Tony Duell wrote: Good news/bad news. Good news is that the 12v part of the system is work. Bad news is that one of the 28F020's smoked. Here is what I've been able to determine so far: 1) 5V section is fine. 2) -12V section has a major short (measured 0 ohms across it, not the power supply). 3) The flash programming circuit has a problem. 4) The NIC seems to work as the hub now recognizes it but I haven't seen what traffic is on it. Sniffer doesn't show a MAC address or anything. But that may be the sniffer. Conclusion/assumptions: 1) 5V is working, there for the main part of the mother board is unaffected. 2) Fails diags at LAN (7 error lights), may be SQE setting. 3) 28F020 fried but it's for D/L of image from tftp server. 4) -12v is only for RS232, there for short exists in that section. Of course this is kind of weak right now. BTW, the reason I asked the question here is that folks like us (real hackers) tend to want to fix things and have the right kind of software/hardware knowledge for this kind of stuff. BTW(2), this is my $2 ebay find, a Nupon LTS-4 terminal server. When I fix it I'll upgrade it to an 8 by adding the components. I should probably let it go since I also have another terminal server on the way. But old electronics shouldn't just be tossed in the trash, kind of feels wrong (yes I'm out of my mind). -- Linux Home Automation Neil Cherry ncherry(a)home.net http://members.home.net/ncherry (Text only) http://meltingpot.fortunecity.com/lightsey/52 (Graphics) http://linuxha.sourceforge.net/ (SourceForge)

I'll certainly second the statement about the Tantalum cap's. I once had a fire in my AMPRO system because of a shorted Tantalum, and, having seen the smoke emanating from the rear of the PSU (I hd used a PC-style case) immediately assumed the fault was in the often considered flaky power supply (this was in the mid-80's). In the process of prying the grommet with all the various power leads out of the supply case, I stuck a 1/2"-wide screwdriver I was using as a prybar, about 1" into my hand. (think about where you can stick a screwdriver 1" into your hand and not go out the other side ... ) Half a day and over $1k in medical expenses later, I looked at the Little Board and saw the burned spot where the cap had been. If Only I'd looked before I lept . . . <sigh> About a year ago I once again was powering up an old Ampro Little Board, and, sure enough! ... the -12 was pulled down by a shorted tantalum bead. Apparently they do not age well. BTW, AUI uses -12 and +12 from the supply on most cards that support it. The coax gets an isolated negative voltage generated locally on the NIC, generally with a little switcher module. These are handy to hang onto when you're faced with a broken NIC. They generally make a nice -9-volt source for boxes that have no other negative supply, and that's satisfactory for RS-232. Dick ----- Original Message ----- From: Tony Duell &lt;ard(a)p850ug1.demon.co.uk&gt; To: &lt;classiccmp(a)classiccmp.org&gt; Sent: Sunday, August 13, 2000 10:35 AM Subject: Re: [OT] Power and NIC questions fried PS).

What reminds me of the experience I had is the dead short you reported between -12 and ground. A tantalum cap will make it look like that, and, once some current runs through them you find out it's not really a short, since they get hot and catch fire. Once they do that, of course, it opens the short and you can readily see what's up. I don't recommend putting on a higher current supply to do this, however, since traces may go before the cap. Dick ----- Original Message ----- From: Neil Cherry &lt;ncherry(a)home.net&gt; To: &lt;classiccmp(a)classiccmp.org&gt; Sent: Sunday, August 13, 2000 12:38 PM Subject: Re: [OT] Power and NIC questions had a the supply out of prybar, 1" $1k burned <sigh> bead. when source for

Well weirder things have happened but I've managed to get the terminal server to boot up, communicate via a PC/Terminal (send/receive), and to attempt to boot from the aui port on the nic. Seems that I'm now being beaten up by a password! Well I think an eprom burner should take care of that. That and a zapping of the battery backedup static ram. -- Linux Home Automation Neil Cherry ncherry(a)home.net http://members.home.net/ncherry (Text only) http://meltingpot.fortunecity.com/lightsey/52 (Graphics) http://linuxha.sourceforge.net/ (SourceForge)

I agree completely. It's funny how often we see this sort of thing done, though inadvertently. The argument I frequently hear is, "well, I hook up the 5-volt supply to my welder (at 5 volts, of course) and it won't hurt what is supposed to operate at 5 volts . . . Dick ----- Original Message ----- From: Tony Duell &lt;ard(a)p850ug1.demon.co.uk&gt; To: &lt;classiccmp(a)classiccmp.org&gt; Sent: Monday, August 14, 2000 11:23 AM Subject: Re: [OT] Power and NIC questions <snip> part.