Hi Folks -
I picked this power supply up on eBay for a good price, and just wanted to put some pictures up in case someone else was considering buying one. When I was researching, I couldn't find many first-hand impressions for this model in particular. That said, these along with the MASTEC power supplies have been prolific throughout my career, even school. Some variant of this design always seems to pop up anywhere I've worked. They're cheap, robust, and fall into a good position between programmable and non-current controlled supplies.
This model is a triple output: 5V/3A fixed, and two independent/series/parallel 0-30V/0-3A channels. Full specifications are here:
http://www.gwinstek.com/en/product/productdetail.aspx?pid=38&mid=53&id=131The layout is pretty standard, but I have to say the displays are great. Very bright, and I appreciate the difference in color between voltage and current.
There's a true hard disconnect switch in front, along with soft control of the supply outputs. Outputs default to OFF when powering the supply on. One really nice feature is when switching between series, parallel, and independent modes, the supply automatically switches the output off before switching. Great to keep you from frying something by accidentally switching modes, or not re-arranging leads before hand.
Also, no need to short the outputs to set your current control: disabling the output shows the current CC setpoint on each display (as seen below):
The fan didn't kick on until I had the supply loaded full out for a few minutes, but it was noisy getting up to speed. I'm not particular about these things, but being a used supply, it may simply need some attention.
The power supply is a nice size (87V for comparison); smaller than it appeared online.
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Voltage and current readings were spot on throughout both independent ranges, series and parallel. Unfortunately the lack of resolution on the display and lack of granularity on the single-turn control pots makes this supply unsuitable for powering low voltage cores and the like. However for my intended use, it's perfect for supplying regulators, split DC bus rails, etc:
Start-up unloaded and short-circuited was satisfactory. Unloaded:
Shorted:
Nice size multi-tap toroid:
Airflow is directed into the heatsink, around the toroid, and out vents on the two sides, towards the front.
Channel 1 arrangement with rectification, power amps, tap selection relays, etc.
Channel 2, with the addition of a power NPN, presumably for the fixed +5V/3A output. This flying lead arrangement seems a bit lazy, but otherwise the internal construction is on par with the price point this supply hits (a good one, in my opinion).
There are a plethora of adjustments surrounding the front panel PCB, each labeled accordingly.
A full adjustment procedure is attached to this post. The supply actually maxes out around 32V/3.3A per channel.
So that's all for now. Hopefully someone will find this of some use, even if just for the pictures. I am still trying to track down a solid schematic and/or service manual, if anyone has any leads!
Best Regards,
James