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Vaxstation 3100 - troubleshooting assistance please!

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dhoelzer

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Joined
Oct 20, 2012
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I'm trying to resuscitate a Vaxstation 3100 here. I'm actually not entirely certain which 3100 it is so I can't be more specific. However, there's clearly something wrong in the memory department. I've managed to get it joined to my cluster, but the memory available forces pretty much everything to be swapped out.

I'm looking at the VAXstation 3100 Maintenance Guide Addendum Models 38 & 48 which can be found online to try to sort this out but can't seem to reconcile what I'm seeing.

After running the self tests, test 50 (configuration status) reports the following... I'm trimming down to only items marked with question marks since those are indicating faults of some kind:

? CLK 0000.0005
? DZ 0000.4001
00000001 00000001 00000001 00004001 00000000 00000000
? MEM 0020.0081 <--- This is the one that I think actually matters.. next line too
00400000

As I read this, it's claiming on the MEM line to have 32 megs of RAM... but the next line seems to indicate only 4 megs of RAM. Additionally, the 0081 seems to indicate that there's an error (manual says anything other than 0001 is bad) but then there should be another 8 digit code next to the 00400000 to indicate where the issue is. CLK and DZ errors are not serious. CLK is obviously the clock. DZ is the serial line, which I'm using to talk to it so that can't be serious either. :)

The system exerciser doesn't shed any illumination. If it is to be believed (and if I'm reading it right) it seems that everything is just fine:

B 0010 MEM 0135.0001 1 00A0 0 00:04:16

The .0001 in the exerciser, again, supposedly indicates success while the 135 indicates pages tested.

Any thoughts for a next step or some assistance if I'm completely misreading these?

Thanks!
 
dhoelzer said:
It's a KA42-A V1.3
Click to expand...

OK, that should make it a VAXstation 3100 M30 or a VAXstation 3100 M40. It is always confusing with VAXstation 3100 or MicroVAX 3100 trying to figure out exactly which one you have, and then find the appropriate manuals.

I found a copy of the VAXstation 3100 Model 30 Owner's Manual, EK-265AA-OM-001 online, but not a copy of the VAXstation 3100 Maintenance Guide, EK-285AA-MG. Everything seems to be for the newer 3100 models.
 
From what I can find it definitely appears to be an issue with the memory. Apparently, the system board memory is fine. It's something on one of the stacked daughter boards. :(

I'm going to have to take it all apart tomorrow and hope that the 16 meg board is ok.. or that the 12 meg board is ok... It's going to be pretty tough to find a replacement 12 or 16 meg board for this thing.

Thanks!

gslick said:
OK, that should make it a VAXstation 3100 M30 or a VAXstation 3100 M40. It is always confusing with VAXstation 3100 or MicroVAX 3100 trying to figure out exactly which one you have, and then find the appropriate manuals.

I found a copy of the VAXstation 3100 Model 30 Owner's Manual, EK-265AA-OM-001 online, but not a copy of the VAXstation 3100 Maintenance Guide, EK-285AA-MG. Everything seems to be for the newer 3100 models.
Click to expand...
 
As a side note, VMS is incredibly slow with 4 megs of RAM.

dhoelzer said:
From what I can find it definitely appears to be an issue with the memory. Apparently, the system board memory is fine. It's something on one of the stacked daughter boards. :(

I'm going to have to take it all apart tomorrow and hope that the 16 meg board is ok.. or that the 12 meg board is ok... It's going to be pretty tough to find a replacement 12 or 16 meg board for this thing.

Thanks!
Click to expand...
 
I have an update. Hopefully there are some DEC hardware folks out there who can offer some advice.

I pulled the Vax all apart. The system continues to properly recognize the amount of RAM available whether I use the 12 meg board, the 16 meg board or the two boards stacked, but it also continues to throw an error and only use the 4 megs that are on board. This makes me think that the daughterboards are actually ok. That and a visual inspection of the main board.

In the corner of the board where the battery would typically connect it appears that a burst battery managed to wick acid up the wires to the connector. Looking at what's going on in this region of the board, it appears to be right next to the on board 4 megs. If someone can have a look at the attached photos, here are some questions I have:

1) Is this a multi layer board or just a two layer/top & bottom board?
2) Looking at the green stuff along the pins of these DIPs, does it seem possible that this could be causing the daughterboards to be ignored? (introducing parity errors, for example?)
3) If you know Vax hardware (I can't find a schematic for this) do these chips have anything to do with the memory subsystem?

Thanks!
IMG_0807.jpgIMG_0808.jpg
 
Hi All;
Dhoelzer, I have been Told, by others more experienced than me.. When I have worked on my Old 386 - 486 PC Boards that it can cause many problems, I have had Boards that I could clean up and they would Work Fine and Some that never worked again..
So, first I would Say Yes, Clean up the Affected Area, at worst it won't fix the Problem, at best it will fix the problem..
Also, check for continuity on all Traces where to have found the Battery chemical has spilled onto the Board, and make sure that they are connected and two that they are not shorted to anything else..Check everything in the affected area whether you see a spill or not or residue..
THANK YOU Marty
 
I assume those must be multi layer boards. I have a dead one from a 3100 M76. I'll have to take a look and see if there is are layer count masks on it somewhere.

The first thing I do with any MicroVAX / VAXstation I receive is remove the clock battery. Those nicad packs are evil. If they haven't died and started leaking yet they will soon and you'll end up with that nasty corrosion destroying things.
 
Just to wrap this up, I picked up another KA42 main board and it completely resolves the issues. Both daughterboards are recognized correctly.

Someday when I have some time I'll solder the suspicious battery damaged chips and see if I can repair the board to bring it back into service.

Thanks folks!
 
Good that you're back in service with a working motherboard. After removing the old nicad battery packs from mine I never bother reinstalling replacement batteries. I figure I would rather have to type in the date and time whenever I power them up again than have to worry about the batteries going bad and destroying things.
 
gslick said:
Good that you're back in service with a working motherboard. After removing the old nicad battery packs from mine I never bother reinstalling replacement batteries. I figure I would rather have to type in the date and time whenever I power them up again than have to worry about the batteries going bad and destroying things.
Click to expand...

Pretty much every microVAX base box has one hidden in it. First thing you should do when you get a new one is hunt it down and toss it. The bigger the box the harder it is to find and get out. The VAX 3400/4000/etc have the bastards in the I/O panel and you wont even know it's there until you see stuff melting. You usually have to take the IO panel apart to get the battery out too.
 
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