HISTORY:
You may well be thinking "Hell! that's an ancient power supply!" ... but if you dabble with OLD equipment, both ordinary PC and specialised industrial equipment, you may very well come across one of these power supplies. Don't bother going to a computer "shop" to try and get one of these, all you will get is "blank stares" (actually you may get them no matter what you ask!)
Back in the early 2000's this power supply was considered quite a beast and yet, ran very quietly. It was in our original Trace Duplication tower which later was modified to be "reborn" as a media transfer station and then later it morphed into a Win based DAW at one stage (running Zefiro ZA2's and Lexicon Core 2 cards)
While being used for audio work, it was imperative that the system ran acoustically very quietl so the PSU fan noise was extremely important. Just to be safe we actually had the DAW system outside the studio door so that no audio "distraction" to the sound engineer would occur.
Yes, this PSU is old, in fact very old compared to modern PSU's which might only last a rather pathetic 5 years or so - this PSU is well engineered and after all these years, I fired it up yesterday and tested it under load - absolutely no issues with DC outputs or fan noise (in fact I had to shine a light inside the PSU to make sure the blades were rotating - VERY quiet)
Let me explain the "time-line" of this AT power supply
Purchased and supplied with the Trace Duplication tower in 1999
1999 - 2007
Used this PSU in our business for approximately 7 years, around 10 hours per day continous and under 80% load capacity (we had a lot of drives and other devices "hanging off the tower system)
2007 - 2023
Upgraded all of our equipment to nice shiny new (and faster/less latency) machines so the tower had no purpose in life any longer - it was put into the "back room" i.e the "Rest Home" for old peripherals and components. It has been in that room until a couple of weeks ago, yes a long, long time (15 odd years)
I plugged it in, loaded up the DC outputs with as many drives etc I could lay my hands on and measured the DC output voltages .... results are shown below under the heading TESTING
Just so you have no misunderstanding about this power supply, here is some basic information ....
This is NOT an ATX power supply! It predates ATX .... and is called an AT style power supply
DC power is supplied to the motherboard using two separate connectors, one provides the motherboard DC voltages and the other provides the voltages for the motherboard CPU
There is no "start signal" required for the power supply to come to life, as soon as the AC input is plugged AND the DPST front panel switch is operated then the power supply is running and providing all of the DC voltage outputs.
There is an inbuilt cooling fan, the speed of rotation is dependent upon the temperature INSIDE the PSU box - the warmer it gets, the faster it runs.
AT power supplies were in general use from the 1980's until the turn of the century and quite large compared to contemporary power supplies, most commonly limited to around 250W total power output but this power supply was (at the time) at bit more special in that the power output capability is 350W so it is even more bulky than "normal" for an AT power supply.
The PSU is LARGE and if being used in an old system you will need to make sure the size and shape will fit the existing case. One of the photographs shows this power supply installed in the old modified Trace Duplicator case, a high and all steel case - no flimsy sheet metal or aluminium for the Americans!
Sea Sonic Electronics Co. Ltd remains an active designer and manufacturer of both consumer and industrial power products, see their website HERE
So, after that long preamble, let's get down to describing this component ....
SEA SONIC ELECTRONICS Co. Ltd (SEASONICS) - AT style power supply
Made in Taiwan (probably - not stated on the case or labelling)
Model: SSH-350A
Intended for international distribution - both English and German labelling
AC input: 115V or 230V (currently set to 230V)
IEC input (male socket)
Switchable IEC output socket rated to 2A (female socket)
Internal fan rotation speed is controlled by internal temperature
Total supply power capability: 350W
DC output voltages/maximum currents:
+5V 35A
-5V 300mA
+12V 14.2A
-12V 300mA
Output leads (of which there are many!) include:
2x 6 way Molex & 2x 2 way Molex for an old motherboard
8x 4x way Molex for peripheral devices (+5/+12V)
2x 4x way small form Molex for peripheral devices (+5V/+12V) e.g Floppy drives
AC input is switched ON/OFF using a large panel mounting DPST switch which is connected to the PSU via a 1.1m cable
WEIGHT: 2.5Kg
DIMENSIONS:
The overall case measures 212mm x 150mm x 150mm height
Now imagine that box above has a corner "chopped out" - this corner section measures 48mm x 35mm x 150mm height
AC input cable and all of the DC outputs exit from either side of the case
Mounting holes on the rear (where the fan & AC input/output sockets are located) number 4, two of them are 144mm apart and the remaining two are 189mm apart
Distance between the two rows is 130mm
COSMETIC CONDITION:
USED
Clean
Chrome finish is 95% shiny, a couple of light oxidisation spots only.
Some oxidisation around the fan protective grill as well but nothing serious
NO physical damage
NO damage to the power lead (1.1m length) which goes to the ON-OFF switch and the switch is operating fine
TESTING:
While the original tower system was in use this power supply never gave any problems at all, then it has been sitting in the "backroom" for the last 15 years!
While dismantling the tower, I loaded up as many DC outputs as possible and measured the primary DC outputs as:
+5V reads as +4.97V
+12V reads as +11.67V
Fan noise is extremely low, no squeeks or other strange sounds. In fact it was so quiet that I had to shine a light inside the case to make sure the fan blades were actually rotating!
