Rock (Gottlieb, 1985): faults, diagnosis and System 80B replacement boards

Is your Gottlieb Rock showing garbage on the displays, booting but refusing to accept credits, running with dead solenoids that come back when you wiggle a plug, or playing no sound at all? Rock is the game where Gottlieb System 80B begins, and it carries the two weaknesses that define the early part of that run: a fragile ground board on the transformer panel, and a CPU with a daughter card whose solder joints crack. Modern battery-free replacement boards fit Plug & Play — but on this machine in particular, fix the grounds first.

About Rock (Gottlieb, 1985)

See it: full photo gallery for Rock on IPDB — translite, playfield and cabinet shots. There is also an owner photo gallery for Rock on Pinside.

Rock shipped in October 1985 with an original rock-concert theme rather than a licence. John Trudeau designed it, Larry Day did the art, John Buras wrote the software, and the sound and music came from Ken Hale with David Thiel — which matters, because on a game about a concert the music is the game. 1,875 were built.

Rock is the start of System 80B. The alphanumeric displays that define the rest of Gottlieb's 1980s output arrive here, replacing 80A's seven-digit numeric tubes, and PinWiki writes its board-revision ranges as "Rock through Spring Break" — Rock sits at one end of a hardware generation, which is why some of its faults belong to a specific group of games rather than to 80B as a whole.

Pinside's trivia also credits Rock as the first machine to use a translite rather than a screened backglass — a printed, backlit plastic sheet instead of paint on glass. A translite is cheaper to reproduce than a painted backglass, but Rock translites are sought after and there is a steady run of wanted ads for them on the forums.

The playfield is a four-flipper layout, unusual for the period, with an upper 1-2-3-4 playfield, a centre five-bank, four return lanes and A-B-C lanes for the multiplier. Spinners are where the points are: a lit spinner is 10K a spin, 20K during double scoring, and the slingshots change which one is lit. Bonus runs to 150K with a 5X multiplier, and both carry over between balls.

• Manufacturer: D. Gottlieb & Co. (by this point owned by Premier Technology, which is how IPDB lists later games)
• Release date: October 1985
• Production run: 1,875 units
• Model number: 697
• Electronic system: Gottlieb System 80B — the first game on it
• Game design: John Trudeau
• Artwork: Larry Day
• Software: John Buras
• Sound: Ken Hale — music: Ken Hale and David Thiel
• Sound board: MA-766 — display: MA-644
• Players: up to 4, alphanumeric displays
• Playfield: 4 flippers, 9 drop targets, 1 spinner, upper playfield, no pop bumpers
• Theme: rock music / concert

Rock Encore, and the versions built abroad

Gottlieb followed Rock with Rock Encore in April 1986, and the two are the same machine underneath. Encore was sold both as a dedicated game — IPDB lists just 245 of those, which makes it genuinely rare — and as a conversion kit for an existing Rock: an art-and-sound update consisting of a replacement photo translite and three new sound ROMs. Don Marshall joined Larry Day on the Encore art.

That matters if you are buying parts. If your Rock has been through an Encore conversion, the sound ROMs on the MA-766 are not the ones a Rock ROM set will give you, and 80B sound ROMs are the hardest part of these games to source. Check the labels on the ROMs before you order, and keep the set you have.

Two more machines share the Rock playfield under other names: Punky Willy, built by Joctronic in Spain in 1986, and Top Sound from ManilaMatic in Italy in 1988. As with the foreign rebuilds of other Gottliebs of this era, the electronics are not necessarily Gottlieb electronics — open the backbox and photograph the boards before assuming a System 80B replacement will fit.

Common System 80B faults

The board designations used by the manual and by everyone on the forums: A1 is the CPU, A2 the power supply, A3 the driver board (lamps, relays, solenoids), A6 the sound board. The CPU-to-driver interconnect is A1J4 to A3J1, and it carries 33 signals.

Four things account for most System 80B failures. Connector contacts come first: PinWiki calls poor contacts the number one reason these games misbehave, producing intermittent voltages, lamps or coils locked on, and random resets. Grounds come second, and they are a design problem rather than a wear problem — the boards have no ground plane and share ground only through connectors and daisy-chained wires, so one bad ground can lock on coils and relays and destroy transistors and chips on the way. The battery on the CPU board leaks and corrodes the traces around Z5, the 5101 CMOS RAM that holds audits and settings; on 80B a failure here reports as ERROR- Z5 in the self-test, though that message can also mean a chip-select or address-line fault rather than a dead 5101. And the 80B +5 V supply, which is a separate board with no crowbar circuit, has two known weak points: the LM338K regulator can fail high and take other boards with it, and the 500 Ω 1 W adjustment pot is failure-prone and worth replacing on sight. Reflow the J2 header pins while the board is out.

Displays on 80B are the MA-644. The diodes CR1 to CR4 rectify 32 VAC down to −45 V and −15 V, and when one fails it can burn a foil trace that was acting as a fuse — repairable with a jumper. VR1, a 1N4737A 7.5 V zener, causes ghosting or dim characters when it fails short. (The later MA-999 display uses a 1N4739A instead, so do not swap zeners between the two boards.)

