Gottlieb Incredible Hulk Pinball - 1979

Friday July 6, 2007

This HULK machine has been sitting here for a couple of months. I've know a guy who's been wanting to, graciously, take this off my hands - 'as is' - due to it's collectibility. It's about time to get it working. As I've finally got the EM shooters out of here, and hopefully to good homes, and got the plumbing re-piped it's time to get back to fixing some pins.

Gottlieb Incredible Hulk Pinball - Project Photos

I bought this non working just like everything else. The cabinet, playfield, and backglass look good. Cosmetically I'll give this a 9 due to trivial defects, scuffs, some extremely minor backglass pinholes, etc. The legs had a little bit of rust through the chrome. A little rubbing compound and some patience takes this right out - $2 a can.

Rusted Pinball Legs - Rubbing Compound

Here's the backglass from behind - looks good! See the small pinhole marks - otherwise solid.

Hulk Pinball Backglass

The playfield is also nice with signs of never being cleaned or waxed but not getting very much play.

Hulk Playfield

However, it wouldn't be in my hands unless it were somehow screwed up.

Admittedly I've only worked on a few of this vintage of Gottlieb. While in the arcades everyone was running William's machines so I didn't get much opportunity. We had one Joker Poker which lasted about 3 weeks but I did remember having issues with the slam tilt.

There is a TON of corrosion on the CPU board and surrounding areas. Most of the molex connectors were shot and fell apart in my hand. I was amazed at how much sanding was required to get the edges back to copper.

Corroded Gottlieb System 1

Look closely at this edge connector and see several pins broken and many compressed so far they'd never touch the cpu edge copper. There is no way these could actually have worked being that compressed and corroded. This connector, and a few others, will require a full replacement of the pins which will take many hours of work.

Damaged Molex Connectors

I shunted the reset circuit by shorting a capacitor on the CPU board.  This allowed me to determine if the CPU was running. It was running!

When I power the machine up and wait five seconds the displays light and alternate every 5-6 seconds. None of the playfield lamps or switches work. I can't coin up or start a game. This is probably due to the numerous bad edge connector pins and, perhaps, additional board problems I'll get to the cpu once the connectors are done. I'll have to get back to this project when parts arrive.

As some critical parts are not available / hard to find if I run into a board problem I can't easily fix I'll order one of those Ni-Wumpf boards or that other one from France with all the drivers.

For a detailed look into a system one repair look at Marvin's site

July 15, 2007

Nasty, nasty.... After replacing about 100 corroded pins I decided to power up the game and see if it made any difference. Of course it didn't and now I've got a missing 5 volts. I decided to look at the power supply. It seems it was going into overvoltage and shutting down. I cleaned the adjustment pots and set the voltages. So far so good but unfortunately the power was still intermittent. It seems there are some loose connectors on the supply.

moving the power transistor

I HATE this kind of construction where the power transistors are mounted in such a way that you can't test the circuit from the trace side without disassembling it. The picture above shows the power transistor relocated on the same heatsink. I drilled holes using the brown insulator as a template. The case/collector of the 2n3055 transistor can't contact the metal and must be mounted using an insulator. You can use the one currently on the board. Use a heavy gauge wire (14/16 awg). The transistor is mounted near the edge so the power supply pcb can mount back where it was originally - notice the transistor hangs just a bit over the edge. Another option is to purchase a new TO3 heat sink and remotely mount it. This has the added advantage of removing heat from the pcb.

In any case I can now test and operate the circuit while having access to both sides of the pcb. It turns out there were bad connection on the pins and a bad capacitor. I'll replace all the electrolytic capacitors later.

The cpu pcb itself was in bad shape from battery acid. I went ahead and changed ic Z8 and Z28 which were badly corroded. I didn't even check if they worked on not. One trace had been eaten - I assumed this was my coin-up issue and didn't bother confirming with the paperwork.

As a side note I usually don't have parts on hand but I do have a pickle jar full of TTL 7400 series chips and usually get lucky. The Z28 is a 7405 - I had a 7406 ( 30v version) which subs just fine.

Corroded CPU

I also replaced about 20 6.8k resistors that were crumbling. I then noticed that the dip switches were so corroded you couldn't move them. I removed  the dip switches and put in jumper wires in the locations I wanted.

Using this guide ( ) I was able to determine with a bit more confidence that the cpu was functioning ( mostly ). Time to test it - again....

I fired up the Hulk and , you guessed it, the same damn thing - looks like it boots but wouldn't coin up or play. I tried disconnecting the playfield switch inputs and jumping out the coin switch, according to the article above, to see if that would work - it did! I heard the dinky Hulk music play indicating a coin had been dropped in. Wait, this means the sound board is working - something I don't have to fix? Holy crap!

