POWMAX PS Tester

We’ll take a brief moment today and take a look at a power supply tester. This unit is built by Powmax, and consists of a simple module that contains LED indication lights and a couple of high wattage resistors to provide a simulated steady load condition. A basic picture and very sketchy technical info may be found on the Powmax site.

This unit consists of a single plastic module, appx 2.5 inches wide, 4 inches deep, and 1.5 inches tall. The top of the unit consists of a clear plastic cover that allow you to view the LED test indicators. You can also clearly see the test circuit board that contains various electrical components and two large resistors. One is marked 5W15ohm, and the other is 5W10ohm. The circuitry on this board simulates a steady loaded condition for the power supply, and also provides the proper connections to allow the supply to power up (i.e., as if it were switched on).


The first question might be… why? It’s simple really – I rebuild and refurbish a lot of computers each year to donate to charitable causes such as underprivileged children and families in my local area. Often, this involves taking several computers and making them one. Power supplies are often a point of failure in older systems that frequently came with 150 or 200 watt power supplies. I simply do not have time to do a lot of troubleshooting and tracking down power supply problems. So, when I recently was in the retail showroom of CMI Computers picking up a case for review I saw this unit on their shelf out of the corner of my eye and purchased it for about $15.

As you can see, I go through a LOT of power supplies. Some of these are known bad and are destined to have their fans stripped out of them. Some of them are known good. Some of them I haven’t had time to check.


With tester and power cord in hand, I fired up some power supplies and tested them. And of course, as expected, there were some bad and some good. The indicator lights are simple – there are 6 green LEDs and a single red one – if the red LED lights up, the supply is definitely bad. The others consist of a main “good” green LED, and one each for the following voltages: +12V, -5V, +5V, -12V, +3.3V.


There was only one minor problem – one mini-ATX power supply gave some unusual results – NONE of the LED slit up. After doing a little research on the web, apparently mini-ATX power supplies don’t always use a –5V lead, and this can give screwy results. I don’t normally use these underpowered supplies anyway, so this wasn’t a big deal.

Conclusion

This is a basic unit, so don’t expect a lot of frills. It only performs one function but does it well; just plug it in, which makes it impossible to screw up the operation. The indicators are pretty straightforward. I’d like to see a voltage meter or similar, but I guess that’s what my multimeter is for – which I didn’t have time to do in the first place anyway. For it’s intended function, this power supply tester works just fine. I’ll give it 4 out of 5 stars only because the documentation and background info is so sparse (not that you really need it anyway).

Added: October 31st 2003
Reviewer: Insulglass
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