El Dorado City of Gold (Gottlieb, 1984): faults, drop targets and System 80A replacement boards

Is your El Dorado City of Gold by Gottlieb showing scrambled displays, glitching audio, drop targets that won't reset, playfield lamps flickering in unison or random resets? These are the standard complaints of a Gottlieb System 80A machine whose CPU, Driver and power-supply boards are past forty years old. All of them are documented, and battery-free replacement boards install Plug & Play when an original board is past saving.

About El Dorado City of Gold (Gottlieb, 1984)

See it: full photo gallery for El Dorado City of Gold on IPDB (#767) — backglass, playfield, cabinet and flyer scans. There is also a Pinside gallery and owner page.

Released in September 1984, El Dorado City of Gold is the last pinball machine Ed Krynski designed — and Krynski designed most of the Gottlieb games people remember from the 1970s. That alone makes it a game collectors care about. Only 905 units were built, which puts it among the scarcer System 80A titles; the artwork is by Larry Day, with sound and music by Craig Beierwaltes.

The game is a solid-state rebuild of Krynski's own El Dorado from 1975, reusing that machine's playfield layout with a treasure-hunting theme in place of the original western one. Two nice details: the explorers on the backglass were modelled on Gottlieb's own video game artists, Jeri Knighton and Jeff Lee, and the soundtrack runs constant jungle and bird effects under the game — if yours chirps at you, that is the game working.

One cataloguing wrinkle worth knowing before you order parts. Pinside and Kineticist list the manufacturer as D. Gottlieb & Co.; IPDB files the game under Premier; Pinball Rebel says Premier Technology / Gottlieb. All three are defensible, because September 1984 is precisely the handover month: Gottlieb's coin-op arm had been renamed Mylstar Electronics in 1983, Columbia Pictures shut Mylstar at the end of September 1984, and in October a management group under Gilbert Pollock bought the pinball assets and formed Premier Technology. The electronics are System 80A either way.

• Manufacturer: D. Gottlieb & Co. (catalogued by IPDB under Premier)
• Released: September 1984
• Model number: 692
• Production run: 905 units
• Electronic system: Gottlieb System 80A
• Game design: Ed Krynski — his final pinball design
• Artwork: Larry Day — Sound and music: Craig Beierwaltes
• Type: solid-state, 7-digit displays, 4 players
• Playfield: 4 flippers (including two at the top), a 10-bank of drop targets across the top and a 5-bank on the right, pop bumpers upper left and right, no multiball
• Rules in brief: clearing the top bank with the upper flippers lights extra ball; clearing the five right-hand targets advances the bonus multiplier
• Market value: Pinside estimates $1,110–$1,290, with a median asking price around $1,150
• Also in software: Pinball Hall of Fame: The Gottlieb Collection, and FarSight's The Pinball Arcade

The El Dorado family — and a note on the numbers

Krynski's 1975 layout was reworked repeatedly, so if you are buying parts, confirm which machine you actually have. The family runs: El Dorado (1975, model 370), Gold Strike (1975 add-a-ball, model 372), Lucky Strike (1975 add-a-ball for Italy, model 371), Target Alpha (1976 four-player replay, model 392), Canada Dry (1976, France only, model 392C), Solar City (1977 two-player replay, model 393) and finally El Dorado City of Gold (1984, model 692).

Published production figures for that family do not agree, and we would rather say so than pick one quietly. Wikipedia and Kineticist both give 2,875 for the 1975 original and 905 for City of Gold, but they diverge on the rest — Target Alpha is 7,285 or 7,467; Canada Dry 2,885 or 2,994; Solar City 2,525 or 2,634; Lucky Strike 1,013 or 1,015; Gold Strike 675 or 691. Treat any single figure as approximate. Note too that only City of Gold is solid-state: the earlier machines are electromechanical, so no System 80A board fits them.

Why the layout matters for repairs

Two things about this playfield shape the fault list.

Fifteen drop targets. Ten across the top and five on the right make this one of the most target-heavy machines on the system. Drop target banks are mechanical assemblies with a reset coil, individual target switches and a bank-completion switch — far more moving contacts than a typical 80A playfield, and the first place to look when scoring goes odd.

Four flippers. The two upper flippers are how you reach the top bank, and they put more flipper-coil load on the game than a two-flipper machine. Weak upper flippers make the game's main objective unreachable, so they get noticed quickly.

