LGP-21 photographs

This page will remain somewhat disorganized, until I'm far enough along in the restoration for order to appear. For now they're grouped simply by what I was doing at the time.

(Here are some photos of the cards, and some detailed photos.)

Photographs from the initial disasembly. There's a lot of seemingly pointless detail here, but might help solve problems with broken wires, rebuilding the rotted foam air seals, etc.

Chassis, mechanical and assemblies
Overall view of CPU cabinet.
Overall view, from rear.
Overall view, from rear.
Operator control panel. See Programmers Manual for details.
Operator control panel, door closed.
Overall view of CPU cabinet, cover removed (normally tilts forward, removed for examination). Rotating memory on left, Memory Controller PCB, mounted vertically along left edge of memory just visible, two 7-pin mini tube connectors to memory read amps on memory mounting plate. Power supply lives under the memory, card cage to the right.
Overall view of the guts, cover removed, control panel assembly open showing top of Flex controller PCB.
Top view, cover removed.
Inner control panel assembly, covering top of card cage, open.
Rear I/O connectors.
Mercury tilt switch under thermistor mount, wired to; presumably disables overheat when cover open?
Wiring under front control panel.
Wiring under front control panel.
Rear connectors.
Inside of cabinet showing foam air seals.
Foam air seals inside cabinet.
Cards installed in cage, connectors attached. May or may not be correct configuration (but backplane is a plain buss).
Overall view, right side, cover removed.
View of backplane, power supply below, memory removed. Mercury electro-chemical elapsed-time meter visible; seems unreadable, maybe exceeded full-scale?
Backplane detail.
A "field ECO", where ECO is "Engineering Change Order". In other words, a factory screwup; the thermistor meant to monitor card cage temperature is shielded from some hotspot on the Flex controller PCB by this taped-on piece of teletype paper.
Rear view, rear panel dropped down.
Inside rear panel, connector wiring.
Bottom of main chassis.
Display head
Display head assembly. Basically a simple oscillograph, this is not a data display as we know it today. More detail on this will follow.
Poor photo of the display head front panel.
Display head guts.
Display head guts.
Display head guts.
Rear of display head.
Rotating memory
Rotating memory, overall top view.
Rotating memory, head-mounted diode switches.
Rotating memory, FOO
Rotating memory, FOO
Rotating memory, motor.
Memory controller unfastened, showing connectoring. Big caps are power supply; contactor and AC capacitor are for memory motor, barely visible as black vertical cylinder behind other components.
Memory controller, detail.
Memory motor wiring detail (disassembly).
Side view of memory assembly. Memory (platter) is enclosed, but not sealed/gasketed, so I ahve to assume dust/grit infiltration. Will be restored by professional disk-data-recovery people.
Memory assembly, detail. Unfortunately out of focus, but there are plexiglas-head assemblies placed around the axis, each shifted to cover the 64 tracks.
Memory assembly, detail. Bad photo.
Memory assembly, detail, clearly showing head assemblies and read amps.
Logic cards
Arithmetic logic card.
Flexowriter control logic PCB.
Flexowriter control logic PCB, solder side (wave soldered).
Memory controller logic PCB.
P and Q Register logic PCB.
Phase control logic PCB.
Punch and reader interface logic PCB.
Card cage
Card cage detail.
Card cage air inlet.
Card cage guides, dust and wear inside; cards missing?
More of the same.
Power supply
Top view of power supply under memory, memory removed.
Power supply.
Power supply.
Power supply.
Power supply.
Power supply.
Random
The LASL property list showing the LGP-21 as a line item.
The LASL property list showing the LGP-21 as a line item.
The LASL property list showing the LGP-21 as a line item.
LGP-21 nomenclature plate, rear of unit.