Looking at a PCB, there are 4 components marked TB1, TB2 etc.

I believe that the markings mean terminal board. What exactly is a terminal board?

Update: Unfortunately I cannot show a picture of the actual components. It looks very similar to a fuse like this. No markings on the component.

Photo of components

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    \$\begingroup\$ Can you show us a picture? Markings aren't always standard, but it would help to see what these components are. \$\endgroup\$
    – Ron Beyer
    Feb 7, 2020 at 13:53
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    \$\begingroup\$ Why did you guess Terminal Board - how do you know it's not tube 1, transistor B1 or Thyristive Biggatron 1? \$\endgroup\$
    – user253751
    Feb 7, 2020 at 13:57
  • \$\begingroup\$ @RonBeyer you are right, I removed my answer. \$\endgroup\$ Feb 7, 2020 at 13:58
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    \$\begingroup\$ It could be terminal block, which is typically a connector which accepts wire connections without solder. Is it a bare PCB? If not, what is/was in those locations? \$\endgroup\$ Feb 7, 2020 at 14:15
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    \$\begingroup\$ @MikeSeeds - Hi, I believe my update to your question captures the essence of your comment. If not, please edit the question to change it, as needed. Thanks. \$\endgroup\$
    – SamGibson
    Feb 7, 2020 at 15:00

1 Answer 1


I might guess they are polyfuses© ® so perhaps TB1,TB2 could be SMD Thermal Breakers


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