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AT&T 6300 mobo troubles

Y

Yzzerdd

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Oct 20, 2006
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Boston, MA
Well some of you may remember awhile ago I mentioned one of my 6300s died. I suspected the power supply, as it had those symptoms(I.E. resetting randomly, HD parking automatically, like it does when powering down, even though PC was on) so I tossed it into the closet and called phooey on it. Last night I decided to experiment. I pulled a known good mobo out of my secondary PC(the other 6300) and swapped the mobos, so I could test a known good mobo with a suspected power supply. To my amazement, it worked perfectly. I checked all of the switches and chips on the board, and it all checks out. I guess the board just randomly died. I know the video is good, though, seems I used that with the testing. At least now I know. If anyone needs any chips from the 6300, let me know. I have everything for offer except the CPU-3Z and the NPU i8087. I have memory chips I pulled that totals to 387KB, and will fit in two banks of memory. I even have the BIOS, V1.1. So if anyone has a similar problem with the 6300, don't jump to the power supply!

--Ryan
 
Well, if you had have left it all together, I probably could have fixed the motherboard for you. I manage to fix a few a week.

Right now I'm working on a VIP 486 mobo for no other reason than they weren't around very long before VLB was dumped and PCI became the standard.
 
I wonder what the problem could be? I still have all of the chips, most of which I remember where they went. The others I can figure out by modeling them from my other AT&T motherboard. Hmm... By time I ship the thing from Texas to Canada and back, I would have paid enough shipping and fees to get my AT&T system(just system, nothing else) down here.

--Ryan
 
That was the same thing that happened with mine. You might wanna open the system unit, and make sure the power plug is inserted into the video board good, and then check the motherboard(on the bottom of the unit) to see that those connections are good as well. If you can't fix it, I would be more that happy to buy the drives and cage off of you.

--Ryan
 
Oh, and sorry to "double post" but there is one more thing you should try. Make sure the dip switches are set right. the settings are self-explanatory, and can be found in the booklet "AT&T 6300 users guide." If you don't have the manual, or the settings, PM me, and I will scan it and post a link here in the thread.

--Ryan
 
OK, here are the pictures. I had to put them on PhotoBucket, as they were too big. They are in order, and should be all anyone would need for the DIP switch settings. Make sure you are looking at the right settings for the right ROMs.

http://s202.photobucket.com/albums/aa154/UniversalRiot/?action=view&current=IMG_0001.jpg

http://s202.photobucket.com/albums/aa154/UniversalRiot/?action=view&current=IMG_0002.jpg

http://s202.photobucket.com/albums/aa154/UniversalRiot/?action=view&current=IMG_0003.jpg

http://s202.photobucket.com/albums/aa154/UniversalRiot/?action=view&current=IMG_0004.jpg

--Ryan
 
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Let me know if you need any other information. I also have an AT&T 6300 service manual.

--Ryan
 
Well here I am again looking for the same help. I have posted what I need in a different better to understand manner:
My AT&T 6300 had been running fine, until I sold my main PC. I put the AT&T in place of it. All was well for the first week. Then things went wrong, and I feared it's death was on the horizon. It's hard drive was auto-parking. When power is removed, it uses its last bit of juice to park the heads. It started parking them while in use, or while the system was idling. Once the floppy drive wouldn't read or write a disk. That only happened every few days. But then it started resetting. Sometimes to make it reset all it took was to bump the table or to just tap by the system unit. Other times I could bang things all over the table and have nothing happen. I reseated ALL socketed chips. I replaced the BIOS. I cursed at it multiple times to no avail. I then wondered if maybe its video was bad. I took the mobo of my other AT&T 6300 and hooked it into the proprietary video board, power supply, and drives. Everything worked fine. So what did that leave me with? A dead AT&T mobo and a good case. Anyone know what the problem might be? I can replace every socketed chip on the board EXCEPT the processor, which may be the problem. I would really rather not have to ship my AT&T from West Virginia down here, and thus would rather just fix the one I have.
I am going to work on replacing all the chips tonight, and see what I get. If it still doens't work, then I will work on it Sunday afternoon.

--Ryan
 
I don't really have enough knowledge or experience to comment with any authority but could there be intermittent power outages or flucuations within the motherboard itself. Have you had a good close look at the tracks to see if there are no obvious short-circuits etc?

Sounds like a thorny problem much like the ones I had with my System 80 drives a couple of weeks ago. Those drove me nuts! In the end, the symptoms were caused by a number of different faults. Hope you find the cause(s).
 
Ah, I forgot to mention something important. I have another AT&T 6300. Just so I could be sure it was a bad power supply in the dead machine, I grabbed the mobo out of my good AT&T, and put it in place of the bad mobo. I hooked it all up, inlcluding the drives. Much to my surprise, everything worked! So that left me with the knowledge that my power supply, drives, and video card in my bad AT&T was bad, and thus it was the mobo from it that was bad. So I took the good mobo back out and put it in it's original case, and connected the bad mobo back into it's case and peripherals. For good measure, I powered it on again, now that I knew I ahd a good connection there. Still nothing. I decided I will do the chip thing in just a little bit. I decided to go to bed last night instead!

--Ryan
 
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