I was about to strip this old amplifier for parts and saw how beautifully constructed it was internally. It seemed only right to record its passing with a quick teardown:
It's an AMS F.I.D./N.P.D. amplifier , used for flame ionization and nitrogen-phosphorus detection in gas chromatography (about which I know very little). I wasn't able to find any documentation on the net.
The grubby and deceptively dull front panel.
That zero adjustment knob is connected to a ten-turn potentiometer, and the knobs are all high quality collet types.
The back:
The TO-3 can is a 7815 15V regulator.
Inside - a Eurocard sporting an intriguingly solid shielding can, linked to a backplane via the usual DIN 41612 connectors:
The 64-way connectors are severely underutilized, each sporting about eight connections.
And beneath the shield:
The money shot. An Analog Devices 310J electrometer op-amp module, linked to the detector inputs via Teflon coaxial cable, Osmor reed relays and Welwyn high voltage resistors (rated at up to 28 kV). The input resistor values range from 5 megohms to 5 gigohms.
Handsome rear panel wiring, showing the numbered input connectors and an earthing point:
...of which there are many:
The backplane, which has the power regulation circuitry and another four fuses to add to the two on the back panel:
The main circuit board out of the case:
And finally, a sad little salvage pile:
(This in addition to a hefty transformer and three circuit boards.)
How much did this jewel of electronics engineering cost? I picked it up off the grass at the Dunstable Downs electronics car boot sale mentioned recently by Mike Harrison (mikeselectricstuff). The owner had abandoned the attempt to sell his selection of old lab equipment and was giving it away...
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