• Please review our updated Terms and Rules here

IBM PC XT 286 Doesn't Turn On

I

itsvince725

Experienced Member
Joined
Nov 26, 2016
Messages
447
Location
Pennsylvania
I just got a XT 286 today, which I understand to be a pretty uncommon find (it was mixed in with a stack of 5150s and 5160s, though I did see two PC 3270s in there). It's a bit rough on the outside and has no hard disk but the inside is clean and in pretty good shape.

However, despite looking really clean...it doesn't power on. Flipping the power switch does nothing. I'm sure the power supply is to blame somehow, but is it possible there's also something else preventing the machine from powering on?
 
Last edited:
1. Where did you see TWO PC 3270's?
2. Take everything out of the machine; all cards and disconnect hard disk/floppy disk drives to get a minimum configuration then power it on... see what happens...
 
itsvince725 said:
However, despite looking really clean...it doesn't power on. Flipping the power switch does nothing. I'm sure the power supply is to blame somehow, but is it possible there's also something else preventing the machine from powering on?
Click to expand...

Yes--it isn't uncommon for a capacitor on the motherboard to go short, which will keep the PSU from starting up.

Try running the power supply with the motherboard disconnected and only a hard drive for load.
 
lyonadmiral said:
1. Where did you see TWO PC 3270's?
2. Take everything out of the machine; all cards and disconnect hard disk/floppy disk drives to get a minimum configuration then power it on... see what happens...
Click to expand...

1. A store called Kemner's Surplus Warehouse in Pottstown, Pennsylvania. He's got all kinds of stuff. Macs, a bunch of IBM stuff including XTs/5150s, a few ATs, and stacks of PS/2s, a bunch of TRS-80s and CoCos...just tons of stuff. Some of his XTs are really rough and basically scrap, but the 286 I bought and the 3270s I saw on the one stack were still in good shape. Mind, these systems are incomplete and thus the original 3270 software is gone, though the coax cards may remain.

2. I will have to do that tomorrow. Fortunately there's only two cards in the machine so it won't take that long.
 
I was wrong, there was three cards! A floppy/hard drive controller, a combination parallel/monochrome video card, and what I assume is a CGA card (it says COLOR GRAPHICS). The CGA card turned out to be the issue, as the machine powers up fine with the other two cards.

Can someone link me a nice service manual? I wanted to pull the floppy drive to check how the board looks underneath but couldn't figure it out...
 
There were many, many manufacturers of color graphics cards (CGA); the schematic for the IBM-made version is in the IBM PC Technical reference.

But you probably don't need the tech ref; just check out all of the tantalum electrolytics on the board. They have a tendency to degrade and short with age, often giving up the ghost with a "bang!", but not always.
 
Oh no, not a manual for the card (I want to put in like a 256KB VGA card anyway!) but a service manual for the XT itself! That will come in really handy if I have any more problems with the machine.
 
Lots of IBM 5162 (XT/286) info at minuszerodegrees.net

itsvince725 said:
... and what I assume is a CGA card (it says COLOR GRAPHICS).
Click to expand...
"COLOR GRAPHICS" is seen on the IBM CGA card. Photo at [here].

itsvince725 said:
The CGA card turned out to be the issue, as the machine powers up fine with the other two cards.
Click to expand...
Chuck(G) said:
But you probably don't need the tech ref; just check out all of the tantalum electrolytics on the board. They have a tendency to degrade and short with age, often giving up the ghost with a "bang!", but not always.
Click to expand...
On the IBM CGA card, C8 is the tantalum capacitor that often fails.

itsvince725 said:
Can someone link me a nice service manual? I wanted to pull the floppy drive to check how the board looks underneath but couldn't figure it out...
Click to expand...
The drive may be held in by a screw that is inserted/removed via the underside of the case.
 
I thought that, but it's a half-height drive with an empty bay underneath. Maybe the whole assembly is screwed in?

I'm not sure yet what I'm going to use for a hard drive solution but I should put something in the gaping hole where a full height hard drive once resided. Maybe another full height drive or a 3.5 floppy and a half-height drive...
 
Take a close look--often, half-height drives were accommodated by screwing them onto side-plates that slid into the full-height slot.

At this stage, I don't really trust any time-appropriate MFM drives. I marvel at how a machine that I have with a 30MB Quantum Q540 drive keeps chugging along. I've got it backed up against the day that I know is coming. You may want to consider picking up a 16-bit IDE controller (often comes with a floppy controller as well) and then just use CF card or DOM and forget about spinning rust altogether.
 
itsvince725 said:
I thought that, but it's a half-height drive with an empty bay underneath. Maybe the whole assembly is screwed in?
Click to expand...

On my XT 286 the HH floppy drive is secured on a HH frame with blanking plate on the front with plates like [ These ], Remove the 2 screws 1 on the inside and 1 underneath in the recessed hole and the whole assembly can be withdrawn from inside the case.
 
Last edited:
itsvince725 said:
I'm not sure yet what I'm going to use for a hard drive solution but I should put something in the gaping hole where a full height hard drive once resided. Maybe another full height drive or a 3.5 floppy and a half-height drive...
Click to expand...
I've got an IBM 0665-38 30MB drive that runs well if that's of interest. It's originally from a 5170. It hasn't seen any use in the last 25 or so years other than to occasionally test it.

I'm not that all far from you so it might not need to be shipped.
 
The drive is carried in a sub-assembly that is held in the chassis by a screw underneath, in a small well or indentation.

-CH-
 
Malc said:
On my XT 286 the HH floppy drive is secured on a HH frame with blanking plate on the front with plates like [ These ], Remove the 2 screws 1 on the inside and 1 underneath in the recessed hole and the whole assembly can be withdrawn from inside the case.
Click to expand...

Thanks!

I should probably grease up the rails on the floppy drive before I try putting disks in, and being able to get the drive out of the machine would make that a lot easier!

Wait...since this is an AT-class machine on the inside, can't I use a conventional IDE controller card instead of an XT-IDE?
 
As Chuck said, Yes, But note: When you remove the original MFM/Floppy controller from the XT 286 and replace it with a IDE controller, On boot up the IBM XT 286 bios throws a 601 error because it expects to find the original controller ( Like the 5170 does ), Then you got to press F1 to continue. I found this annoying So I swapped out the original IBM Bios for an AWARD one and problem solved. Also note, I found that the XUB is incompatible with the IBM XT 286 bios ( Like the 5170 ).
 
XUB = XTIDE Universal Bios

Yes BIOS chips are socketed at locations U34 and U35 on the XT 286 Motherboard.
 
I guess that means I'll need two BIOS chips then.

First, I'll have to get a hard disk and OS for this thing. I was thinking maybe version 4.01 as it fixes the problems with IBM DOS 4.0 and supports both 1.44MB floppy drives and >32MiB hard drive partitions, but maybe I should just do MS-DOS 5.0.
 
You must log in or register to reply here.
Back
Top