A coil is nothing more than a spool of copper wire coated with a special high temperature insulation, and while they can go bad, it's very rare. These are also incredibly easy to check and if they ohm out properly then they are fine.

The part number actually tells you exactly what it is, an AE 25-1000 is a thousand wraps of 25 gauge magnet wire.

Now that was one DIRTY pin, but she's cleaning up nicely!

Nearly none, IIRC I had read somewhere that Stern Pinball had purchased exclusive rights to produce Star Trek themed pinball machines.

If there is anywhere I would not want incandescent bulbs its in the shields, I feel the heat from the incandescent getting trapped under the shields is one of the main reasons that these specific inserts end up with ghosting issues. For this reason, my game has LED's for the shields and nacelles as I actually prefer the traditional incandescent bulbs for this title.

I run 44's in most of my inserts and don't really worry too much since most of the inserts aren't on all the time like the shields and nacelles are, plus my machine isn't on that much, and I rarely have it on for more than an hour on any given day. Essentially it all depends on how you run your machine, if you like your having all your machines on even if they aren't being played (they were designed for this) then you may want to consider some cooling options if you plan on using incandescents

pezpunk Can you post a two pictures of your switch edge test screen, one with all the balls removed, and one with all the balls in the trough please?

pezpunk

Any luck on repairing your issue yet?

pezpunk

The first part is easy; the game is seeing balls in the trough and is trying to remove them; that is why the it keeps kicking a ball to the launcher; when in game the same is sort of true except the game also sees that there is a ball blocking switch 67 (trough up) this tells the software that the ball never made it into play, plus the program sees all your balls are in the trough...

So why is the ball trough photo transistor board not working and causing a ground short on Row 7 when 6 balls are in the trough?

This is a very odd indeed...but, all these problems point to a failure of your ball trough photo transistor board. A shorted D5 on this board would cause a ground short on Row 7 whenever it was pulled low, but this should only be when the opto is clear which would also be a closed switch 67. Normally opto switch 67 would be closed all the time, but yours isn't; your S67 doesn't close until you install a sixth ball in the trough, this makes no sense as the sixth trough ball is switch 61 and is on a different LM339 from switch 67.

In order to really see whats going on you are going to need an o'scope...maybe you have one?
I'm going to speculate that when your drop target switch wire broke, it came in contact with the solenoid voltage for a moment, this voltage would be sufficient to damage your LM339's on the trough board...the only thing I don't like is that this happening will usually take out U20 on you MPU.

I've included a couple images that show the normal operation of the LM339 on the opto board.

Unblocked Opto - Row is driven LOW while its column is active, this is why unblocked optos show as a closed switch.
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Blocked OPTO - Row is driven HIGH while its column is active.
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If you would like to send me your trough board, I would be more than happy to take a look at it for you...Just PM me.

pezpunk

Yes, I am fairly confident that replacing the board will fix your machine, I would be a little more confident if I knew for sure your column 6 drive was working even though it appears to be based on switch 68 working.

I'm more confident that your original board (assuming it's original) can be repaired, so my offer still stands to repair your board if you desire. While this repair technically would be cost prohibited over buying a new board, I'll do this repair for you as one STTNG owner to another so all you are paying for is the shipping cost.

First of all ... welcome back!

This is a tough question to answer as it's very subjective as the skill level of the people working on it varies greatly; fortunately, you have already found this thread and should you run into issues with your game you cant resolve, its likely you will find the answers here.

I would definitely be concerned with both the subway diverters and the Borg diverter based on the age of the game, this would even hold true if you found a NIB machine...if these assemblies have not been disassembled, cleaned and rebuilt, the 25+ year old grease on them will be hardened and result in mechanisms that operate poorly. Taking the time to properly rebuilding these mechanisms should allow them to operate trouble free for decades.

*** GASP ***
https://pinside.com/pinball/forum/topic/star-trek-tng-the-mother-of-all-restorations

https://pinside.com/pinball/forum/topic/sttng-left-launcher-alignment-calibration

It does look a little odd...

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Congratulations on your recent purchase, sounds like you found a gem!

