Im leaving the 120v jumper in place for now.

All of the game problems seem exaggerated.

This might help to narrow down the culprit.

I played a game to check out its current staus.

The game lost the ball count on ball one.

Kicked out an extra ball on ball 2.

Played 4 balls on glider craft.

Mode ended early with 4 balls in play.

All 4 balls exited the outhole.

The game couldnt clear them and they all stayed trapped in the outhole.
My modified coil still isnt strong enough to clear 2 balls. Ill work on this a bit more and get it to clear 2 balls at once in test.

Putting a 23-800 coil seems extreme.

Possibly the "blue" wrapper coil thats listed at 42 ohms will work well enough?
4 balls in outhole (resized).jpg

Today Im going to manually test the game modes to see if a switch or mode can shine light on the problems.

The plan is to start multiballs and remove the balls in play as they come out.

Manually trip the switches with a ball and see if I can get the mode to end early while dropping a ball into the outhole once in awhile to simulate game play.

Also see if a mode times out.

In theory a mode shouldnt time out until there is only one ball left in play.

If something wrong happens, I should be able to reproduce it.

This should be interesting.

Before getting into something exotic, I was thinking about the dramatic change that the game went through by changing the power jumper.

Maybe its already in a low power state?

Are the main fuses loose or corroded?

Time to check the power box MA-1928

stargate power box (resized).jpg

5 amp fuse holder (F2) has a cracked nut and the top is wiggly.

The fuse is loose in the holder and doesnt firmly touch the bottom contact.

broken nut (resized).jpg

There doesnt seem to be a Gottlieb fuse holder per se.

The holder has Buss HTB molded on to it. Searching for that yielded good results.

This one is perfect:

amazon.com link »

I bought a couple at West Marine in reno.

fuse holder (resized).jpg

Evidently boats use them all the time.

Its a perfect fit. Although it inserts from the bottom instead of the top.

I doubt that this will change the game much.

All Done:

installed bottom (resized).jpg

installed top (resized).jpg

Fuses fit snug and the tops are NOT wiggly!

Much better than the 28 year old crispy ones.

The power box looks great and un-tampered with.

Fuse holders are solid!

Still waiting on Pop-bumper parts to get those sorted out.

Meanwhile my Aux driver board arrived!

Im certain it will have little to no effect on my ball count issues, but freshening 28 year old boards can only be a good thing.

old board:
old aux driver (resized).jpg

new board:
new aux driver board (resized).jpg

2 min install and it works perfectly!

While waiting for parts, I noticed that the pivot targets "squeek" and one has a cracked switch.

I "do" have those switches in stock!

Its super easy to lube the pivot points, and replace the switch. I might as well replace the coil sleeve while Im at it.

left pivot target (resized).jpg

Oiled all the pivots on both pivot targets with a tiny drop of oil, but not just any oil:

Super lube precision oiler part# 51014. Dries out leaves no gummy residue, its primarily PTFE (teflon):

https://www.homedepot.com/p/Super-Lube-7ml-Precision-Oiler-Oil-with-Syncolon-PTFE-Lubricant-Per-Each-51010/202932717?source=shoppingads&locale=en-US&srsltid=AeTunco7CTEEzMQcBZXPE5Yw6vsCWLf4RVZH0q7uH2Nw_0JeFNrIKlr_lZw

Or use any "dry" lube. this works well.

oil pivot points (resized).jpg

Squeek and roughness all gone. Works buttery smooth now.

New switches both pivots.

F#ckn Marco sent one that was missing the bolt plate.... Its ok just move the old one to the new switch.

new switch missing part (resized).jpg

smart mounting bracket (resized).jpg

10 mins to replace both switches! They work perfectly in test with a ball.

Still waiting for pop bumper parts, maybe monday.

Meanwhile, my left VUK is sticking up.

Time to examine:
VUK cap (resized).jpg

Looks like the cap has been replaced and a bent nail is used to secure it.

The Gottlieb 5-40 retaining shaft is not to be found anywhere.

McMaster has a suitable 5-40 shoulder bolt so I ordered a couple. (not cheap)
shoulder bolt (resized).jpg

The plunger cap is badly mushroomed and worn down at least 3/32"
This will make the cap rest too high and hang balls on it.
It will also make the plunger poke thru too much and cause it to settle too high up.

I temporarily added a fender washer will take up the slack and fix it.
Also the return spring is incorrect, but if it works it will be ok. I ordered the correct one.

washe installed (resized).jpg

All new VUK parts ordered from Marco!

they will be here next week.

MASSIVE UPDATE ! ! !

Part one.

