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Compaq Portable 286 power supply, there are two identical TO-3 packages labelled "102528" with Linear Tech logo. Anyone know what these are?

Just got a new project, a Zenith 171. Seller described it as failing memory test. I did my usual intake/evaluation and the first two obvious problems I found were: - The PSU sometimes would put out some very low voltages. I traced this to the close proximity of C17 and R44/R45 - any moisture...

I ran the ROM BIOS of a Zenith 286 through an x86 disassembler and I got the following instruction at the reset vector (FFF0) FFF0: JMP 0C252h Looking at location 0xC252 in the code there is a "disable interrupts" command, a "output 0 to port 80h" (post code port) etc, so I assume that is the...

Working with another member here on troubleshooting a Zenith SupersPORT 286 motherboard that won't start up. Getting really into the weeds. We have one broken motherboard and two working ones so we can do comparisons with a logic analyzer. So far we have identified that the keyboard...

I have a BP Microsystems EP-1 eprom programmer on the way, as I have a specifc need to read and program 8042 and 8742 chips. The manual for the EP-1 says that it will program these chips using adapter "HEAD-1A" Does anyone know that the pinout of this connector is? I have the parts needed to...

I was trying to replace the CP-3044 HD with an SD-IDE or CF-IDE adapter and every time I plugged in the adapter and powered the machine on I got a black screen no-start. Even other period-correct HDs had the same response. With the working HD connected (keyed by the blind pin) I did some...

I recently picked up a pair of Zenith SupersPort 286 lugggables and have been getting them fixed up. I have a couple of remaining issues that I was hoping someone might have seen/solved before. In this thread, the external CRT connector: I have the User & Technical manual that lists the...

I recently picked up a pair of Zenith SupersPort 286 lugggables and have been getting them fixed up. I have a couple of remaining issues that I was hoping someone might have seen/solved before. In this thread, the backlight.. The backlight does not work. It is an electroluminescent panel...

I picked up a Zenith SupersPORT 286 laptop and I've been going through doing a few repairs on it. Recapped PSU, CF HD, plastics repair etc, ... My current project is the backlight. I slid the panel from behind the LCD and I can see a physical burnmark on the power lead sealed inside the...

A friend gave me an old specalist video card that is TWO full-length PC card sisteret together as a single unit. Both cards has a PCI connector and it sits nicely in two adjacent PCI slots. It has an external S-Video port and a VGA port. The only apparent connector is a multi-pin proprietry...

I'm trying to replace the original psu in this Mitsubishi MP-3200 386. The original one just puked a month after I recapped it. I will eventually get around to fixing it, but for now I'm adapting a modern PSU. I have all the wires mapped out except one - it's white. On the motherboard side...

I need to adapt a modern psu to my Mistubishi MP-3200 without cutting up the old connectors. This is the only one I don't recognize. Anyone know what it's called so I can try to locate a replacement?

My Mitsubishi MP-3200 386 does not have an IDE controller onboard, but it has an Acculogic sIDE3+. The ROM on the sIDE3 is too old to detect the CF adapter I have, so I am working on XT-IDE. I downloaded and built XT-IDE it from source, and found that the Motherboard has two slots for option...

Working on "Uncle Sherman", my Mitsubishi MP-3200 386. Trying to run down some memory errors. 1024K of soldered 'base' memory on a daughterboard, and 1024mb upper memory that is socketed / populated. Total of 2Mb. I have been trying to use CheckIT 3 to figure out why I often get a message...

No conclusions here, just and observation regarding my black screen C64... I measured the temps of the various chips with a cheap infra-red non-contact thermometer, and found the Kernal ROM to be running at 160F (yikes), and the memory chips to be between 90F and 118F. A subsequent test of the...

Hello all, Still occasionally breaking out the Compaq Proliant that won't POST, and mapping out the board looking for a reason. History: Proliant 1500 Dual P166. On power up there is no sync to the VGA, no post, POSTCard shows nothing at all ("-- --"). The ISA address/data lines show a burst...

Working on "Uncle Sherman", my Mitsubishi MP-3200 386SX-16. Current issue that has resurfaced is that it reliably crashes when certain software tries to put it into protected mode. CheckIT V1: Crashes on "(2) Test EXTENDED (Protected mode) Memory only" Specifically crashes at address...

Hello all, Working on my first C64 / Breadbin / 250407. Purchased as non-working. Getting black screen. More detail below, but for those that want to get right to the question.... Here are a few waveforms comparing the Pin15 output on the VIC chip (luma/sync) to the pin 4 on the AV socket...

Working on "Uncle Sherman", my Unisys-branded Mitsubishi MP-3200 386. Continuing to make progress, and I just got a keyboard added and tested the 3.5" disk drive. If I try to boot from a DOS 6.22 disk I get to the "Starting MS-DOS" message, then a few seconds later the screen blanks and I get...

tl;dr ... Question: Does the Oak OTI067 have a splash screen / initialization message at bootup? More detail: Working on "Uncle Sherman", my Mitsubishi MP-3200 386 from 1988. Before I start up old computers I have a process where I disassemble, test for shorts, visually inspect, capture...