Definition
A bench power supply is an adjustable, regulated DC source used on a workbench to power a board under test. Its defining feature for repair work is independent control of both voltage and current. In constant-voltage (CV) mode it holds the set voltage and lets the load draw whatever current it needs; when current reaches the set ceiling it switches to constant-current (CC) mode, holding current steady and dropping voltage instead. Most modern units show a CC indicator or change colour when this happens.
Why the current limit is everything
That current limit is the single most important safety feature when bringing up a repaired hashboard. By setting a conservative current cap, a technician can apply power to a board with an unknown fault without instantly destroying it or the supply. If the board has a short circuit, the supply slams into CC mode and the current simply pegs at the limit rather than dumping unlimited amps into the fault. A board that should idle at a fraction of an amp but immediately hits the current limit is signalling a short before any further damage is done.
Using it to diagnose a hashboard
The bench supply is the starting point of structured hashboard diagnosis. Power the board through the limited supply, watch the current draw, and interpret it: near-zero current may mean an open enable line, while a pegged current points to a short. From there the technician probes each voltage domain to localise the fault. Slowly raising voltage while watching current also helps find a shorted component by the heat it generates, which a thermal camera or a fingertip can locate. It is the safest way to wake a board up.
It works hand in hand with the voltage domain, the multimeter, and the short circuit in any repair workflow.
In Simple Terms
A bench power supply is an adjustable, regulated DC source used on a workbench to power a board under test. Its defining feature for repair…