Help identifying vintage resistor network IC

Thread Starter

popcalent

Joined Mar 17, 2018
32
Hi,

I have these old Beckman resitor network 16-pin ICs that I salvaged from an old computer. I have many of these two varieties:

beckman.jpg

Pins 2, 3, 4, 5, 6, 7, and 8 are connected on both ICs. I ran my tester on different pins and I'm getting values of around 330 ohm on the one on the left (1898-37-0 7637), and random values (450 ohm, 890 ohm, etc.) on the one on the right (1898-39-0 7635). I don't know the pinout, I couldn't find it on the internet, so I don't know what I'm measuring. Does anyone know what these are and what the pinout is? Thanks!
 

AnalogKid

Joined Aug 1, 2013
9,043
What kind of computer? Also, where inside the computer were these parts located? Backplane? Processor board?

They could be custom parts with 2 or 3 resistors per external circuit pin, such as a 330/470 ohm termination network for a backplane data bus. If so, the common pins will be at the corners.

ak
 

Thread Starter

popcalent

Joined Mar 17, 2018
32
What kind of computer? Also, where inside the computer were these parts located? Backplane? Processor board?

They could be custom parts with 2 or 3 resistors per external circuit pin, such as a 330/470 ohm termination network for a backplane data bus. If so, the common pins will be at the corners.

ak
It was a really old computer. The kind that takes up the size of an entire wardrobe. It was exposed in my campus library, but people used it as a garbage disposal. I asked if I could pick some parts before it ended up being thrown away because people kept vandalising it and it was in very poor condition. I salvaged many ICs that I have identified, mainly 74XX ICs, and these resistor ICs. I can't tell what part of the computer it was because it had many boards that I couldn't identify at the time.
 

MisterBill2

Joined Jan 23, 2018
8,214
Mostly such resistor nnetwork modules were either reistors straight across, like pin 1 to pin 16, pin 2 to pin 15, or a lot of resistors with one common pin, usually on a corner, often pin 1 or 16. Those types can be quite useful even now. But they might also be terminator resistors, as already mentioned. Those have much fewer applications with current technology.
Some of those packages with the ceramic coating have the conductor pattern slightly visible it you look closely at the ceramic coating on top from an angle, with reflected light. If the top surface is not completely flat you may be able to discern a pattern beneath.
If all else fails, a resistance measurement between the various pins can provide the information that you seek. Tedious but not difficult.
 

MrChips

Joined Oct 2, 2009
23,073
There are many ways to manufacture a resistor network in a 16-pin DIP package.
I would suggest that you use an Ohmmeter to try and determine the arrangement.

I am going to guess that this is a custom array made by Beckman for a specific client.
Here are some clues.
7635 and 7637 are year and week codes.
1898 appears to identify 16-pin DIP package.
MSC 609-1 and MSC 610-2 could be the customer ID code.

Resistor network.jpg
Reference: http://www.interfacebus.com/resistor-network-styles.html


BI technologies resistor network.jpg
 

dl324

Joined Mar 30, 2015
12,678
Here's another:
clipimage.jpg

The part numbers don't conform to the usual markings for Beckman, so they could be custom and/or house marked devices.
 
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