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Help with a 386 power supply

post #1 of 4
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At work I am using an old 386 to run a 20 year old UV-Vis spectrophotometer (Varian Cary 1E) and as of late the computer will not start every time. When I flick the power switch, nothing happens although upon turning the switch back to the off position results in the Num lock light on the keyboard lighting up briefly. I checked all of the physical connections and everything seems to be in place. The PSU currently in this box is a 245 W no-name brand. While I'd love to replace the instrument entirely, it is not an option. Sadly, the university has already disposed of all old form factor computers and didnt think to hold anything in reserve for those of us that can not just drop a few grand (software licenses are expensive!) to migrate to newer systems. Ultimately I'd love to migrate this instrument to a Pentium II or III based system but the lack of proper software is currently holding me back.

The actual inquiry: Does anyone know how to configure a modern power supply's leads to match the configuration of this "ancient" form factor? I took a peek around the internet this afternoon and failed to turn up anything helpful (maybe I just dont know what I am looking for).

Any thoughts would be helpful and appreciated!
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Brynhildur
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post #2 of 4
maybe it can be repaired?
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post #3 of 4
386 era computers used the AT electrical standard, which is very different from the modern ATX12V and even the obsolescent ATX electrical standard.

386 systems were more +5V oriented, so your best bet would be to get an ATX 1.3 PSU, since those were designed for heavy +5V/+3.3V load. I would recommend the Zippy RF5300-v2, but Jameco no longer carries it. This ATNG-made Rosewill would be an acceptable replacement:
http://www.newegg.com/Product/Produc...-006-_-Product

Then get the connectors you need and go by this pinout:
http://en.wikipedia.org/wiki/AT_form...ower_connector


I do have concerns, however. The -12V rail was nearly obsolete even by the late 1990s, and in modern systems can provide only a token amount of power. -5V was removed from the ATX12V spec entirely in 2003, which is part of why you need an ATX 1.3 unit. I have no idea how much -5V and -12V current an AT system draws, but it may be that no ATX power supply can provide it.
Edited by Phaedrus2129 - 3/8/11 at 1:03pm
post #4 of 4
Check local flea markets, computer shops, etc. to see if you can find and old 386/486 system for a few bucks.
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442
(15 items)
 
Q6600
(14 items)
 
Piece O' Crappola
(13 items)
 
CPUMotherboardGraphicsRAM
Q9550 E0 DFI LanParty LT P35-T2R 2 x HD4670QT512P CF Patriot PVS24G8500ELKN 
CoolingOSMonitorPower
Stock pfsense Acer H233H Antec EarthWatts 430 
CaseAudio
custom onboard 
CPUMotherboardGraphicsRAM
Q6600 B3 Lapped @ 3.4 GA-EP45-UD3R EVGA 9600GSO 384m 96SP 4G (2x2) Patriot Viper PC2-8500 
Hard DriveOptical DriveCoolingOS
80g Maxtor, 320WDC. 320Seagate NEC ND-3550 & LiteOn CM Hyper 212+ w/PP Blademasters XP Pro SP3 
MonitorPowerCase
Acer H233H Rosewill RG630-S12 NZXT BetaEVO 
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80Gig WDC SATA NEC ND3540A Win 7 Ultimate 64bit/XP Pro Acer H233H 
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Antec Earthwatts 430 none 
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