A4983 Carrier Board - ENABLE input 1 ohm to ground

I bought 4 of these boards recently, and I’m just putting them through their paces now after some basic testing.

They will only supply about 0.5A without a heatsink, so I have arranged them in a square and strapped a video card cooler to the top, with channels cut to avoid shorting the Vbb capacitor, and the current pots sticking out the sides.

While testing this arrangement I discovered that on one board, there was a mere one ohm of resistance between enable and ground! Luckily enable is negative-asserted. On the other 3 boards, there is about 900k. According to the schematic, this should be around 100k due to R6. None of the boards show any continuity between this pin or ground and the heatsink.

I have yet to ascertain whether this is due to something I’ve done, or if the boards came like this, although I can’t imagine what I could have done to cause this.

I’m pretty sure these boards are still usable in my application with this issue.

Any ideas how this might have happened, or what I should check or try?


On the A4983 chip the enable pin is right next to a ground pin. Can you follow the enable trace along the board and look to see if there is a solder bridge between the EN and GND pins? The electrical test we do tests that the enable pin is not connected directly to ground. Is it possible that you could have bridged the pins when soldering something near the chip? If you don’t care about using the enable feature, there shouldn’t be any danger in having it connected to GND.