Space Fortress Restoration


I had already acquired a NOS Hantarex MTR-V 20" black & white vector monitor a few years ago to use to build a Space Fortress. I'd also acquired game PCB's, a marque and then recently had the good fortune to find a complete power plinth & wiring loom courtesy of Andys Arcade. What was missing was a cabinet, control panel, monitor glass and monitor surround.

Whether this project could be considered a restoration or new build is unclear - the parts are all original but the actual base cabinet would be an early Quasar that utilized the same cabinet artwork as Space Fortress. I'd always planned to restore a laminated and converted Quasar to use for this project but discovered that the laminate conversion could not be successfully undone. The cabinet was also in rough shape overall. Instead, I had previously completed a Dambusters restoration that was based on a Quasar conversion in which the base cabinet was in excellent condition. Since the Dambusters was a conversion anyway and is not a space themed game fitting its cabinet, the plan was to "move" Dambusters into the woodgrain cabinet to become a British game in a typical British pub/chip shop woodgrain cabinet. The empty Quasar cabinet could then be used for the Space Fortress restoration.

15/05/2019 - Dambusters restoration

Dambusters in Zaccaria Quasar upright - left Dambusters in Zaccaria Quasar upright - right

The base Dambusters restoration was completed in 2019.

09/01/2022 - NOS Hantarex MTR-V monitor

Boxed Hantarex MTR-V monitor Hantarex MTR-V monitor Hantarex MTR-V monitor chassis

The Hantarex MTR-V 20" black & white vector monitor inside the box was in clean, complete new condition.

Hantarex MTR-V monitor

Two cables were provided with the monitor that ended in bare wires.

09/01/2022 - Space Fortress wiring loom assessment

Space Fortress power plynth & wiring loom

Overall the power plinth was complete but with moisture damage to the plywood base and rust on the metalwork. The wiring was surprisingly complete, including the coin door and control panel wiring with some remaining labels for the signals. Whoever removed it did a thorough job considering future re-use.

Space Fortress monitor power

Both power connectors for the vector monitor were present on the wiring loom so there was no need to use the ones in the monitor box.

Space Fortress game PCB connectors

The game PCB connectors comprised three connectors for audio PCB, main PCB power & main PCB control (coin and controls). There should have been a fourth connector for the video cable from the game PCB to the monitor that was missing.

Space Fortress control panel connectors

The control panel loom was present and partially labeled. Along with it was a 9-pin square block connector that wasn't accounted for in the Space Fortress manual. Closer inspection found this to be a non-Zaccaria modification to separate the control panel.

Space Fortress credit PCB connectors

Both sides of the credit PCB wiring loom were present. Only the coin door light cable had been cut a little short and would need patching.

Space Fortress 1B1126 regulation PCB

Space Fortress & Pirate use a modified version of the 1B1126 regulation PCB that substitutes +15V & -15V for the monitor in place of the +12V and -5V used on other games - hence the warning labels (that it would blow up other raster games).

10/01/2022 - Main board signal connector

Game PCB connectors TE Connectivity 280387-2

The Zaccaria Space Fortress game PCB used different connectors than the Cinematronics Star Castle version. One of those connectors was a 2 x 15 pin AMP plug for the control panel inputs. The matching PCB connector for that plug still exists, TE Connectivity 280387-2.

13/01/2022 - Power cable repair

New power cable Power cable repair

A 6ft standard computer power cable was trimmed and spliced in to replace the original cut power cable.

13/01/2022 - Fuse cleaning

Mains input fuse Low voltage fuse block Fuse contact cleaning

All the fuses showed signs of corrosion. The fuses were lightly sanded with fine paper and the fuse holders polished with a wire brush Dremel.

15/01/2022 - First power on

Space Fortress power supply & wiring 18V tap phases 36V combined AC

First power on revealed that all the power rails were working, +5V, +15V and -15V all looked good with no load. On the Hantarex MTR-V power inputs the 28VAC and 35VAC were also present.

The initial plan was to build a Zaccaria Space Fortress to Asteroids adaptor to support running Asteroids initially for testing and also allow an option to use the Cinevectron reproduction game PCB in future. There were a couple of problems to solve with that:

An external audio amplifier was straight forward to solve - the woodgrain cabinet had one for Mr. Do! that could be reused. The 36VAC wasn't directly provided but there were two 18VAC taps from the Fortress main transformer used for the +/-15V DC. The plan was to tie the two 18VAC inline to become 36VAC. The Fortress manual didn't annotate the phase of the two taps so a scope was used to compare the two taps to determine their phase and how they should be inlined. No cuts would be needed - an intercept connector between the 1B1126 and transformer input would be used to inline and tap off the 36VAC for the adaptor cleanly. The following table shows the 1B1126 AC connector pinout and tap:

Pin Colour Voltage Phase Tap
6 br/wh 18.0V * centre
5 br/wh 18.0V 36V
4 gr 10.5V
3 gr 10.5V *
2 bl/wh 18.0V centre
1 bl/wh 18.0V * 36V

The centre tap configuration was verified on the scope as 40.5VAC sine wave no load.

18/02/2022 - Coin door harness

Empty coin door Zaccaria Scramble coin door harness Coin door harness & credit PCB

Since Quasar doesn't use a 1B1145 credit PCB the coin door harness had been moved over to the woodgrain cabinet. A 1B1145 based coin door harness was included with the Space Fortress cable set and a photo from a Zaccaria Scramble was used as a reference to complete it by adding the microswitches and splicing in the door lights.

1B1145 credit PCB bypass Coin door harness installed

The 1B1145 credit PCB wasn't working so the bypass hack was applied and the harness was installed onto the coin door.

15/03/2022 - Control panel tear down

Mr. Do! Quasar control panel - front Mr. Do! Quasar control panel - back

The Mr Do! converted Quasar control panel from the woodgrain cabinet would form the base for the Space Fortress control panel.

Control panel overlay Control panel

All buttons, joystick, and harness from the Mr. Do! conversion was removed along with the universal control panel overlay to leave a blank panel with a few leaf switches. A large cut out had been made to support the joystick that would need to be repaired.

18/03/2022 - Empty cabinet

Empty Quasar upright - left Empty Quasar upright - centre Empty Quasar upright - right
Empty Quasar upright - inside Empty Quasar upright - inside

Restoration was paused for 2022 Northwest Pinball and Arcade Show preparation.