aplmak
Experienced Member
I'm an avid Altos collector. I dug out of one of the closets an Altos 586T to begin working on. Cleaned it all up, recapped power supply, rebuilt tape drive, cleaned floppy drive. I have a bunch of other Altos machines so been through this process before. So my first issue was a resistor blew up in the tape drive.. maybe because the pcb was touching the housing I am not sure. I found a bad tantalum cap and replaced that and the resistor and now it seems to boot up fine (the tape drive does it's initialization properly).
Now I have spare 586 boards but there are various versions.... I never focused too much on the 586/986. I have a working 586/986 with the port expansion taking it to I think 12 serial ports. That machine works fine.
So this is what I get at boot... after boot it takes about 10 seconds (it's doing it's boot test). It comes back that it was successful.. I place the utilities disk in the drive and it begins to load the ADX utilities and then I get a message ***FAULT***. I did try another floppy drive and same thing, I've spent hours and hours at this.. swapping out various parts.. removing extra stuff and keeping only the necessities. So I've spent a lot of hours troubleshooting even taking out the 8086 processor, and various other IC's. I've also tried to swap out my working motherboard but that one is a different version.. and even a spare motherboard flipping IC's between the two. and SAME THING. I have this sneaky feeling it could be one of the 64K 16 pin memory chips. There's 72 and unfortunately they are soldered in. I've ordered some sockets and I will begin to remove all of those 64K chips and put sockets in. I do have a chip tester so once I get them out I will give them a test. Thank god I have a de-soldering gun as well.
I just thought I'd run it by the crew here if anyone has an idea of what they think it might be. Keep in mind it post tests just fine.. No errors. It's not until it begins to load off the floppy drive. The controller board has two led's and they indicate if there is an issue. They are solid red which means the board checks out and is running normally.
Here are some photos of the issue as well as the reference manual courtesy of Al Kossow's hard work. I'd be grateful for any hints you all might have.
You can see in the second photo it recognizes the utility diskette and the version information. But then the floppy drive fails.. and that little box above the ***FAULT*** is normally loaded before the utility starts up. So it is loading... very odd.. The only thing I can think of is memory... it's trying to load into RAM and failing..
I've also burned some different 64K ROM Chips to try various versions I have.
Now I have spare 586 boards but there are various versions.... I never focused too much on the 586/986. I have a working 586/986 with the port expansion taking it to I think 12 serial ports. That machine works fine.
So this is what I get at boot... after boot it takes about 10 seconds (it's doing it's boot test). It comes back that it was successful.. I place the utilities disk in the drive and it begins to load the ADX utilities and then I get a message ***FAULT***. I did try another floppy drive and same thing, I've spent hours and hours at this.. swapping out various parts.. removing extra stuff and keeping only the necessities. So I've spent a lot of hours troubleshooting even taking out the 8086 processor, and various other IC's. I've also tried to swap out my working motherboard but that one is a different version.. and even a spare motherboard flipping IC's between the two. and SAME THING. I have this sneaky feeling it could be one of the 64K 16 pin memory chips. There's 72 and unfortunately they are soldered in. I've ordered some sockets and I will begin to remove all of those 64K chips and put sockets in. I do have a chip tester so once I get them out I will give them a test. Thank god I have a de-soldering gun as well.
I just thought I'd run it by the crew here if anyone has an idea of what they think it might be. Keep in mind it post tests just fine.. No errors. It's not until it begins to load off the floppy drive. The controller board has two led's and they indicate if there is an issue. They are solid red which means the board checks out and is running normally.
Here are some photos of the issue as well as the reference manual courtesy of Al Kossow's hard work. I'd be grateful for any hints you all might have.
You can see in the second photo it recognizes the utility diskette and the version information. But then the floppy drive fails.. and that little box above the ***FAULT*** is normally loaded before the utility starts up. So it is loading... very odd.. The only thing I can think of is memory... it's trying to load into RAM and failing..
I've also burned some different 64K ROM Chips to try various versions I have.
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