Epoxy Blob Excised Out Of Broken Multimeter, Replaced With A QFP

Bridget J. Sims

The black blobs on cheap PCBs haunt those of us with a routine of getting matters aside when they are unsuccessful. There is no aspect amount to look up, no pinout to probe, and if magic smoke is launched from the epoxy-buried silicon, the full PCB is toast. Which is why it issues that [Throbscottle] shared his journey of restoring a vintage multimeter whose epoxy-covered one-chip-multimeter ICL7106 heart created an inner reference fault. When a multimeter’s inside voltage reference goes, the meter naturally results in being worthless. More affordable multimeters, we bin, but this one particular arguably was really worth reviving.

[Throbscottle] does not just present what he achieved, he also demonstrates exactly how he went by the system, in a way that we can discover to repeat it if at any time required. Guidance on eliminating the epoxy coating, isolating IC pins from shorting to recently uncovered tracks, matching pinouts amongst the COB (Chip On Board, the epoxy-coated silicon) and the QFP packages, meticulously attaching wires to the board from the QFP’s legs, then examining the connections – he went out of his way to make the trick of this mend available to us. The Instructables UI doesn’t make it evident, but there is a large selection of substantial-good quality pictures for each and every stage, as well.

The multimeter actions after all over again and is again in [Throbscottle]’s arsenal. He’s got a prolific history of sharing his procedures with hackers – as far back again as 2011, we have included his information on reverse-engineering PCBs, a skillset that no doubt created this repair feasible. This hack, in transform proves to us that, even when going through the void of an epoxy blob, we have a shot at fixing the factor. If you wonder why these black blobs plague all the inexpensive products, here’s an intro.

We thank [electronoob] for sharing this with us!

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