Tuesday, June 30, 2015

Corvette: how to tear down the playfield (aka removing the LT5 engine unit)

In the spirit of my post about how to tear down the Baywatch playfield, I wanted to present a concise summary of how to get the playfield apart on a Corvette, with the end goal of getting the LT5 engine out.
I have a lot of pictures in my prior, less-focused post.

Step 1:  remove the right racetrack.  You can follow the instructions as per the "Unit Disassembly For Repair #16-9887" PDF available on the IPDB page.  This race track comes off with just a few screws and connectors being removed.

Step 2: remove the left wireforms.  We are kind of following along the instructions for taking out the LT5, at the very least we take off the plastic engine piece.  There are a few screws around the Pit's VUK wireframe assembly, and the left wireform it is attached to connectors to the left slingshot assembly.  That all comes apart and the wireframe should be easy to remove.

Step 3: remove the right wireforms.  In a similar fashion, considering it is attached to the right slingshot plastic, we can fairly easily take the connected 2 right wireforms.  This will involve some wiggling to get them removed from the ramp, but you should be able to finesse it.

Step 4: removing the back "race ramp" and the "route 66" ramp.  This is all one giant plastic piece.  First up, there is a diverter for route 66.  This is held in place via a single pin beneath the playfield.  The race ramp has a few screws connecting it at the back.  The route 66 portion has a few connectors that need to be remove, and a few screws, including the two small screws at the ramp flap.  One of the connectors feed beneath the Skid Pad ramp, so you'll have to remove the 3 screws for the Skid Pad as well (might be a bit of contortion required) in order to feed that disconnected connector through.  Then the large ramp assembly should come out. 
You can leave the Skid Pad ramp a bit loose as it will be required to move again when feeding that one connector back through the playfield.

Step 5: TAKE OUT THE LT5!   We can get back to the provided documentation for taking out the LT5.  One thing they neglect to mention is that there is a gate controlled by a solenoid that is mounted at the back of the machine.  You'll need to take out the spring that attaches the solenoid to the gate, which I found a touch annoying.
As per the instructions provided by Williams, lots of connectors beneath the playfield, 2 bolts, you should be able to lift the whole thing out.

Step 6: Remove the kickback exhaust assembly.  Not often needed, but while we have those left wireforms
off we can easily take apart the exhaust assembly, if needed.  Meh, why not?  Just a few screws.  Seems kind of an anticlimax after you have that monster LT5 unit out though.


Corvette shop job has begun!

It has begun! The ginormous Corvette shop job has started, only to be interrupted for a week of vacation.
Williams released bonus service docs specifically for removing and repairing the 2 big toys, the racetrack and the LT5 engine.
In tearing down Corvette the first thing is of course the race track on the right, and this comes apart readily for relatively easy maintenance.
The racetrack has one main connector at front and some easily accessible ones at the back, and minimal screws.  Very easy to remove.

But for me the big thing is getting the LT5 engine out. I had spent about 200 on a loaded replacement ramp and was eager to get it in.

The old ramp was busted at the entrance left side, although mostly hidden by a makeshift piece of metal, and busted at the upper right. The upper right break meant that there wasn't anything to secure the top gate to, so a prior owner had connected it to the pit stop upkicker wire frame with a cable. It was a bit messy but mostly worked.

So I started the steps for taking out the Lt5.  If you check the IPDB page, there is a PDF there called "Unit Disassembly For Repair #16-9887", and it is a cool document because it has the step-by-step instructions for taking out the racetrack an the LT5.  The instructions for the racetrack worked out great for me, so I thought "OK, let's get to these LT5 instructions!"

As it turns out, things weren't so straightforward for the LT5.

Here is the engine unit from below.  A number of connectors to be removed, and at the top left you can see the dedicated control board.  The two bolts at the top secure the whole unit to the playfield.

With the engine plastic removed you can see the large unit.  To the left you can see how it goes behind the back ramp.  On the right you can see how the gate had been somewhat attached the VUK wireframe for stability.

One step was to remove the pit upkicker wire form, but that involved removing it from the left wireform, which is connected by an inverted bolt that is nearly impossible to get to, so best take out the upkicker wireform and the attached left wireform.

Here is that annoying bolt, seen with the wireform flipped over.  So annoying to remove these as installed, so I just take out both wireform parts and leave the bolt connected.

both the left and right ramps connect to the slings, so be ready for the whole thing to need to come apart.
One other thing the manual neglects is that you have to detach this spring that connects behind the back of the playfield.  This controls the back gate on the LT5.

One instruction was then to take 2 screws off the ramp that runs along the back.  You know what?  That is nowhere close to enough.  You CANNOT get out the LT5 unit with the ramp along the back!
But then on close inspection, you notice that the back ramp is a single piece of plastic with the right ramp!  It's a huge thing.
BUT, you cannot get that plastic going anywhere unless you take off the right wireforms, which, LUCKILY, come apart rather easily after you take down a few screws and the right sling parts.
Once loosed, both wireform parts can be wiggled out of position with a little elbow grease.

That leaves us in this position:
both wireforms have been removed

Next up, to get the big plastic away you have to remove the diverter (in upper right) by detaching the pin underneath the playfield.  There are a few connectors to also remove.  One problem is one connector is fed beneath that far-right Skid Pad ramp, so you need to remove three screws to loosen that ramp to get the connector out and the major plastic assembly out.