Not to mention picking up a ToM in the same trip! That's a game that is VERY high up on my want list ... you have great taste in pins!

Remove all of the balls (there should be 6) then go into switch edge test, with the balls removed ALL of the optical switches should read closed.

The ball could also be getting hung up in the subway...while you have all the balls out and are in edge test, drop a ball into the subway and watch its progress, you should be able to see it pass the subway opto, and then all of the VUK optos should change sequentially until it ends up at the VUK coil.

It will shoot out (if there is a ball there) and it should come at you with a really good velocity to it.

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Zitt
I seem to recall there is a lot of positional movement to these rails and it took some time to get them positioned properly.

For those interested in the fix for this obscure problem, the trough opto photo transistor board had failed, more specifically U2 (LM339) on the photo transistor board failed, this component was causing unstable column drive pulses to the comparitor circuits as well as loading of the reference voltage.

https://pinside.com/pinball/forum/topic/sttng-owners-club/page/42#post-4174256

The board was repaired by replacing U2; due to the tiny pads, traces, and thru-holes, I have to say the skill required to replace this part is fairly high.

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CONGRATULATION! This is an outstanding pin to add to any collection and a great way to start a new collection.

Drill a hole in it (be careful to only cut through the fist part of the bottom to minimize damage to the wires,
Fix the wiring and tuck it out of the way.
Cut the second half of the hole
Use hot glue to secure it to the flasher.

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The gearbox is supposed to be sealed ... no liquid or or out.

I just like posting pictures...

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I still dont know whats wrong with the drop target...Does it not drop, or does it not raise? The drop target has two separate coils and two separate drivers for these coils but you haven't provided enough information about the problem for anyone to respond to. Please provide more detailed information about the issue you are experiencing and you will surely get better responses.

Attached it the wiring information for connector J114 you were requesting, hopefully this will aid you in solving this issue.

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That'll do it every time

Glad you got it fixed; this game was made to be played!

11.56 is very low for the unregulated 12V.

Warning: Replacing PBD capacitors is not a simple repair; many folks that have attempted this ended up damaging their boards by braking traces and pulling out thru-holes.

I cringe everytime I see someone say this but wish you the best of luck with this repair.

J116, J117, and J118 on the power board are all wired the same, this is where your +12VU leaves the PDB...one of these is your playfield 12V that controls everything that isn't working. Do a good inspection on these, if they look fine, try swapping them around. If none of that helps you are going to have to start measuring your 12V under the playfield (Grey-Yellow) to see where it gets lost.

if the color DMD works then your 12VU is fine as the Color DMD uses 12VU exclusively in operation.

Don't get me started on the reset fix ... I've made it clear where I stand on this ...

The best place for you to start is by measuring the power supply voltages on the PDB, post these numbers here and we can go from there.

I was actually expecting test point readings, but I can work with this; your 12VR is a little low at J114-1 and probably a little lower at the MPU, but I don't think this is problematic...yet.

Your 5V is a tiny bit low at J114 but likely lower at the MPU since there are a total of 4 connection points between the PDB and the MPU...a few tenths make a difference here; ideally, you should have around 5.2V at the 5VR test point TP2

At 15.8V your 12VU is fine, and you should have plenty of power to drive your DMD and other features. This voltage is actually a little higer than it should be and I suspect its due to it not being loaded by your playfield boards. I suggest that you start chasing this voltage down under the playfield as there is probaly a break in the circuit. With your playfield raised, the voltage will feed to the bottom right parts first and make its way across the playfield in an inverted U pattern. One of the last points to receive this power is the 16 OPTO board, this means a break in this voltage anywhere along the way is going to cause some serious issues.

This is possible, but I don't see anywhere where it was measured, the only place you can measure this voltage is at TP8, and there is no voltage readings recorded for this test point.

I'm going to just assume these are reversed as you just cant have 12V on the 5V line, and 5V on the 12V line on this connector

Sorry, I was confusing your problem with another guys that has no working cannons and other 12V related issues...

Like mavantix mentioned, this is likely a problem with your 18V lamp matrix, please measure TP8 and report back with your readings.

