HP 3488A teardown, disassembled for parts
[IMSAI Guy] has an old HP 3488A switch control unit that he wants to disassemble for parts (see video below). The 3488A is pretty basic when it comes to HP test equipment - a chassis that can hold various types of relay cards and is programmable via GPIB. He notes up front that these are plentiful and inexpensive on the used test equipment market.
Around the back of the unit is a card holder that accepts up to five option cards providing
4×4 matrix switching SPST on/off switching switch signals on a common bus VHF switching Digital I/O signaling
The teardown is an interesting insight into the solid engineering design of 1980s HP test gear. The option boards are well shielded and have an interesting rear panel connector that distributes signals to the screw terminals and provides strain relief. The brain of the switch was a Motorola 6809 and connectivity was provided by an Intel 8291A GPIB interface chip. The power supply is solid and many of its parts can be reused on other projects, such as the transformer and a beefy 20W DC-DC converter by ST. [IMSAI Guy] also scores a bunch of latching relays from the option boards which will no doubt come in handy for future projects.
These types of programmable relays can be very useful when building automated test devices. There were other solutions for that too, at the time. Metrabyte (bought by Keithley, bought by Tektronix) was a company that made a whole line of switch interface modules that plugged into your PC's ISA bus. Omron also offered similar products. Have you ever needed programmable relay banks for your projects? If so, let us know your solution in the comments below.
[IMSAI Guy] has an old HP 3488A switch control unit that he wants to disassemble for parts (see video below). The 3488A is pretty basic when it comes to HP test equipment - a chassis that can hold various types of relay cards and is programmable via GPIB. He notes up front that these are plentiful and inexpensive on the used test equipment market.
Around the back of the unit is a card holder that accepts up to five option cards providing
4×4 matrix switching SPST on/off switching switch signals on a common bus VHF switching Digital I/O signaling
The teardown is an interesting insight into the solid engineering design of 1980s HP test gear. The option boards are well shielded and have an interesting rear panel connector that distributes signals to the screw terminals and provides strain relief. The brain of the switch was a Motorola 6809 and connectivity was provided by an Intel 8291A GPIB interface chip. The power supply is solid and many of its parts can be reused on other projects, such as the transformer and a beefy 20W DC-DC converter by ST. [IMSAI Guy] also scores a bunch of latching relays from the option boards which will no doubt come in handy for future projects.
These types of programmable relays can be very useful when building automated test devices. There were other solutions for that too, at the time. Metrabyte (bought by Keithley, bought by Tektronix) was a company that made a whole line of switch interface modules that plugged into your PC's ISA bus. Omron also offered similar products. Have you ever needed programmable relay banks for your projects? If so, let us know your solution in the comments below.
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