Just to be clear: Jesus A. Diaz of Elizabeth, reports he has an "IBM 386 PS/2 PC" that isn't booting up, and he describes the limited operations it performs on power up. Namely, the fan runs but nothing else, no LED lights no sounds. There's also something he calls "a screen" - maybe a CRT monitor? - that shows the literal words "NO SIGNAL". I have some suggestions to diagnose things further. Warning: proceed at your own risk on these suggestions. Also: I don't know everything, and I'm not an "official" in any way of VCFed or MARCH. But I think it's possible the "motherboard" has failed in some way, rather than the power supply. 1) I don't know if this model computer has its own internal CRT and monitor circuits; and if they are powered by the same DC power supply as the 368 computer. If "the screen" is an external and modern LCD monitor, those are perfectly capable of showing text messages with no computer inputs at all. If "the screen" is an integrated 1990 CRT monitor on a 1990 IBM computer, my guess is "it's not smart enough". Jesus should search the Web for IBM documentation for his exact PC model and see if it offers more diagnostic information, and if operation of the monitor to show *that message* suggests his AC to DC power supply is operating on the computer side. The IBM brand of 386 PS/2 PCs had some pretty good documentation about diagnosing problems. It would be good for Jesus to confirm the exact model and IBM model number of his PC, for anyone wishing to help him. 2) Same deal with that fan. Maybe something else powers that fan. See what documentation says. 3) A simple means to test some of the computer's DC power operation, is to pull the DC power connector from the floppy drive or the hard drive, and use a voltmeter to measure the 5 volts and 12 volts. The connector has four pins, two are ground and one each for 5 and 12 volts. Documentation for these devices will describe the connectors and where the voltages are. Typically the center two pins are "ground", the pins at either end are power. It's harder work, to measure voltages on the PC motherboard, or on the DC power cable. I don't suggest pulling the DC power cable from the motherboard. Without a connected power load on that supply, it may *cause damage*. I'm not sure. Be careful inside your PC, anything you do is at your own risk. 4) related to 3) maybe he can hear the hard-drive spin up when power is applied. He may have to work hard to listen for that. Possibly the floppy drives will spin, but that's not always true if the computer is not functional and or there's no floppy in the drive. Point being: if the DC power supply appears to function, then it's the motherboard. Not much else is left. After Jesus does some of this testing and work, and gets familiar with some of the inner features of this PC, another Web search on that model *and* specific problems, may yield more discussions on the Web about repairing one. Possibly it will lead him to some online sale of a motherboard, power supply or matching computer. Also: Jesus might look at archived previous messages in this vcf-midatlantic list, about the occasional workshops offered at InfoAge (in Wall NJ). Possibly he'd like to bring his PC for *his own work* to test and repair. Read prior discussions to see how that works. They are not "we will fix your PC" workshops, please be clear about that. https://lists.vcfed.org/pipermail/vcf-midatlantic/ Good luck with resolving the IBM 386 PC issues. Regards Herb Johnson -- Herbert R. Johnson, New Jersey USA https://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net