• Please review our updated Terms and Rules here
  • Exhibitor application for VCF West 2022 is now open! If you are interested in exhibiting, please fill out the form here.
  • Here are the results of the VCF East 2022 Post Event Survey: Survey Results

How to test 2102 RAM Chips?

atod

Experienced Member
Joined
Oct 14, 2010
Messages
303
Location
New York, NY
Hi Folks,

I'm bringing up an ADM-3A (which I just repaired the keyboard to) and it appears it has bad RAM. This is the upper-lower case version with 14 2102 RAMs in two banks of 8. I believe each bank reflects the odd and even lines.

Does anyone know how to test this RAM either in board or out of board? I have a LA and scope. I guess I could just look for ASCII patterns ending up in ram upon key press, however I wonder if it would be easier to place in some sort of RAM tester. I would replace all the RAMs, but they are $3/ea and that's like $42 in RAM.

Also, does anyone know if there is a "drop in" faster replacement for 2102 RAM?

Thanks
 

MikeS

Veteran Member
Joined
Dec 23, 2005
Messages
7,478
Location
Toronto ON Canada
Hi Folks,

I'm bringing up an ADM-3A (which I just repaired the keyboard to) and it appears it has bad RAM. This is the upper-lower case version with 14 2102 RAMs in two banks of 8. I believe each bank reflects the odd and even lines.
Well, your problem's obvious: you're missing two chips! ;-)

Why faster RAM? Planning to overclock that ADM-3A?

You could try removing them all and go through them inserting one pair at a time in a given pair of sockets, looking for a display pattern that's different from the rest; not foolproof by any means, but you might get lucky.
 
Last edited:

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
38,870
Location
Pacific Northwest, USA
There are more variations on the 2102 than you can shake a stick at (and I include the 9102 as well).

There are low-power versions (2102L), various speeds (-1, -2, -3) and combinations 2102LH (low power/high speed) and ones with power-down mode (21L02).

Fastest speed seems to be 250nsec. But the low=power versions do generate a lot less heat than do the standard versions.
 

atod

Experienced Member
Joined
Oct 14, 2010
Messages
303
Location
New York, NY
Well, your problem's obvious: you're missing two chips! ;-)

Why faster RAM? Planning to overclock that ADM-3A?

You could try removing them all and go through them inserting one pair at a time in a given pair of sockets, looking for a display pattern that's different from the rest; not foolproof by any means, but you might get lucky.

They are not socketed. It's probably worth the effort of me pulling the ICs and replacing them with sockets.
 
Top