0
\$\begingroup\$

How can I identify this component on a PLC board that has gone bad? Surface mount, unidirectional, G is the designator, 060 (090?)

It measures as an open circuit with a multimeter on a bad board and on a good board. It appears to be connecting the ground connection on the input power side of the board to a ground plane that other components are connected to on the low power side of the board. The ground plane goes over to the ISO224 on the low power side of the two isolated power supplies (large black boxes, P2 (H2412S-2W) and P3(WRA2415CS-3W))

Every other component on the board seems to be ok but I haven't come into contact with a component like the one circled. I am about to add nominal control power to investigate further.

enter image description here

enter image description here

\$\endgroup\$
1
  • \$\begingroup\$ for future questions it would be useful if you included 1. Brand. 2. Model. 3. The function of the module. 4. What pins you think the device is connected to. 5. As much of the schematic as you can trace out for the relevant section of the board. \$\endgroup\$
    – Transistor
    Aug 23, 2023 at 17:28

1 Answer 1

0
\$\begingroup\$

That really look likes a GDT. It looks a lot like this one: GDT. GDT protect from high voltage transient. They usually fail short, so that could very well be your issue. Finding the right value for a replacement might be hard.

\$\endgroup\$
5
  • \$\begingroup\$ Yeah that looks like it and makes sense considering its measuring as an open, where it is in relation to GND and other components. I guess its probably still good \$\endgroup\$
    – user298907
    Aug 23, 2023 at 17:29
  • \$\begingroup\$ Well, measuring in circuit resistance is always misleading. Unless you have de solder it prior to your measurement, I wouldn't conclude anything of the sort. \$\endgroup\$
    – Julien
    Aug 23, 2023 at 17:31
  • 2
    \$\begingroup\$ @Julien It's 'unlikely' it would be shorted and measure open in-circuit. You'll always get a measurement that's accurate or lower than the real resistance unless there's some residual voltage mucking up the measurement. \$\endgroup\$ Aug 23, 2023 at 17:40
  • \$\begingroup\$ In most case it is true that you would measure the lowest resistance, but if their is an other power source, you might get erroneous reading in both direction. \$\endgroup\$
    – Julien
    Aug 23, 2023 at 17:43
  • \$\begingroup\$ if it is that GDT, the making 090 implies part 4532-091-LF \$\endgroup\$ Aug 23, 2023 at 22:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.