Faults owners actually report on Rock

The transformer-panel ground board — the Rock fault

This is the one to know. Gottlieb put a small ground board on the transformer panel, and the version fitted to the games from Rock through Spring Break uses 9-pin Molex connectors. PinWiki calls it the least reliable of the designs outright, and it gives a diagnostic you can run in thirty seconds: if unplugging that connector and rotating the plug makes dead solenoids start working again, the ground board is your fault. Owners describing instability on Rock keep landing in the same place — ineffective grounds near the transformer, cured by redoing them with solid, tight connections.

The proper fix is to bypass the board entirely and crimp the grounds straight to the transformer chassis with ring terminals and a #8 screw. Do this before you buy a single board, because a bad ground here will make a brand-new CPU behave exactly like a faulty one — and can damage it.

Garbled displays, then a game that boots but will not start

A Rock owner on Pinside described a machine that worked for an hour, then put garbage on both displays with only a few playfield lamps lit. After some work it booted — lightshow running, drop-target coils firing — but the score and credit displays read zeros, the high-score displays were blank, and it would not take a credit or start a game. The battery had not leaked and every fuse was good.

The advice from experienced 80B hands was consistent. First, treat a garbled display as a symptom, not the cause: pull the display connector and the game should still boot normally without it. If it doesn't, the fault is upstream. Second, suspect the CPU daughter card — cracked solder joints there are a classic 80B failure and produce exactly this half-working behaviour. Third, do the unglamorous things properly: fibreglass eraser on the MPU card edges, contact cleaner in the edge connectors, and measure the MPU voltages rather than trusting them.

There is a second mechanism worth knowing in this family of symptoms. On the MA-766 sound board, the display unit can hold the external reset line low and stop both of the sound board's processors from starting — one documented repair was cured simply by disconnecting the display. If your Rock is silent and its displays are misbehaving, those two faults may be one fault.

No sound, or sound only at full volume

Rock's MA-766 sound board is a two-processor design: an R6502 at N1 with a DAC at E2, and a second CPU at T3 driving two AY-3-8912 synthesiser chips at H4 and K4. The halves are largely independent, so divide and conquer — a blinking LED on the board tells you the N1 side is alive.

Before any of that, check one thing: the sound board's amplifier runs on ±12 V derived from the solenoid voltage. No solenoid supply means no amplifier power, and a game with working coils can still have a sagging solenoid rail. "No sound at all" and "sound only at maximum volume" both point at the amplifier, volume control and speaker before the digital side. Elsewhere on 80B, a heat-failed 74LS04 clock divider and a buffer on the driver board have both been found behind wrong, slow or missing sound.

The hard part is spares: 80B sound ROMs are scarce and expensive, and genuine AY-3-8912 chips can be incompatible because of different ID numbers baked in. Keep your originals and label them before they leave their sockets.

Controlled lamps that will not alternate

Rock's 10,000 lamps failing to alternate is a reported fault, and it is a driver-board story. Controlled lamps on System 80 run through MPS-A13 or MPS-U45 transistors on the A3 board, numbered so that lamp n is driven by Q(n+1) — L12 by Q13. The lamp data lines are shared by every 74175 latch on the board, so one stuck lamp is usually a local transistor or latch, while all the lamps misbehaving points at the shared lines, the grounds or the supply.

The backbox fluorescent tube

Two problems with one cause: the starter in the backbox fluorescent fitting throws enough electrical noise to disrupt start-up, and the fitting itself gets in the way when you install a modern board. Converting the backbox to LED solves both.

Replacement boards compatible with Rock

Every board below is tested before it ships and supported afterwards, with free technical help.

• GottFA80_Plus (Light) — all-in-one CPU + Driver + power supply, without sound. This is the one for Rock. It covers the CPU and driver side, brings a modern power supply in place of the LM338K board, and removes the A1J4/A3J1 harness as a failure point.
• GottFA80_Plus (Full) — the same board with sound integrated. Note the 80B audio limitation below before choosing it.
• Godri80 — replacement Driver board (A3), if you would rather keep your CPU and replace the lamp, relay and solenoid side.
• Lisy80 — replacement CPU board with web-based diagnostics, which is a real advantage on a game with no error codes at boot. Lisy is an independent developer's free DIY project, documented at lisy.dev; we supply and support the board.
• Gosof — replacement sound board for System 80 and 80A; 80B support is currently limited to a few titles, so see below.
• GoPOP80 — pop bumper driver board, replacing the original A8 board (Gottlieb part A-19741). Rock's playfield is listed without pop bumpers, so you will normally not need this one.

About Rock's sound: replacement-board audio support for System 80B currently covers only a few titles (Bounty Hunter, Chicago Cubs Triple Play, Tag Team). Rock is not among them, so the plan here is GottFA80_Plus Light on the CPU and driver side, and keep and repair the original MA-766 — on a game whose theme is music, arguably the right answer anyway. An audio solution is in preparation; contact us to be told when it lands.