Before I rebuilt the pivot targets and replaced the pivot smart switches:

On a hunch I re-installed the 110v jumper and played a test game.

Multiballs were grabbed by hand and held.

All of the modes ended correctly except one, Rebellion.

In rebellion the only active targets are the pivot, pop bumpers and the left kicking target.

Manually flinging balls at the pivot target and letting go thru the pops was ok until, one of the balls drained and wouldnt make it up the outhole trough ramp easily, it took 3 tries.

Suddenly the game launched another ball?

I let the balls drain one by one, the mode ended early, flippers died and the ball ended with 2 balls still in my hand.

I put the 2 balls into the outhole and they wouldnt make it up the trough ramp.

Something is going on in the pop bumper/pivot target/left kicking target area of the game.

I already found the loose wire on the Rebellion flasher, and fixed it.

This is the first time that I could manually see something very wrong.

Pretty exciting!

MASSIVE UPDATE ! ! !

Part two:

I suspected that the pivot target smart switch was the culprit, even though the pop bumpers are crusty and tend to stick when actuated manually.

I havent rebuilt the pops yet or replaced their smart switches yet.

The only oddball part is the left pivot target smart switch (and it has a crack in it), its part of the group that failed the Rebellion mode.

Pivot smart switches are different than the other ones, they are not interchangeable.

After cleaning, lubing the pivot points, and then replacing the "smart" switches on the pivot targets I played a game.

Im still on the 110v jumper and will leave it that way. It came from the factory with it on.

On initial game start:

The game immediately plays differently. Peppier, stronger, faster responses.

Mulitball after multiball modes end properly.

Flippers dont die, the game plays flawlessly.

I made it past Ra's bracelet with a 4 ball mutiball, no errors (this is always an iffy mode on my game and rarely finishes properly).

I made it all the way to Eye of Ra, massive multiball that went on forever!

No errors, drained down to 1 ball and started a few more modes.

NO BALLS collected in the trough, ALL balls made it up the trough ramp on the first try.

Thinking this was a fluke, I played 5 more games, ZERO ERRORS.

Still not trusting the game, I left it in attract mode for 4 hours.

Played 2 fast games, ZERO ERRORS ! ! !

So, I truly believe that the game is fixed now!

This is the best that the game has performed since I bought it.

So it appears that the source of the ball count errors were due to a faulty smart switch on the left pivot target.

On the pivot targets there are a lot of pivot points.

Any metal on metal pivot points in a pinball machine should be lubed with tiny amounts of silicone oil (or sewing machine oil in the old days).

***NOTE*** I said TINY amounts of oil, it shouldnt be DRIPPING off and any excess should be wiped off. This will do a good job of "dry" lubing.

In my picture earlier, I tried to show one of the axle pins of the pivot target being externally lubed with a tiny drop of silicone oil.

This includes slingshot bearings, spinner targets or any axle pin in a game.

On some of the axle pins and press in bushings I use silicone grease.

The parts will last forever and the game will play faster.

On the left Horus guard there is a Smart switch behind the round white target face.

Its not a regular "leaf" switch that is common in pinball games.

These are NOT adjustable, do NOT need lubrication and for the most part, dont fail (unless you are just unlucky )

left horus guard (resized).jpg

Why it has failed and affected the ball count is a mystery.

Its not on the same strobe line, nor is it a part of the column or row that contains any of the trough switches or the shooter lane switch.

Its also not in any way, a part of the outlane or trough coils circuits that I can see so far.

However is does report to the CPU and I guess can WREAK HAVOC if it fails in just the right way...

YES!

You did!

But, they never go bad, even after 28 years????????? LOL !!!

I am replacing them as I go. Next are the pop bumper ones.

Gottlieb games are very robust and relatively trouble free compared to the other game manufacturers.

The main reason I created this thread was to document problems and solutions.

Comparatively little is documented about Stargate.

I will continue adding my repairs to this thread as I go through the game.

I have a fix for the sticky/weak left VUK next.

It was a tough one thats for sure.

Only 72 days to figure it out.

It might have KILLED a lesser man etc....

Now onto the rest of my examination of the game.

Im nearly through all of it.

Pops and pivots were nearly the last items to check.

Oddly, things are always found in the last place one looks...

In the procees, VERY many marginal/hacked/broken/incorrect items were found and addressed or replaced.

Plus all new electronics! Gottlieb parts are at bargain prices compared to Williams.

For a few hundred dollars I have rebuilt most of the game with all new parts.

The game plays like a dream!

Im no expert lol, but I do use a linear trouble shooting approach.

The door switch problem should be addressed by checking all the wires and diodes. Also rule out any mechanical problems.