Common faults across System 80A

• Battery corrosion on the CPU board (A1). The original NiCd sits on the MPU and leaks; the electrolyte creeps along traces, eats the edge-connector fingers and attacks nearby parts. It is the most common cause of a dead System 80A board and must be neutralised before any other diagnosis means anything.
• Edge connector contacts. PinWiki names these as the number-one cause of System 80 failures. Clean with a pink rubber eraser; where contacts are divoted, sand lightly and re-tin rather than going to bare copper.
• No common ground plane. These boards are grounded only through their connectors and a daisy chain of wires. As the joints age, grounds float and the machine misbehaves — several solenoids dropping out at once is the classic tell. The fix is the System 80 ground mod: one dedicated ground wire from each board to a common point, tied to the cabinet ground strip.
• Power supply drift. The 80/80A supply — the board with the big heat sink — produces +5 V logic, +8 V display offset, +60 V displays and +42 V status display. Its round header pins crack with heat cycling (square headers are the durable replacement), and the 5 V sags once every board is loaded. Set it to 5.0–5.1 V measured under load.
• Tired logic on the MPU. The 6502 sits at U1; the three 6532 RIOT chips handle the switch matrix (U4), the displays (U5) and the solenoids, lamps and sound (U6). A failed RIOT takes out exactly one of those functions, which is a useful shortcut. Battery-backed RAM sits at Z5.
• Displays missing segments or digits — often just A1J2/A1J3, whose wire colours are notoriously easy to confuse on reassembly.

Faults specific to El Dorado City of Gold

These recur in this machine's threads specifically. Where an owner never reported a confirmed fix, it says so.

Drop targets won't reset

The most distinctive fault on the game, and an intermittent one. Owners describe it as happening every third or fourth game: when either the top bank of ten or the right-hand bank of five is fully knocked down, the bank fails to reset mid-game — but resets correctly when the ball drains.

One owner worked through it the expensive way first, replacing the MPU and the power supply board and inspecting the wiring, soldering and relay switches, without finding anything. The advice that came back pointed somewhere cheaper: the "all targets down" bank-completion switch on each bank. That switch is what tells the game the bank is clear and triggers the reset, and it is a mechanical contact under constant abuse. Check and clean it on both banks, then clean and re-gap the targets themselves. That thread has no confirmed resolution posted, so treat the switch as the prime suspect rather than a proven answer — but note that the symptom pattern fits it: a reset that works on drain (driven by end-of-ball code) while failing on completion (driven by the switch) is exactly what a marginal completion switch looks like.

If the bank never resets at all, that is a different fault: suspect the reset coil, its driver transistor on the Driver board (A3), or a mechanical bind in the bank.

Everything glitching once the machine warms up

A well-documented pattern on this game: after roughly an hour of running, one or two digits on each display go scrambled, the audio glitches at random and all the lamps flash. Switching off for fifteen or twenty minutes brings it back to normal; a quick power-cycle does not, and the fault returns within minutes of a warm restart.

That thermal signature points at connections rather than at a dead chip — things that are marginal cold and open up as the backbox heats. The experienced advice in that thread was the standard System 80 pair: edge connectors first, then the ground mod. The owner's friend suspected connectors, RAM or ROM, in that order, which is the right order. Work methodically: power off, unplug and reseat one connector at a time rather than all of them at once, so you learn which one it was.

Playfield lamps flickering in unison

Reported as the playfield lamps flickering together during play, for anything from a few seconds up to a minute, then returning to normal. The thread is marked solved and the answer was a ground problem — the advice given was to improve, or double up, the ground connections. Whole banks of circuits misbehaving together is PinWiki's named signature of a grounding fault, so this is the ground mod's home territory. Do that before investigating a single lamp circuit.

No attract mode

A messier case, worth describing because the symptoms shift as you work on it. One owner had intermittent zeros across the displays plus a clunking noise, which turned out to be the board rebooting over and over. Reseating the connectors stopped the reboots — and the displays then went blank. A power cycle brought the zeros back, but the game would no longer accept credits or start. Putting the coin door switch into service position produced a normal attract mode, then it reverted.

No confirmed fix was posted. The suggestions were: check the supply voltages, clean the edge connectors with a pink rubber eraser, inspect for cracked solder joints, and check the ribbon cables, which are often worn on these machines. The useful lesson is the pattern itself — symptoms that change every time you touch a connector mean the fault is in the connections, not in a component, and chasing components at that point wastes money.