Below is a diagram to aid you in locating your test points:

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If anything, I suspect your 5V regulator on the MPU ... and your reset fix. please measure the voltage across the C31 on the MPU, if this voltage is lower that 4.9, remove the reset fix and remeasure this voltage. Please respond back with all these measurements.

I think I got off track here a little bit as your were asking for help for strobing GI's. For your 5V section you are loosing .2V between the MPU and PDB, this is going to be caused by headers/connectors and is one of the primary caused of your original reset issues. The 5V is also starting off low, replacing the 5V regulator would likely correct this, but for now your reset fix is working, just keep this at the back of your mind if you experience additional issues with resets.

For your

Is it just GI's that flicker, or is it all lamps in the game? If its just the GI's then I would suspect an issue with the dimming circuit or control data. There is a couple of easy things you can try...

Flip over the ribbon cable between the MPU and PDB, this will make change the conductors used for communications.
Go into game settings and disable the GI dimming feature, if the problem persists, the issue is likely on the PDB itself.
Pull the MPU, place on a hard flat surface and press in on the ASIC chip to ensure its seated well.

General dimming "theory of operation"... from PinWIKI http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#GI_Lamps_Not_Dimming

The driver board generates the ZC signal with the BR2, D3/D38 and U6 circuitry (different resistors).
The ZC signal is connected to the ASIC (across the driver board, the ribbon, and then across the MPU).
The ASIC uses the ZC signal to determine when to send the /TRIAC signal to U1 pin 11 (an 74LS374 buffer IC) as it simultaneously presents GI string enable data on the data bus.
U1 latches GI string enable data from the MPU's data bus.
The output of U1 forms signals T0 thru T4, which enable the TRIAC circuitry.

I can do trace and thruhole repair and may be interested in purchasing this board; if you are interested in selling the board please PM me with pictures of the damaged areas and I would be willing make an offer on the damaged one based on how much time I anticipate having to put into it to make the proper repairs.

NOTE: The term "proper repairs" is very subjective; IMO proper repairs of thru holes mean installing solid copper eyelets of the same inside diameter and pad size as the original (see 3 repaired pads in pic below ). I may have a mild case of OCD...

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Once tinned before installing parts, these eyelets will look exactly like the original pads, but you cannot get a soldering iron hot enough to damage them.

The technique is relatively straight forward, first you clean the area the best you can. This board didn't need new traces so it was a fairly straight forward process. The most important part is having the right size eyelets, to match the circuit board, as these must be the right length and diameter.

Once you have your eyelet selected, you need the matching ball mill to drill out the hole to the same size as the outside diameter of the eyelet, DO NOT use a regular drill bit for this as it can damage the traces.

After the new holes are done the eyelets should fit right in, yet be snug enough to not fall out. For these I used a hand setting tool and small hammer to set them and then tap them flat, since these are copper they work really easy and flatten right out without a lot of force.

Circuit Medic carries a lot of the stuff to do this kind of work and I believe have guides available on line. http://www.circuitmedic.com/products/kits.shtml

I've been doing work like this for a long time and have access to kits that haven't been produced in a very long time. The eyelet kit used in this specific repair is shown here:

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Unfortunately the price of these items has really escalated as the demand has decreased. The fact is we currently live in a "throw away" society and its more cost effective to buy a new board than to hire a technician to repair the original board; this killed off the repair sector and escalated the cost of repair materials which are much harder to find these days.

The kit pictured is in a really nice felt lined metal box and was manufactured in the late 70's or early 80's; this was one of the manufacturers sample kits they they would provide to the larger repair facilities. I consider myself very fortunate to have acquired this kit.

This is a mechanical issues, the ball only goes where its directed to go, it takes the electrical action of a coil to direct the ball to anywhere other than the upper left VUK...in the absence of this electrical energy, only a mechanical force can keep the diverters closed and direct the ball to the right gun.

Only a failing opto in the right gun can cause the game to go into ball search at this point. No matter how clean the game is, it looks like you have multiple issues happening here.

STTNG Guru

First off, WELCOME TO THE CLUB!!! You now have, what I consider to be, the best pinball ever made.