Also look at the the column and row switches from the matrix chart. Its very possible that a wire has fallen off.

I had my upper drop targets do EXACTLY the same thing. I pulled the mech as its super easy, cleaned the switches and adjusted it and put in a new coil sleeve.

The metal slider was binding terribly and keeping the mech from working properly.

It would work but hang up if pressed at a slight angle. The edges of the slider were slightly worn and rough.

The springs arent strong enough to pull it up due to the roughness of the sliding parts.

I pulled it apart and smoothed of the rough (channel?) edges on both parts with a file. I applied a dab of silicone grease to help it.

The mech started working properly after the rebuild.

I use a little Flitz on a q-tip to clean the gold contacts of the switches followed by a little naptha to clean it off.

Left VUK coil modification.

This should give the coil a little more power instead of swapping it for a more powerful coil.

I tested the resistance of the old coil, it looks really good. The spec is 15.5 and its dead on (my meter is set to round off).
15.5 ohm coil (resized).jpg

After removing 200 turns of wire (and will add a new diode) im happy with 13.5 ohms:
13.5 ohm coil (resized).jpg

Parts came in from Marco for my pop bumpers and to rebuild the left VUK

It seems that the completely WRONG plunger and cap was installed at one point.

The old plunger is too short and has the wrong hole size for the 5-40 shaft and lock nut:
(new plunger at the top)

plungers (resized).jpg

The old cap is also WRONG. The new one has the correct size "elongated" hole in it:
(correct cap on the left)
new vuk cap (resized).jpg

The new shaft I ordered from McMaster Carr is a PERFECT fit.
(I ordered 2 in case I lost one... )
I also installed new coil mounting brackets and a new coil wrapper, as well as the correct spring:
new shaft (resized).jpg

All rebuilt:
all fixed (resized).jpg

Im hoping my coil modification will make it more powerful.
Certainly all new parts will make it work like brand new!
(installed in my game):
installed in game (resized).jpg

Pop bumpers

Removing the pop bumper coils, brackets and switches is super easy on this game.

The pop bumper bracket is held on with 3 machine screws and 2 nuts that attach it to the bumper ring assembly.

My new brackets came with replaceable coil stops! I think this is a good thing to future proof the game.

The bracket legs needed to be spread out a little to match the existing ones, but it only took a second.

A quick cleaning of the rings legs and surrounding area on the game, with Naptha, makes everything look new.

One thing about Gottlieb is that the metal and fiber yokes are built to last a lifetime, they rarely break.

Also metal spoons for the pop bumper switches.

Gottliebs are really built well.

all cleaned (resized).jpg

I bought 2 smart switches for the pop bumpers from Marco.

One of them had a pin that was never soldered for the smart connector. Its an easy fix but SERIOUSLY, no one checks anything any more.
The new switches also didnt have the lock washers on the bolts, and one of the brackets was super corroded.

A left and a right switch is listed, but really its the same switch with the bracket just flipped around.

new pop bumper switch (resized).jpg

When installing new spoons on a pop bumper its always best to put a tiny drop of silicone oil in the spoon and wipe it mostly off.

I got that tip from LTG.

Another thing about these pop bumpers is NO SWITCH ADJUSTMENT ! ! !, they are smart switches, JUST INSTALL AND GO!

All rebuilt and ready to install with new coil sleeves.

ready to install (resized).jpg

Installation is super easy and the whole job from beginning to end took 30 mins for both pop bumpers.

No more binding and they are much stronger and sensitive!

I also cannot express strongly enough how NICE it is to Molex everything.

It makes standard maintenance and inspections a BREEZE!

Amazing day!

I played the game for the firt time in 74 days just for fun. Its been a long time coming lol.

It was AWESOME!

ZERO errors, the game is fast and BRUTAL. Pop bumpers are really strong and sensitive..

Everything is really strong and FAST.

My coil mods are working better than I expected. Outhole coil works perfectly, Left VUK was strong and worked perfectly even under a full load with long 4 ball multiballs.

This is what I signed up for. A fast challenging game with tons of unique shots.

Im VERY happy

Well worth the time and parts/work invested.

Next its time to incrementlly dial in the flipper angle.

The game is close to PERFECT!

Some thoughts on left VUK problems and adjustments.

Oddly the left VUK does NOT have a schematic, exploded view or parts list in the manual.
So, its impossible to get the correct replacement parts without this important information!

My incorrect plunger as noted above was installed (I think) because the prior repair person didnt have the parts list and did the best they could.

I have included the left VUK schematic from Pinball Resource at the end of this post. The same document has been posted before on a couple other "Weak Left VUK" threads.

