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Wow, haven't been here in over 10 years. Hope everyone is doing well!
So I haven't touched my 12th Edition of Scott Mueller's Upgrading and Repairing PC's in close to 5 years. But here it is, back on my desk...
The reason? Well I dug up an AT&T Model 6286/EL WGS Desktop
I pulled the cover, it's stamped September 1990 on the bottom. Massive amounts of dust! Massive! Both 6-pin power connectors were unplugged. One SIMM removed and laying in the case.
Plugged in the connectors, I thought I was slick remembering the "black wires touching" rule, but alas, they're keyed... Pushed in the line voltage power switch, PSU fan comes alive, front panel power LED lights green, and the floppy drive has some activity. POST beep.
My next task was giving every inch of the computer a dusting and cleaning. Here's the drive bay/PSU portion of the LPX-style case cleaned a bit:
Motherboard removed and dusted a bit:
It's a Western Digital WD286-LPM12 board. Integrated IDE Controller, Paradise Video, PS/2 keyboard & mouse headers:
Phoenix BIOS chips, dated 1990:
The glorious 12.5Mhz 286 CPU, an AMD N8OL286-12/S, unfortunately soldered to the board:
4 x 30-pin 80ns 256k SIMMs with Parity, by Texas Instruments (TM256GU9B). I installed the fourth removed SIMM and it's registering fine. Have not run any memory tests yet:
3270 Terminal Emulator Card, a DCA IRMA 005026:
Quantum ProDrive 40MB IDE HDD:
So I had it down to the bare chassis. Cleaned everything pretty well, and then blew out the PSU with some duster spray, and reassembled. Plugged it in and turned it on. Soft, fast-paced, rhythmic beeping from the PC speaker, the power LED blinking. It would do this in 2-3 second cycles. No video output, no drive power... I opened up the PSU. No bulging caps, nothing out of the ordinary. I think that first startup in 25 years did it in...
I rigged up a hack temporary solution to get the machine to power up and it worked quite nicely:
I am looking for a replacement LPX PSU. The bottom right mounting hole is not in the standard location, and the case has clips to secure the PSU, so I may be looking for a used identical model:
Back to the testing! Here's the machine POSTing:
I was quite certain this BIOS would require a floppy to access the SETUP program, but sure enough, it's built in. Ctrl + Alt + Insert accessed it.
Speaking of keys, here's what I found along with the machine. An AT&T branded Keytronics Professional KB3270 Keyboard with DIN to PS2 adapter. Missing one key as shown:
The BIOS is complaining about the RTC losing power. Any suggestions on battery replacement for this board? Until then, every boot means accessing the BIOS SETUP first to set the HDD type.
I did a full PKZIP backup of the hard drive contents and intended on using it, but it since has failed the "initilization" during POST, so I've installed a more modern 4.3GB Seagate Medalist IDE drive, limited by the 504MB BIOS limit, which is just fine with me.