The only "real" issue I see here is that you have a bad trough opto, and in this game its a big problem. More than likely you either have a broken load resistor on your transmitter board, or a failed IR LED, these are very easy to fix. The opto board is subject to a lot of vibration...especially if its a first generation board without the anti-shock bushings.

You can see them under the mounting screws. They are black runner grommets with metal sleeve in them, the sleeve allows you to securely tighten the board in place while still allowing the board some movement to absorb the shocks.

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If BR5 was bad it should blow the immediately and all the time; since this is the only fuse for the entire 12VU circuit, you may have other issues going on that may not be tied to the PDB

That doesn't sound right; figure 1 and 2 should measure the same.

This is the BR for your flashers, it may not need to be 35A to operate and it could be that the only reason a 35A was used as it would have been cheaper to manufacture these boards using only one type of bridge rectifier vs sourcing multiple parts. Its up to you if you want to replace it, I probably would because it would annoy me knowing it was different.

I like to recommend the following hardening procedure to anyone that has experiences issues in this area.

1. Locate the +50V DC tieback wire which is a THIN violet-green wire (normally soldered to the drop down target coil)
2. Cut this wire from the drop down target.
3. Carefully extract this wire from the playfield solonoid harness back to the cable management ring below the aux driver board... NOTE: this can be a PITA to do, and you may need to cut and replace multiple wire ties along the way, but keep telling yourself that it will be worth it in the end.
4. Once removed from the harness you will have a lot of extra wire (a good thing) you need to have enough wire to reach J108-1 on the power driver board. J108-1 is an ideal location as its unused in STTNG, and pin 1 is fused by the same fuse that powers the subway coils so if you blow a fuse and loose power at this pin, you also lost power to the coils/drive transistor it protects.
5. Using your favorite type connector (I use IDC) land the wire at J108-1, be sure to leave yourself a few inches of wire for future repairs.
6. Play your machine!

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Failure of drive transistor causing the coil to lock on is the primary cause, this failure often occurs from a missing tieback voltage.
Another possible cause is a bad ribbon cable between the MPU and aux driver board, verify that this cable is connected properly on both ends.

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The best way to troubleshoot opto problems is to remove all the balls and look at your switch edge test; any opto that is not closed will require attention. This simple test will immediately identify the majority of opto issues.

How did you test these? If you tested these by looking at them through a camera, they may be glowing, yet lack the luminescent intensity required to activate the photo-transistor.

While I feel it's not common to have so many simultaneous failures, you have to keep in mind is that these IR LED have a limited lifespan; while it's a long lifespan that's rated in thousands of hours, on a game that's over 25 years old it would not be uncommon for this time to be reached. The most cost effective way to repair these optos is to bulk buy the individual IR LEDs. You can pick up 100 IR LED's from Mouser for $25.50, which in the world of pinball is practically free. https://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/QED123?qs=sGAEpiMZZMtdAabcSkQOlzjLIThujcXr You can also buy the exact same item for as low as $1 each from Marco if you prefer http://www.marcospecialties.com/pinball-parts/5671-12731-00

I didn't think it was too difficult; there is just a lot of stuff, so take a lot of pictures. Probably the toughest part was getting all the wireforms to line up properly

Welcome aboard, Captain!

FL-17636 was an experimental coil that was installed in early runs of STTNG, and the original manuals will show this is the correct coil. It's my understanding that later runs of this machine had FL-11629 coils installed and this is supported by documentation included in the Williams Green parts catalog dated July 1996. (see image)

FWIW: I have the original FL-17636 installed in my machine and have no issues making this shot; the most important thing here is that the flipper needs to be right inline with the ball guide, any error in this alignment will result in a weaker shot. The one thing I do notice is that the FL-17636 has a much weaker secondary, so fast balls have an easier time moving the flipper, the EOS (if adjusted and working) will then apply full power to the coil knocking the ball away.

FL11629 (Blue Coil Wrapper) - power 4 ohms; hold 132 ohms
FL17636 (Blue Coil Wrapper) - power 4.4 ohms; hold 373 ohms
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One of my favorite STTNG pictures:
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1) run a display test and let it complete all the way thru to see if there are any RAM or aging errors

2) replace the long ribbon cables

WTB your original Power Driver ... please PM me.

