[vcf-midatlantic] cranky 5150 - PART 2

[Steven Michelsen]

Uh oh.  After writing the post below I read the appropriate minuszerodegrees
page, that suggested among other things, "Faulty motherboard - bad solder
joint on keyboard connector".  So I took a look - here's what I found.  Not
promising.  But fixable!  Does this look like the culprit?  But what about
the memory errors?

 

https://www.youtube.com/watch?v=3A9uULoyJgk

 

 

 

From: Steven Michelsen [mailto:stevenm at optonline.net] 
Sent: Saturday, November 05, 2016 4:55 PM
To: 'vcf-midatlantic' <vcf-midatlantic at lists.vintagecomputerfederation.org>
Subject: cranky 5150

 

I thought for once I could get a new IBM 5150 and NOT have to come crawling
to the group for advice, but noooo..

 

Just got an ebay 5150.  I couldn't resist - it was relatively local, and
included a 5151 monitor (but no keyboard), for a decent price.  I have a
keyboard, so no worries.  Took the top off to peek inside to confirm
everything was seated, etc.  I started it (with the top off) and got a
keyboard error (301).  I discovered that my keyboard was set on AT instead
of XT.  Flipped that switch and viola, the 5150 booted with a Dos 2.11 disk.
Poked around the disk, ran a Basic file that happened to be on it, tested
the "B" drive, formatted a disk - it's all good.  I even booted a few times
with no issue.

 

I put the lid back on and started it again.  This time I get this.

 

40FF

 

. and the PC is beeping away, long beeps that do not stop!

 

I restart again and get this.

 

40FF

201 301

 

This time there's no beeping, it just displays the msg.  The disk drive was
read from briefly, then nothing.

 

I pull out what appears to be a memory expansion card.  Here
<https://dl.dropboxusercontent.com/u/65762317/forums/IBM_5150_RAM_board.jpg>
's a picture of it.  I started it without the card and get this.

 

40D0

 

I took another look at that RAM card and found THIS on the back
<https://dl.dropboxusercontent.com/u/65762317/forums/5150_bug.jpg> !  My PC
had a bug.  Anyway, cleaning that up didn't help.  I replaced the card,
started it and got yet another, different 40xx error.

 

OK, where do I go from here?  The darn thing worked at one point today; why
not all the time?  I have looked for unseated chips, cards and cables, as
least as far as I could without pulling a floppy drive, and found that
everything is secure.

 

Thanks as always,

Steve