Today's trip to the surplus store yielded an interesting piece of equipment. This is a High Yield PM-150 particle counter. You won't see many of these! And this is built like a friggin' tank.
We start out with the views from the front and back. There are slots for four detecting heads. The safety interlock has a shorting plug on it, which is in series with a keyswitch. I'm not entirely sure what is so dangerous about this piece of equipment that it needs all that safety. The front power switch is really beefy, and the thing is built to last. Taking the rear cover off, we expose three boards and a power supply. The bottom two boards are acquisition boards, though there is circuitry on the bottom board for the keyswitch. The top board is the actual computer board.
The power supply is just two commercial power supplies and a DC-DC converter.
Everything pops out until you get to the front panel, at which point you have to dig in and unscrew four screws throughout the entire, very hefty, case. I didn't bother pulling off the front panel board, because it obviously was just an LCD and a few contact switches.
There is a lithium battery and a very well built alarm on the computer board. The battery was bulging a bit, but it's probably over 20 years old and long gone, so I didn't think much about it.
There is absolutely no surface mount on this device, in fact, it reeks of late 80s, and still, its construction impressed me so much that I put it back together, made sure it's working, and put it on ebay.
On another note, old laptop docking stations (the kind with the monitor platform designed for CRT monitors) make an excellent oscilloscope/test equipment stand. I picked up two.
Next teardown will likely be a casio keyboard I'm going to rip the guts out of and replace with something much more powerful.
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