Check your alignment of the wireform at the exit side...if its not tossing balls right down the middle of the lane, the ball can loose a lot of momentum.

Coils generally either work or they don't; this particular coil is an AE 23-800 and should have a coil resistance of 4.2 ohms. If it reads close to 4.2, then there is nothing wrong with it.

The machine I current have was having a similar problem as yours, what I found during the restoration is that someone tried to fix this by removing nearly 1/3 of the coil wingdings in order to make the coil stronger ... I'm not going to say what I said when I found this during the games disassembly...

The true problem my machine had, is that someone in the past installed the wrong coil stop in the game (the correct one https://www.marcospecialties.com/pinball-parts/A-16886 is an odd size that was rarely used). This coil stop gave the catapult more throw which caused the ball to be thrown onto the rail rather than down the rail which killed a significant amount of the balls momentum; you can actually see the wear at the end of the rail from the balls being repeatedly hammered into the rail.

I would start by replacing the coil sleeve (https://www.marcospecialties.com/pinball-parts/03-7066) and the coil stop. After my restoration and alignments, the ball hit the drop target so fast that it would bounce all the way back into the right orbit...this settled down once the wax was worn off and the game got a little dirtier, the ball then started finding their way into the top lanes as they should.

Good luck!

This always seems to happen to me as well...within a day of ordering something from Marco I found out there was something I need that I didn't order; like you, I generally add additional things so I don't spend more in shipping than merchandise

Make sure your mark switch is functioning properly in cannon test.

it is, it should normally register as a closed switch (unblocked)

Strange, this part should never break. If the shaft is broken, you can probably just epoxy it back together and it should last forever; if not, at least they are cheap. https://www.marcospecialties.com/pinball-parts/03-8620

This failure is caused by the cannon optos indicating a ball is in the cannon and is usually caused by a failure of the the IR LED or cannon wiring.

This will help you:
https://pinside.com/pinball/forum/topic/sttng-left-launcher-alignment-calibration#post-4126168

oooh....the small one is a PITA to replace. This is the one that connects directly to gearbox shaft and is held in place with a retention pin...the pin is very difficult to remove, I broke 2 punches trying to remove one

Power on yes, play...NO.

run a full diagnostic on the display.

The Hallmark ship is only scary because there is so much unknown about the mod, but once you know whats going on its fairly simple.

Myth: There is a circuit board in the ship that's needed for it to operate.
Fact: All the circuit board does is convert 120V AC to DC for the two zener diodes to "regulate" the voltage to around 6.5 volts. Since we already have a 6 volt GI circuit we dont need any of this for it to work as the ship contains 4 incandescent bulbs and they could care less if the voltage is AC or DC for them to glow, as long as its around 6V.

Well heck, I guess that's all there is to it. Of course I've been known to back up what I say with pictures so I won't disappoint.

I was once in the dark with this board as well so I cracked open a Romulan Ship to see what I was dealing with...that's when I found the spider! Okay, not a real spider but this little board with its 8 yellow wires just looks like a spider.

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Each one of the Zeners in the picture above control one side of the lights and are wired in series in order to reduce the overall current draw.

I would like to strongly discourage taking one apart like this as it is absolutely the hardest way to mod this AND you will chip paint around the warp nacelles which light will shine through and make it look bad.

The best way to do this is to just pull out your drill with a 1-1/4"/32mm hole saw and cut all the way through the bottom layer of plastic, then STOP! The reason you stop when you are through is to minimize damage to the wires, if you go too deep you will start damaging insulation, making more work for yourself. If you drill this perfectly, ALL of the wires will still be connected to the board and you can just cut them off, or desolder them if you prefer.
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After the board is out of the way, tuck all of the wires inside the ship then get your drill back out and cut through the top layer of plastic; since you already have 2 guide holes this is a simple cut, you only have to worry about going too deep and scratching the underside of the top portion of the ship in a place no one can see.

