17 September 2007

Tektronix 7A13: broken relays

Relays sit on sockets, so it's very easy to test them outside the original location. Pinout is printed on one side and, before you worry, they're reversible. Surprise: they have 8 pins per side, but row spacing in just 1 pin, so they don't fit on the breadboard as an IC would. So I built an adapter...

If you notice my adapter has 4 pins on one side and only 3 on the opposite: it's because I ran out of pins. But these Tek beauties are reversible, so 5 pins would be enough.

Result of testing 2 relays: out of total 4 switches, they all show continuity in the rest position and only one in the switched position. All others do "click" but don't close the contact. #@£!!

These DPDT relays are Tek 148-0034-00, 15V 600 ohm. No chances to get a direct and new replacement.

But the 7A13 plugin has two other relays with the same part#, used to reduce the bandwidth to 5 MHz. The default position (relays in "rest") is "full BW", that is what I am more likely to use (RF vs. LF). I did not check these K480 and K490 for proper operation, but a self-transplant restored 2x and 5x V/div ranges.

If no other relay is available, use a short jumper to close the contact of interest and live with it.