down (presumably to remove the corrosion) and even a wire was soldered in where a board trace had failed. So hopefully all of those fixes are still good!

Power supply woes continue

after reading some more about the Star Trip power supply, one of the suggestions was to check the large 11,000 mfd capacitor for AC leakage. According to the article there shouldn't be more than 0.2 volts AC.

After connecting up the multimeter, mine reads 30 volts!

 

So either I am doing it completely wrong (very possible!) or that capacitor is completely destroyed (very possible!)

Off to post more questions...at least I am learning about electronics

A new table - harlem globetrotters

Through the generosity of a friend, I was able to purchase a 1987 Harlem Globetrotters pinball table. The table glass is in excellent shape, the table surface in medium shape with some graphics worn off. The electronics currently do not work, when I power it on a few lights come on and thats it. No sound, no movement, no bumpers.

Another project!

Testing the power supply

After purchasing new probe tips for my multimeter I tested the power supply at the connector to the solenoid driver.

I am getting power where it is supposed to be but the voltages are not right:

when I check pins 4 and 1,2 ... I get 12v which matches the circuit diagram
pins 4 and 12 give 33vac instead of 24
pins 4 and 13 give 27v instead of 24
pins 4 and 15 give 5v. Matching circuit diagram

So its off to the forums to ask if this is the problem or no big deal and it is within tolerances

Power Supply Voltages

After tearing out the power supply (P/S) and discovering that it was mounted on a piece of plywood I did some more asking around.

It turns out that the very first generation of these cocktail machines used a handmade P/S, so there isn't anything inherently wrong with my unit.

I was able to get a circuit diagram and parts layout that showed what the fuse sizes were and the expected voltages across them. So I put the P/S back into the unit and checked power.

4th from the bottom was supposed to be 12V, the meter confirmed it was.

3rd from the bottom was supposed to be 7V, my meter shows 3.5V instead.

 2nd from the bottom was supposed to be 28V. I've got the meter on 25V range and it is showing only 14V.

So I have something actually wrong with the power supply circuitry, not too surprising considering it is almost 40 years old, but it complicates things quite a bit. Perhaps this is the only problem with the table though and once this is fixed everything else will work!

Power supply problems

 

I've been really pulling my hair out over the "Star Trip" cocktail table power problems. I think there is a power problem of some kind because none of the solenoids will fire. So either the whole board is shot or there is a power problem of some kind. Checking the power seems an easy first step.

 

But the cocktail tables are a major pain to work on because they are so deep. To reach the power supply board down on the ground level I have to bend over the lip and way down in, trying not to touch anything or bump the brace I have holding the table up.

 

I purchased a repair manual from ebay and it has lots of helpful information on what voltages should be seen on what test points on the power supply board. Unfortunately it did not provide an actual diagram of the board and I can't find them.

 

Finally I found some information on another repair site. And I think I have discovered why I am having such a problem. This is a picture of a standard Star Trip power supply board.

 

 

 

And now, my board:

 

 

Notice any difference? Yes....my power supply "board" is an actual board. Someone removed the board (with its test points) and mounted the power supply components onto a piece of plywood.

 

 

sigh

More solenoid frustration

I made limited progress on finding what the problem with the solenoid was.

After downloading the user guide, it explained how to run the diagnostics. I ran the switch diagnostics which told me that none of the switches were faulty. I then ran the solenoid diags and the solenoid was on the whole time as the other ones fired one at a time.

The process gave me 2 important clues.
1 - during the switch test the solenoid was not on. This tells me it is not a short as a true short should have powered the solenoid even then.
2 - during the solenoid test the solenoid was on all the time. If it was shorted to a couple of other solenoids it should have powered off at least once as they all fired one at a time.

Based on this it is most likely something on the solenoid board. When the board is unpowered (during the switch test) the solenoid is off and when the board is powered tne solenoid is on all the time.

Hopefully it is an easy to replace transistor!

I labeled everything and pulled the board, then ran the simple multimeter test on the transistors without any success...sigh
So I have ordered a real testor. Keeping my fingers crossed!