Just take all of the wires, solder them into a single 4 lamp series circuit and call it done. I used heat shrink over every connection and installed a 2 pin molex connector in place of the original tree lighting socket and called it done!
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All thats left is to wire it to any GI socket you see fit, if you made it this far no explanation is necessary. I hot glued mine down to the flasher cover, but realistically the ship never moved while I was game testing it, so its up to you what you want to do here. I cannot fall off as there is no room for it clear the flasher with the glass on, but it may fall if you raise the playfield and don't have it glued down.
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Engage!
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EDIT: FURTHER INVESTIGATION INTO HOW I WIRED THIS REVEALED THAT I ACTUALLY ONLY WIRED THE 2 LIGHS ON EACH SIDE IN SERIES WITH EACH OTHER AND WIRED THE 2 PAIRS IN PARALLEL. THIS IS HOW THE ORIGINAL BOARD WIRING WOULD HAVE BEEN AND RESULTS IN THE SHIPS LIGHTING HAVING THE PROPER BRIGHTNESS.

IT IS MUCH MORE DIFFICULT TO WIRE THIS WAY AS EACH OF THE GREEN POWER WIRES WILL HAVE 3 WIRES SOLDERED TOGETHER.

I have another Hallmark ship I can work on and post new pictures of the wiring changes needed to produce optimal lighting.

Just loosen the 4 phillips screws holding the canon to the shaft, turn it to line up with the wire-form, tighten it back down, and start playing...you earned it!

These are slotted to give you lots of wiggle room...

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Probably not, I took around 1500 pictures when I did my full restoration; I have pictures of every sub assembly as they were disassembled and rebuilt.

LOOKS GREAT!

I would have been VERY disappointed with that, no way it would have went in my machine either.

I dont know what gain this mod has since you can easily install AA sized lithium batteries in the battery holder

LX7

I guess this comes down to a personal decision on which is better. The following information is provided in order to provide everyone reading this thread with more information on this so they can make an informed decision on their own.

Cheaper, maybe; you would have to calculate the cost of the mod in addition to replacing the battery every 3 years instead of every 10 years. Current pricing for a pack of four AA Energizer Ultimate Lithium batteries is $6 USD; of course if you buy these in higher quantities for all your machines, remotes, etc, they are much cheaper.

Easier to purchase? I disagree. AA sized Energizer lithium batteries are available everywhere you can buy batteries, and your ease of purchase is as simple as walking into Walmart with cash, check, or credit card, or just ordering them off amazon . Last time I checked, the coin cell mod cannot be purchased nearly as easily, personally I don't even know where to get one as I never considered getting one.

Storage space for spares? Are you serious? Why would you store spare batteries for something that only needs to be replaced once a decade? besides, I automatically assume that if you own a pinball machine, you have adequate space to store a single pack of 4 AA batteries even though you shouldn't?

10 min to complete is actually much longer than it takes to install 3 AA batteries in the existing battery holder...plus you can do it with the machine power on so that you don't loose any high scores, game settings or audits. perhaps I'm not familiar enough with the mod, but the one I saw required pulling the battery holder and replacing it a new coin cell holder, this type mod cannot be performed by everyone.

You're on the right track, I would replace the capacitor before performing any further troubleshooting. Should be 25V 100uf aluminum electrolytic

I believe the game tests only one cannon to check the validity of the column 9 pulse on startup, if more than one cannon is being tested, the game is checking for cannon switch operation prior to flagging a switch error for failure to change states in X games.

Possibly, but your issue is going to be a VUK opto or subway issue. Fix this problem, play a few games to start Battle Simulation, then power cycle the game and see if it continues to test both cannons

Neither one, ONLY use the metal ones!

They do, but you really shouldn't worry about that as once installed they are never coming off and you will have no cabinet damage from the legs. This is the best thing you can purchase to keep your obviously pristine cabinet from being damaged. Don't use similar ones that are made of plastic (like stern uses on LE's) as I can confirm that they will not provide the same protection.

Welcome aboard Captain!

Original silk screen was not applied to wood, the original silkscreen was still applied to a vinyl type material bonded to the plywood; while better than decals, it can still wrinkle.