Its important that the VUK has a plunger that's not worn out, missing the metal cap on the end or worn and dragging coil sleeve, and has the correct spring. Too strong of a spring makes the mech fail (the williams 10-135 common spring was too strong).

If you look at the mech, you can physically bend it left or right while its bolted in the game.

If its not perfectly square to the playfield, you should bend it so that it is. A little bending is a lot. So just make very slight adjustments on this.

If the end tab of the mounting bracket (that has the rubber grommet in it) is bent outwards, you should bend it square to the bracket. If this is bent to far out, the plunger will rest too low and weaken the throw of the ball.

The idea is the get it to shoot a ball straight up the center of just very slightly to the right, so the ball can ride up without dragging or getting spit out to the left and rolling back down the horus lane.

One of the biggest complaints about this mech, is that when the game is under a high load it takes several tries to feed the ball. This can cause abnormal wear to the plunger, coil sleeve, spring and drive transistor.

If you rebuild the mech, make certain that the plunger moves exactly straight up and down. Its possible to have the plunger move at a slight angle if the coil brackets are crooked or set off center. This causes the ball to rattle in the chute.

I press the brackets firmly onto the coil and firmly and to one side while tightening the screws. Both the top and bottom brackets should align to the same side. It can be easy to be off a little and have the plunger shoot at an angle.

Replacing the coil with a stronger one is also one of the solutions. There is a bally coil (BF-27-1250 must add a diode) that is "Really close" where you want it to go as far as power, however you must add a diode to it. You can see it listed on the coil resistance chart.

https://flippers.com/coil-resistance.html

Ideally you need an "in between" sized/powered Gottlieb coil that doesn't exist.

By removing 2-3 ohms (200 or so turns) of wire, the coil is quite a bit stronger (and basically make the Bally coil without buying one). But not so strong as to bounce the ball off the top deflector, and have it roll back down onto the mech. My coil reads 13 ohms without the diode, 13.5 ohms with the diode in place.

With the modified coil, the mech is strong enough to clear 2 balls at once and not "fail" to eject balls when the game is under full load.

IMHO its really perfect now.

Here is the Left VUK schematic with the part numbers, that isnt in the manual:

VUK schematic (resized).jpg

On smart switches...

I have replaced 6 of the 9 switches.

2 special pivot mech switches (replaced)
2 pop bumper switches (replaced)
5 roll over switches (replaced 2 so far)

As you can imagine, Im a bit skittish/concerned/ gun shy, about leaving in the last 3.

I Just now ordered 4 more.

Ill install them in a few days when they come in.

(Yeah, I'm still a little shaken from broken "Smart Switches", lol )

Some info about Smart switches:

Switches:

The reliability of contact switches is reduced due to contaminates like moisture and dust which foul the contact points. Piezo film offers exceptional reliability as it is a monolithic structure, not susceptible to this and other conventional switch failure modes. One of the most challenging of all switch applications is found in pinball machines.

A pinball machine manufacturer uses a piezo film switch manufactured by MSI as a replacement for the momentary rollover type switch. The switch is constructed from a laminated piezo film on a spring steel beam, mounted as a cantilever to the end of a circuit board.

The "digital" piezo film switch features a simple MOSFET circuit that consumes no power during the normally-open state. In response to a direct contact force, the piezo film beam momentarily triggers the MOSFET. This provides a momentary "closure" for up to a 50 V maximum voltage. The output of this low profile contactless switch is well suited to logic-level switching. The unit does not exhibit the corrosion, pitting or bounce that are normally associated with contact switches.

The company has tested these switches in excess of 10 million cycles without failure.

The switch solves the nagging problem of fouled contacts in pinball machines, a significant source for machine downtime and lost revenue. The simplicity of the design makes it effective in applications.

Though it has been proposed that one could replace smart switches with regular "leaf" switches, Its not so simple.

The pulse length of a smart switch is very short and the software code that controls it is "tuned" to that signal.

Leaf switch replacements will work, but not as well as one would like. Expect switch closures only about half of the time, and lots of failed activations.

You will have to hold down the "leaf" switch for a bit longer than the "smart switch" to get it to be recognized as a switch closure by the CPU board.

This is NOT acceptable for a high speed application like a stand-up target with a fast moving ball.

Smart switches have built in circuitry to debounce the switch and simulate clean switch closures.

If a component fails on a smart switch, you get a bit of electricity pushed back into the circuit as will as a very jagged signal.

This leads to misinformation sent to the CPU and related parts.