With the major plastic ramps gone, we can FINALLY remove the LT5!  (There is no reason really to remove the Skid Pad from the playfield)

LT5 unit remove, with the ramp detached from the mechanism

closer look at the mechanism, which balances and aligns via 4 solenoids and a control board, plus optos.

New ramp on the right with many of the pieces already transferred over.  The left's entrance is broken, shielded by the makeshift piece of metal. Also that upper right post plastic is smashed off the old one.

While we're here, best to take a moment to install a Cliffy on the pit hole:

wear all around the hole

most of the damage is hidden by the cliffy

What else?
One minor thing to work on was taking apart the exhaust pipe kickback, cleaning it, and adding LEDs.
Oh yeah, I was replacing all lights with LEDs as I went and here is to hoping I NEVER have to do this again!  ;)
This part is really easy to access with the left wireform off.

And one last thing I noticed, there was a tragic accident in applying the Skid Pad decals, I assume from the factory.
Alas, trying to take this off and redo it is not a job for me.  This machine needs new decals on the side of the cabinet, perhaps a new decal at the back, and someone who does that can take care of this.  :)

can you see the issue?


So that is how it sits!

I found that the the left up-kicker wireform had a single weld that had come loose.  That has now been sent away for re-welding.
As well there are new plastic tubes for the engine, but some of the grommets are missing, so a makeshift solution for that will be required as well:
only the left hole has a the black grommet here...

Thursday, June 11, 2015

Raven: investigating board issues, starting ground mods

I brought in some help tonight and we looked in to the persistent issues.
As I suspected, the driver board had ISSUES.

Look around you.  Look around you.  Can you see it?

Oh, here it is:
Pop quiz, pinball hotshot:  are transistors supposed to crumble?




Answer:  no.

Here are some quick notes about the board:
Q22 is L21, the spinner light, which I think is accidentally always ON.
Q35 is L24, the 1X light, and via manual ground testing works fine.
Q46 is L45, the right-bank center lamp.  also operates fine via a ground test (and that is ground transistor manually to verify the device driven by it is A-ok)
Q48 is L47, right ramp exit
Q52 is L51, left ramp exit

Q35 is listed as MPS-A13, but the other above 4 are MPS-U45 (which also reads 8532 on the component.)

Oh but what about the lower right solenoid, you might say?
(yes, you might say this.  Technically true)
Q63 is an MPS-U45 pre-driver for the larger 2N3055 transistor Q64.  We grounded Q64 and the solenoid fired just fine.
But the funny thing?  Testing later, the lower right sniper solenoid fired just fine!  Was it a bad transistor, or just some cracked solder that shifted when we touched it in our test?
Best to reflow that once we have the board out at a later date.

This is all useful stuff for prepping a shopping list.

In the meantime?  Work has been started on the ground mods.
alas, there has to be a better way.  Alas oh Yorick...

Also did work on the upper right drop:  It wasn't registering at all, but now it is.
As well I got the plug changed.  The old one had the ground plug RIPPED OFF, so now we have a proper 3 prong plug attached to the game.

I do need to get on the parts soon, because the game is currently unplayable.  I took a mild emery board to the EOS switch on the right flipper and the contacts readily fell apart, so that flipper is currently useless.

you could also use a new spring, and to not have your diode by the coil stop.  Just saying.

Introducing... Eight Ball Deluxe!

Only once did I have a proper taste of the SS machines...  and Beat The Clock just wasn't for me.
But here we are with a wonderful example of the iconic classic, the machine that would set a high water mark against much of the 1980s...


This game is oh so much fun.  A great ruleset, especially consider how it is set up.
For example, get A and B rollovers, then C or D to drop 2 targets.
Collect the 8 ball, then you can spell deluxe to reload the drops during the same ball.

This is a tournament play classic:  The drop target resets fully, then individual drops return the drop bank to the position you left off last time.

And you better damn hope you clear a rack on your first ball or else you're playing mad catchup.

This game was graciously lent to me by a friend who just happened to have doubles.  A good problem to have, and a generous game to offer!

Very little wrong with it, but of course I can always fine-tooth comb some issues:
- the "game over" lights on the backglass don't light, transistor issue
- drop-bank ball #13 doesn't light, also transistor I think
- backglass lights should be swapped for warm #555 bulbs so as not to bake the (NEAR MINT) backglass unneccesarily.
 - inlane clear plastics are makeshift and warped, and should be replaced so the ball always returns smoothly to the flipper (shades of my Corvette issue!)
- right slingshot would fire and stick out
- plunger spring is a bit broke and should be replaced

Here are those inlane plastics.  I think they have been replaced once before with something, but I should try and get some cleaner and smoother plexiglass or lexan forms in there, tracing from a better copy and then adjusting...

ball bump!

bumpity bump on the little lip

I assure you that is not supposed to stick out.  Turns out it just needed a new coil sleeve and general cleaning.

This will have a lot more satisfying punch with a new spring

Oh, and you know what the only downside to this pin is?  The head is massive.
So that's a normal sized head, with an extra large trim at the front.

Yep, that means this great pin is relegated to the exiled "4th position" in my lineup for good due to the size.
Don't worry EBD, you know I still love you.