Does a tester exist where a logic gate IC can be connected through a clip, to be tested in-circuit, without desoldering it from the board?
I note "in-circuit".
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In my past employment, I worked in an area that looked after a bunch of Data General (DG) minicomputers. In support of that, there was a table set up with what was commonly referred to by staff as the 'board tester'. Faulty cards from the computers were taken to the board tester table.
Step 1: Two long thick power leads (+5V and ground) were connected from the 'board tester' to the card-under-test. The power leads included thin voltage sense wires so that delivered was +5V at the card (not +5V leaving the board tester).
Step 2: The 'board tester' software had library of DG cards, and from that library, the user choose the particular card was under test, e.g. DG p/n 123456.
With that information, the 'board tester' knew:
• What type of chips (e.g, 74LS244, 74LS123) are located at each position (U1, U2, etc.) on the card; and
• Which non-power pins on which chips are tied to ground by the circuit; and (e.g. on U55, pin 6, one of the enable pins, is grounded by the circuit)
• Which non-power pins on which chips are tied to +5 by the circuit; and
• Which non-power pins on which chips are tied together.
Step 3: One would instruct the 'board tester' to start the test.
Step 4: The 'board tester' would then instruct the user to place the IC clip on U1, then the user would inform the 'board tester' that that was done. The 'board tester' would then test U1 (using the knowledge of step 2 above), giving a pass/fail indication on-screen.
Step 5: Then on to U2, then U3, etc.
Largely successful.
The 'board tester' was flexible enough that we could modify the testing logic for a card.
Or we could add new cards (we had to define the testing logic for each chip).
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So, not generic, because the testing logic needs to know the specifics of the circuit, i.e. the type of information in the final three bullet points in step 2 above.