Step-by-step diagnosis

1. Powered off, inspect the CPU. Look for battery residue and corrosion around the Z5 socket and remove the battery if it is still fitted. Check the daughter card's solder joints under a light — cracks there are the classic 80B fault.
2. Test the transformer ground board. Unplug the 9-pin Molex on the transformer panel and rotate the plug. If dead solenoids come to life, bypass that board and crimp the grounds to the chassis.
3. Do the rest of the grounds. A wire from each board's ground to a common point, tied to the cabinet ground strip.
4. Measure the 5 V at the CPU, under load, at the CPU's own pins. Replace the 500 Ω pot on the +5 V board and reflow its J2 header pins.
5. Isolate the display. Pull the display connector: the game should boot normally without it. If it does not, stop looking at the display. Never plug or unplug a display while the machine is powered.
6. Clean the edges and re-pin. Fibreglass eraser on the MPU card edges, contact cleaner in the edge connectors, re-pin oxidised Molex housings.
7. Then the sound. Solenoid voltage first, then volume control, speaker and amplifier, then the board's LED to see which half is alive.
8. Final test. Start-up, credits, each coil, each lamp, each display, then a full game. Still fighting you? Get in touch — support is free whether you buy a board or not.

FAQ — Rock (Gottlieb, 1985)

Which replacement board does a Rock need?
GottFA80_Plus Light is the usual answer: it replaces the CPU, driver and power supply in one battery-free board. Lisy80 is an alternative on the CPU side with web diagnostics. Keep the original MA-766 sound board for now. Send us photos of your boards and we will confirm.

My Rock is unstable and solenoids drop out.
Check the ground board on the transformer panel first. Rock is the first game with the 9-pin Molex version, which PinWiki rates the least reliable design: if unplugging and rotating the plug revives dead solenoids, bypass that board and crimp the grounds directly to the chassis.

My Rock's displays show garbage or stay blank.
Pull the display connector — the game should still boot. If it does, the fault is in the display or its feed; the MA-644's CR1–CR4 diodes and a shorted VR1 zener both cause dim, ghosting or dead characters. If the game will not boot without the display either, suspect cracked solder joints on the CPU daughter card.

My Rock boots but will not accept credits or start a game.
Reported more than once on this machine. Clean the MPU card edges with a fibreglass eraser, contact-clean the edge connectors, measure the MPU voltages against tolerance, and check the daughter card. System 80B gives no error code at boot, which is exactly where a Lisy80's diagnostics earn their keep.

My Rock has no sound.
Start with the solenoid voltage: the MA-766's amplifier takes its ±12 V from the solenoid supply, so no solenoid rail means no amplifier. Then the volume control, speaker and amplifier. The board's LED tells you whether the N1 processor side is running. One documented case was the display holding the sound board's reset line low.

What is the difference between Rock and Rock Encore?
Rock Encore (1986) is the same machine with new artwork and new music. It was sold as a dedicated game — only 245 were built — and as a conversion kit for an existing Rock, consisting of a replacement photo translite and three new sound ROMs. If you are buying ROMs, check which version your machine is running.

Is Rock a rare pinball machine?
Not especially: 1,875 were built. Rock Encore, at 245 dedicated machines, is the rare one. Boards are shared across the System 80B range, but translites and 80B sound ROMs are the scarce items.

Should I keep the original battery?
No — remove it. A battery-free board uses non-volatile memory, so settings and high scores survive being switched off and the biggest single cause of dead System 80B CPUs goes away.

How long does a replacement board take to fit?
Installation is Plug & Play: a few minutes with no soldering, with free tutorials and support.

Useful guides

• Gottlieb System 80 ground mods: why and how to do them
• Backbox fluorescent tube in the way of your board? The solution
• How to install a replacement board: the Plug & Play guide
• Repair or replace a board: which makes sense for your machine?
• How much is my pinball machine worth?

See also — the other System 80B machines

• Raven (Gottlieb, 1986)
• Hollywood Heat (Gottlieb, 1986)
• Genesis (Gottlieb, 1986)
• Gold Wings (Gottlieb, 1986)
• Monte Carlo (Gottlieb, 1987)
• Spring Break (Gottlieb, 1987)
• Ice Fever (Gottlieb, 1985) — the last System 80A game

Sources & further reading

• IPDB — Rock (#1978)
• Pinside — Rock specs, credits and trivia
• Pinside — Rock forum index
• Pinside — "Gottlieb Rock System 80b, I need some help for a friend"
• PinWiki — Gottlieb System 80/80A/80B repair guide
• Gottlieb System 80B sound boards — MA-766 teardown and repair notes
• Kineticist — Rock (production, model numbers, variants, rules)
• Pinball Rebel — Rock Encore and the conversion kit
• lisy.dev — the independent Lisy project
• OPDB — Open Pinball Database

Own a Gottlieb Rock? Send us a photo and we'll add it here with credit — get in touch.