LA-7 is fine ... LX7 is the international version of the same ROM.

This is what it will look like with metal protectors (some parts on this machine are missing)

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Assuming you aren't waiting too long which speeds up the selection rate, closure of the upper right and upper left flipper optos is what allows you to manually change the selection, you may want to clean them and see if the problem goes away.

For clarification, ALL WPC89 games have four flipper switches, most of which have programmed functions even if the game only has two flippers.

Welcome aboard Captain!

This is good advice, the diverted is normally open to the Borg ship; it is pulled closed by delta ramp entry opto when Borg Lock is not lit.

Awesome find! Just wait until you find out what all needs to be removed to replace it

you already have some damage A Mantis is better at preventing the damage to start with but a cliffy will cover up existing dame and provide protection.

Image below is a mantis protector installed on a new board with 0 plays. NOTE: The Mantis in the photo below sits slightly lower the top of the playfield which could result in minor damage to the clearcoat; routing out a tiny portion of the mounting location on the bottom side of the board to bring the Mantis flush with the topside could guarantee that damage would not occur.

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Welcome aboard Captain!

They should flash in T8 All Lamps, or in individual lamp test T8 - 56
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This is a classic symptom of a cannon opto transmitter failure, essentially the game is seeing a closure of the cannon switch telling it there is a ball in the cannon; it could be caused by low 12v to the opto board under the playfield, bad connection to the opto transmitter in the cannon or at the 16 opto board, a bad filter capacitor on the 16 opto board or even a failing LM339 on the 16 opto board.

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I have on for sale ... its a fully populated pristine playfield (better than new condition) and 100% operational. I will ship it in a 3/4" plywood cabinet with a glass inspection top layer for only $6000.

Welcome aboard Captain and CONGRATULATIONS! This remains one of my all-time favorite games.

Its in your best interest to become familiar with the information contained here http://pinwiki.com/wiki/index.php?title=Williams_WPC

For your current issue, look specifically in this section http://pinwiki.com/wiki/index.php?title=Williams_WPC#Display_problems

You can also try swapping in parts from your TZ to help isolate the issue.

I looked at your playfield pictures from this post some time ago and something was just off about it and I finally figured it out! The playfield you are rebuilding has what appears to be a Dec 14 manufacturing date and is likely why I didn't recognize the color registration marks on it. What really threw me off was the playfield in your picture has a machine specific barcode label (SN 336042) for the specific game it came from ... unless I'm still missing something, I'm assuming this doesn't match your machine at all.

Images Original playfield from machine S/N 432591 and matching part labels:
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Nice, I wonder if they had multiple board manufacturers for this build.

This doesn't sound right, What is your voltage at TP1?

You can disconnect J116, J117, and J118 one at a time to try and find out which one is pulling excessive current. You will want to keep your coin door open for this as all of your optos will loose power during these tests and cause the game to freak out.

I wouldn't worry too much, but I also wouldn't spend too much time trying to fix a 25+ year old plasma display. A color DMD is one of the best upgrades you can do for STTNG, but if you are on a tight budget you may want to consider a cheap monochrome LED display. Either way you go, the driver and display will generate less heat and use less power, its a win-win.

There are no optos associated with this, and since this switch is not part of the cannon wiring harness AND you are sure that the switch is good. Then the solution is simple!

1) The 8 driver PCB is NOT sending the column 9 pulse to the left gun home switch (J5-1 (VIO-WHT) to SW97)
2) The 8 driver PCB is NOT passing the closed switch data (SW97) to the CPU (J5-1 (VIO-WHT) to J209-8 (WHT-VIO))

EDIT:
3) The cam is not actually closing the switch when the gun rotates to home (switch would function in edge test when manually pressed, but fail to operate on its own) Mechanical adjustment of the home bracket and/or switch positioning on the bracket.

Correct. When you say the cannon cant find home I assume you are getting an error seeing a X "cannon cant find home" error, or you are seeing a home switch error in canon test.

A failed cannon opto will cycle the cannon and fire the cannon coil repeatedly in an attempt to remove the ball from the cannon.