Lastly, as I have found out, bad signal from a failed smart switch will wreak havoc in the strobe lines.

https://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Data+Sheet%7FPiezo_Solid_State_Switches%7FA1%7Fpdf%7FEnglish%7FENG_DS_Piezo_Solid_State_Switches_A1.pdf%7FCAT-PFS0012

Smart switches came today.

Now my game as all 9 smart switches replaced!

They are SUPER easy to install, and require NO adjustment.

Just make sure the metal actuator tab on the "switch" goes "over" the actuator wire on the "game". It can be easy for it to slip under the wire (ask me how I know this...).

This should buy the game another 28 years of service life!
smart roll over switches (resized).jpg

I can finally play lots of problem free games !

Now Im adjusting the flipper bat angle.

Games with worn coil stops and worn plungers on the flippers have much more travel than freshly rebuilt ones.

My flippers are freshly rebuilt so proper adjustment is critical.

Gottlieb has not provided a mark or any guidance for adjustment, other than a dimple between the flippers.

This has been covered here on pinside a couple times.

The manual shows the flippers at an extreme downwards angle.

It looks wrong, but its not too far off.

Without the droop, you cant effectively shoot the right kicking target or the lower left quartz drop target.

Too much droop and its more difficult to hit the pyramid shot or backhand the horus guard during rebellion.

Pointing the lower edge of the flipper bat inline with (or just above) the small divot between the flippers is a good starting place.

This it my current setting:

flipper angle (resized).jpg

I will have to play a few games with this setting to verify if its exactly right.

I may have to droop the flippers a tiny bit more so that the rubber is right above the anti-cheat wires.

Thank you so much for posting!

I agree, they look low. Matching the flipper angle to the wires is a popular setting, and looks better.

But for the moment Im going for how it plays vs how it looks.

Can you post a picture of your setup so that I can draw some comparisons to what others have posted, and my experiences?
The flipper angle from the pictures on IPDB that Allen Shope provided are too high and incorrect.

Flipper bat angle is a very controversial subject on pinside.

To date:

I have incrementally adjusted the flippers from the center of the lane guides downwards, about 1/16" at a time and played several games.

Researching pinside for a correct angle, its been established that some sort of droop is correct.

viperrwk, the somewhat definitive expert (awhile back) on Stargate had established a baseline similar to what I have arrived at.

A couple others have also arrived at this angle, somewhat.

Instead of just doing what others before me had done, I decided to investigate this further and do my own independent study.

If the flippers are too high (say lined up the the lane guides like many Bally games) critical shots become unavailable.
Also the flipper range of travel on Gottlieb games is so great it makes the flippers "catch all" and become too easy.

My current angle in the picture (as of this morning) above, plays very well and inlane passing/transfer is effective. However when they are up about 1/16" from where they are, the pyramid shot is easier, but the horus lane to the left is more difficult to shoot.

I may settle on a prior adjustment and raise them up a 16th". This would make them parallel the the wires.

Right now, Im looking for a good flow in the game and have every shot makeable without "tipping" the ball.

So far, I have it, plus or minus 1/16" or so.

Its just a matter of where I exactly settle on it.

Thanks so much for the picture!

I also had my flippers set that way for quite a few games

It played good and solid.

I may go back to that.

Aligning the bats to the wires is pretty standard IMHO.

Yours are just slightly above that.

Ive elected to droop down a bit further to make the horus and anubis shots more "organic"?

We'll see in a week if I keep them that way, or go to where yours are.

Aligned to the wires makes the pyramid shot a breeze, but makes the Ra's bracelet slightly more challenging, "slightly".

Really its a 1/16" change. So, its getting very close to what I would say is "close to perfect".

Either way, my game is SUPER fast and BRUTAL!

All of the work I have done has made it into a really amazing experience!

Its so fast now, I get air-balls all the time lol.

I may have to increase the playfield pitch.

Thank you for your insight!

Im not so much searching for perfection, but what is a really good happy medium.

Since Im still repairing faults and replacing coil sleeves throughout, I have a bit of time to experiment with the flipper bat alignment.

Gottlieb, I guess has left flipper adjustments to the masses to figure out, lol.

Its been a week and Ive settled on the more or less best flipper angle:

20230208_100633 (resized).jpg

My game gets about 20 plays a day.

So far no horrible errors!

However I did have a ball hang up in the left VUK subway.

The game inserted a fresh ball into play.

During play, the hung ball came free and I played with 2 balls until one of them drained.

Oddly this did not affect the ball count and the game played perfectly until the game ended.

I know that a ball hang in the left VUK is a known issue.

It doesnt happen a lot, but it can happen.

I hope to have solution for this soon.