The coin up problem must be a wiring or connection issue. I'm assuming the cpu edge connectors are now good so I trace the coin input using the Hulk Pinball manual. The signal doesn't make it to the coin switch. It seems the coin input runs through a large molex plug in the base. When I looked at the molex connector it jumped out and bit me - a large green chunk of corrosion on the exact pin used for the coin wire. It crumbled in my hand..

coin switch molex pin corrosion

I jumped this pin out ( yes, no molex connectors on hand either ) and the machine coined up and actually started!. Now there's perhaps a few dozen problems with the machine - some displays are out, the driver board melted the drop target bank coils, and someone rewired a few switches and coils for no apparent reason. Perhaps this was the jerry rig way around fixing the cpu edge connector pins.

In summary I had 2 primary issues: The first was the slam switch and the 2nd was the broken pin on the coin switch molex. Although it certainly was 'shot gunning' all the rest needed to be done anyway. A slew of secondary issues were corrected by re-pinning the molex.

On the upside it's all downhill from here. I was really afraid I'd have to concede and purchase one of those new cpu replacement boards for the Gottlieb machines ( which are not made by Gottlieb and have no affiliation with the company * )

July 17, 2007

I ordered the drop target coils and will get back to this when they arrive. In the meanwhile I tried to operate them with only one coil - the other was melted so bad it couldn't be re-wrapped. I noticed the 2n3055 drive transistor was getting real hot. Although the coil was firing correctly I noticed 2 volts across the coil when off meaning the 2n3055 was partially biased on. The cause was the pre-driver MPSU45 transistor which must have become damaged due to the corrosion on the molex pins, Gottlieb grounding problems, or the shorting of the drop target reset coil - whichever is unimportant but it was slightly biasing the drive transistor on running it red hot. Because I do so little board work these days I don't have a scope or curve tracer so I have to rely on my DVM readings to test transistors which don't always catch bad/leaky ones. I replaced the MPSU45 with a TIP122, which is not a direct replacement pin wise. This solved the problem. It's at this point I noticed the circuit uses no real protection at all - no clamping diodes - no isolation. The typical way to operate is to use an opto isolator between the TTL and the drive circuit but in the 80's most circuits didn't do it this way for whatever reason ( cost? ). This explains why I've been reading so much about the Gottlieb system 1 damage to cpu boards boards when drivers burn up.

July 19, 2007

Parts ordering time... I found a new site for rubbers ( ) and have ordered enough for Hulk and the 4 other machines on the 'to do' list. I've got two coils on order from eBay for the drop targets and also some 6118 drivers for the 2 bad displays. Incidentally, I made one good display from 2 so now I have 3 good displays and one needing ICs.

To Do

July 21, 2007

Cleaning and waxing went smoothly except for one post which had been previously moved and the hole was very large. I relocated the post 1/4" and everything is fine.

This photo shows the posts and screws before/after cleaning.

Cleaning the posts and screws

On the left is the ball assembly all cleaned up - nice and shiny. On the right is the playfield with pop bumpers removed. I don't normally pull the pop bumpers off unless there's an issue. These were really nasty underneath ( as shown ) and the mylar protectors were damaged. I trimmed the mylars and re-used the originals after cleaning and waxing the playfield.

Ball shooter and pop bumpers

Here's something odd.. It looks like the factory must have had lots of old-stock small flipper bats. Notice the white posts near the top - they're flippers - It's the same on IPDB.

old stock flippers used as posts

Here's the machine to date - all bulbed up, cleaned, waxed, and repaired ( mostly ). I'm still waiting for the rubbers and udn6118 driver chips for display #4 and it looks like display #2 can use a little zap or molex repair. There are maybe 30 bulbs in the head which I'm certain will cook the backglass.

Hulk pinball to date

July 26, 2007

The rubbers and the chips have arrived. I was happy with the price and service from Pinball Life - I'm adding this to the home page. The display ICs ( UDN6118 ) came from - They had an auction on Ebay - 4 chips $20 + $5 shipping. They had 'em - I needed 'em. I've seen these for less but their price was fine for 'need 'em now' - lower than most online sellers. I only needed 2 but ordered 4 because *sometimes* one may arrive defective or incorrect part. I've had this happen with Mouser and other places couple of times - no fault of the supplier - just luck of the draw.

udn6118all gas displays working

2 displays are slightly dimmer than the other 2. There's a fix for this but, having rejeuvinated many CRTs, I'm not so sure I really want to do this as it may ultimately shorted the life of the tubes.

To Do: Clean some miscellaneous cabinet rust. Clean the cabinet exterior and vacuum out the interior. De-rust the legs.

Aug. 5, 2007

The machine is as complete as I'm going to make it for now. I've cleaned up what I could and play tested it vigorously with my grandson. I still have to add a battery - will do when I remember to pick up a battery holder at Radio Shack.

Final Photos:

Hulk Pinball

Hulk Pinball

Hulk Pinball

Aug. 21, 2007

The machine had been playing well. I went in one night to play, turned it on, and had no sound. I had previously cleaned the grounds and the pins on the edge connector so I'm not sure what's going on. I'm borrowing a scope ( yeah, I don't have one ) to see if I've got clock and data movement, etc. All the voltages are present. There are MANY options for getting the sound going but I'd prefer to use the original boards. I may just put in a Gottlieb chime box if I can't find the original board at a reasonable price.

To Be Continued ...