Won't power up at all, or no coils

Both have their own threads on this game. For a dead machine, work outward from the wall: fuses and their clips (Gottlieb's oxidise, and the added resistance drops the voltage enough to look like a failed supply), then the supply's 5 V, 8 V, 60 V and 42 V rails, then the MPU. For no coils at all while the rest of the game seems alive, go to the grounds — multiple solenoids dropping out together is the ground signature again — and then to the interconnect between MPU and Driver board (A1J4 to A3J1, 33 signals), which is the single most abused harness on the system.

Sound: some effects, no background audio

Owners report a game that makes some sounds but has lost its background audio — a brief sound after the start melody, and flipping cutting the melody off. The moderator response on that thread was a corrupted sound EPROM, read and reburned if you have the means.

For orientation: a System 80A game of this period uses the MA-490 sound board with the MA-488 piggyback carrying a 2716 sound ROM, and the sound signals reach it from the Driver board through Z13, a 7404 hex inverter. So the fault can sit in the ROM, on the sound board, or in the path from the Driver — check that the Driver is actually sending the trigger before condemning the ROM.

Scoring that stops on one target or one bank

If a single target or one whole bank stops registering while everything else works, that is the switch matrix, not the drop target mechanism. On System 80 a switch is identified by its strobe digit plus its return digit, with returns 0 to 7 landing on A1J6-10 through A1J6-17. A whole row or column failing together points at the strobe or return line — a broken wire, a bad pin at A1J6, or the switch-matrix RIOT at U4. A single switch failing points at the switch itself: on this game, one target's blade contacts.

Weak upper flippers

Not a board fault, but it is specific to a four-flipper game: if the upper flippers are soft, the top bank and therefore extra ball become unreachable and the game feels broken even though it is working. Check the flipper coils, their EOS switches and the coil sleeves before assuming an electronic problem. Owners do discuss coil upgrades on this machine; be aware that a higher-power coil increases the load on the same driver transistors.

One thing to know before you buy

Backglasses for El Dorado City of Gold are hard to find. The Pinside index for this game carries a long run of "wanted: backglass" and "backglass help" threads — more than for most System 80A titles, which is a reasonable proxy for scarcity. Given only 905 machines were made, a cracked or flaking backglass is a real consideration when valuing one.

Replacement boards compatible with El Dorado City of Gold

All of these fit a standard System 80A machine, and so fit El Dorado City of Gold. Each is tested before it ships and supported afterwards.

• GottFA80_Plus (Light) — all-in-one CPU + Driver + power supply board, without sound.
• GottFA80_Plus (Full) — the same board with the sound section integrated. Worth considering here given how often the sound EPROM is the suspect.
• Gosof — replacement sound board, with or without voice. City of Gold has no speech, so the no-voice option is the match.
• Godri80 — replacement Driver board (A3). Relevant on a fifteen-target game: the drop target reset coils run through its solenoid drivers.
• Lisy80 — CPU board with web diagnostics. Genuinely useful on this machine, because reading the switch matrix in a browser beats guessing which of fifteen targets has gone quiet.
• GoPOP80 — pop bumper driver board, replacing the original MA-922 / A-19741.

A note on the name: LISY is an independent developer's free, open DIY project — see lisy.dev. The Lisy80 sold here is a ready-to-use board built on it; the project is not ours and the credit belongs to its author.

One compatibility caveat: only the 1984 City of Gold is solid-state. If you have an El Dorado, Target Alpha, Solar City, Canada Dry, Gold Strike or Lucky Strike, you have an electromechanical machine and none of these boards applies. If you are unsure which you have, send us the model number from the cabinet — City of Gold is 692.

Plug & Play installation, battery-free, free tutorials and support. Contact us.

Step-by-step diagnosis

1. Powered off, look before you measure. Remove the NiCd if it is still fitted and neutralise the corrosion it left on the MPU.
2. Clean every fuse clip. Tarnish here mimics a failed power supply.
3. Power supply. Measure the 5 V, 8 V, 60 V and 42 V rails, and set 5 V to 5.0–5.1 V under load, not with the boards disconnected.
4. Grounds, then connectors. Ground mod across CPU, Driver, power supply and sound; then re-pin the oxidised Molex connectors, starting with A1J4 to A3J1 and the switch-matrix connector A1J6. Reseat one at a time so you learn which one mattered.
5. Ribbon cables. Inspect them for wear — a known weak point on this machine.
6. Function by function in test mode. One whole function dead points at its RIOT: U4 switches, U5 displays, U6 solenoids/lamps/sound. Never plug or unplug a display while powered on.
7. The target banks. Check both bank-completion switches, then each target's switch, then the reset coils and their drivers.
8. Warm it up. If the game only misbehaves after an hour, leave it running and retest — a fault that needs heat is a connection, not a component.
9. Final test. Start-up, credits, all four flippers, both banks, displays, a full game. Stuck? The support is free — ask.

