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ISA Voltage Regulator Cards?
stripey357 asks: "I'm trying to install a Dialogic Gammafax card in Pentium-based SCO unix box, and I've run into a problem. The power supply for this box doesn't supply -5v to the ISA, and that's the voltage the Gammafax wants. Do they still make ISA voltage regulator cards that can reg -12v down to -5v, or would it be easier to replace the power supply?"
Not sure if this will work or not...
If it is just that card that needs it, and you know which pin it is on the ISA card, you might be able to do it yourself, with a little work:
The power supply should have a -12 volt line (or even a -5V line, which is easier) - find the pin(s) on the ISA card that need the voltage, trace each one back to a solder pad (or you might have to scrape the trace). Cut the trace with an xacto knife to keep voltage flowing into the motherboard (unless you know that it is routed properly - better safe than sorry). If you need to scrape the trace, do it with the knife as well. Apply some solder, add the wires you need, bring 'em together at one point, and hook up the -5V if you have it from the PS, or if you only have -12V, used a -5V regulator (sorta like the 7805, which is a +5V regulator - they make the opposite, can't remember the part number).
Of course, this invalidates all warranties, and it could cause other problems - it is a hack, plain and simple, I am just offering it to you as a possibility and learning advice - don't blame me if your motherboard/fax card/power supply blows up...
I hope this helps... Good luck!
Reason is the Path to God - Anon
c) isn't an option a lot of the time. yes, SCO is utter and complete shit, but iBCS just doesn't work a lot of the time lately. It's fading into obscurity as everything gets ported over natively.
(when it does work, it's a beautiful thing, though. one of my favorite things we did with it was run a logistics package; the software vendor didn't realize it was a linux box, but they did call us up when they modem'd in and 'ps' didn't work (SCO uses a SysV ps, the one on there was BSD-only, since updated).)
iBCS also has a bit of a problem with some security setups. all that is immaterial, however, because for all intents and purposes, SCO usually Just Works.
Do they still make ISA voltage regulator cards that can reg -12v down to -5v?
You're looking for a 7905 regulator, provided the card does not require more than 1A. These regulators are quite common LSI devices used in hobbyist electronics, they can be found at Radio Shack. Several firms manufacturer 7905's, here are some datasheets:- Fairchild
- Micrel
- Microsemi
Installation is relatively simple. Pin 1 connects to ground, pin 2 to -12V, and pin 3 to the -5V line (this is the output). 7905's are often in a TO-220 package which allows you to screw on a heatsink if needed. Be sure to apply thermal grease to increase heat conductivity.Tired of free ipod spam sigs? Opt ou
Is the motherboard designed without any way to power the -5V line on the ISA bus, or does the power supply not provide it?
I see even classic Slashdot is now pretty much unusable on dial up anymore.
You make a good point, but that was why I suggested cutting the trace, and soldering "above" the cut.
However, I do like your solution - much sneakier in case something goes wrong...
Reason is the Path to God - Anon
The above is the best solution proposed so far, provided that your motherboard actually has the traces for the -5V bus. If the power supply doesn't provide that voltage, they may have decided to save a little money by not including it. Does this beast use a standard power supply to motherboard connector--AT or ATX type?--or something proprietary?
I see even classic Slashdot is now pretty much unusable on dial up anymore.