FAQ — El Dorado City of Gold (Gottlieb, 1984)

Why won't my drop targets reset?
If it is intermittent and only happens when a bank is fully knocked down — while resetting fine on drain — suspect the "all targets down" bank-completion switch on that bank before anything electronic. Clean it, then clean and re-gap the targets. If the bank never resets at all, look at the reset coil and its driver transistor on the Driver board instead.

My displays go scrambled and the sound glitches after an hour. What is it?
A fault that needs heat to appear is a connection, not a chip. Clean the edge connectors and do the ground mod first, reseating one connector at a time so you find the culprit. RAM and ROM come after that, not before.

Why do all my playfield lamps flicker together?
Whole banks of circuits misbehaving at once is the signature of a grounding fault on System 80 — the owner who reported this on City of Gold resolved it by improving and doubling up the ground connections. Do the ground mod.

My El Dorado City of Gold has no attract mode.
Check the supply voltages, then the edge connectors and ribbon cables, and look for cracked solder joints. If the symptoms change every time you touch a connector, the fault is in the connections — a new board plugged into bad connectors will behave the same way.

I have sound effects but no background audio.
A corrupted sound EPROM is the usual answer, read and reburned if you can. Before that, confirm the Driver board is sending the trigger: the sound signals pass through Z13, a 7404 hex inverter, on the way to the MA-490 sound board and its MA-488 piggyback.

One target stopped scoring. Board or mechanism?
Switch matrix, usually. A single switch failing is the target's own contacts; a whole row or column failing together points at a strobe or return line, a bad pin at A1J6, or the switch-matrix RIOT at U4.

How much is El Dorado City of Gold worth?
Pinside estimates roughly $1,110–$1,290, with a median asking price around $1,150. With only 905 built and backglasses genuinely hard to source, backglass condition moves the number more than you might expect. Our valuation guide has the detail.

Should I remove the original battery?
Yes, and sooner rather than later. A leaking NiCd is the leading cause of dead System 80A boards. Replacement boards run battery-free on non-volatile memory, so settings and high scores survive a power-off with no battery on the board at all.

Useful guides

• All-in-one boards for Gottlieb System 80, 80A and 80B: which should you choose?
• Gottlieb System 80 ground mods: why and how to do them
• Battery leak on a pinball machine: damage, dangers and the permanent fix
• My pinball machine won't turn on: the step-by-step diagnostic
• Pinball electronics explained: MPU, Driver, power supply and sound board
• Understanding the Lisy80 CPU board in five minutes
• How much does pinball repair cost? The price guide
• How much is my pinball machine worth? Value and estimate

See also

• The Games (Gottlieb, 1984)
• Jacks To Open (Gottlieb/Mylstar, 1984)
• Touchdown (Gottlieb, 1984)
• Alien Star (Gottlieb/Mylstar, 1984)
• Ice Fever (Gottlieb, 1985)
• Rack 'Em Up (Gottlieb/Mylstar, 1983)

Sources & further reading

• IPDB — El Dorado City of Gold (#767, catalogued under Premier)
• Pinside — El Dorado City of Gold: production, credits, features, value estimate
• Wikipedia — El Dorado City of Gold: Krynski's last design, rules, family production figures
• Kineticist — the El Dorado family: model numbers and (differing) production runs
• Pinball Rebel — El Dorado City of Gold: model 692, Premier Technology attribution
• PinWiki — Gottlieb System 80/80A/80B repair guide (board designations, switch matrix, sound boards, ground mods)
• Pinball Nirvana thread — "El Dorado City of Gold: drop targets not resetting"
• Pinball Nirvana thread — "El Dorado City of Gold: playfield lights flickering" (solved: grounds)
• Pinside thread — "System 80 — El Dorado: City Of Gold (Everything Glitching)"
• Pinside thread — "El Dorado City of Gold — No attract mode"
• Pinside thread — "El Dorado city of gold sound issues"
• Pinside thread — "System 80 El Dorado City of Gold won't power up"
• Pinside thread — "System 80A no coils will work?"
• Pinside — all 75 forum threads for El Dorado City of Gold (including the backglass hunt)
• Wikipedia — Gottlieb: the Mylstar and Premier Technology timeline
• OPDB — Open Pinball Database

Own an El Dorado City of Gold? Send us a photo and we'll add it here with credit — get in touch.