Which company is MFR90073? (Manufacturer of TTL chips in 1981)...

Somehow the link got lost, sorry - here it is:

Erik:

The numbers look private.

On Sat, 07 Jun 2008 21:43:09 +0200, Erik Baigar put finger to keyboard and composed:

I can't help, but ISTR that Beckman and Allen Bradley made resistor arrays at around that time. In any case, wouldn't it be relatively easy to confirm with a multimeter whether your parts were in fact resistors?

- Franc Zabkar

Also, the packages look very similar to late 70s Beckman hybrid packages. Their DACs had the same white dot and black ceramic package, but not identical. Mark

Some of thses 67PSxxxxx are resistor networks.

The oscillator NSN below is also of the same 67PS series, so the part numbers probably correspond to the parts list for the 67PS contract.

The following is from iso-parts search for "67PS" View NSN Details 4310-00-479-2918 RING,PISTON View NSN Details 5815-99-649-2607 RING,CODING DISK View NSN Details 5841-99-659-8786 OSCILLATOR,RADIO FR View NSN Details 5845-99-653-3271 DELAY LINE View NSN Details 5845-99-653-4893 OSCILLATOR,RADIO FR View NSN Details 5905-99-658-8979 RESISTOR NETWORK,FI View NSN Details 5905-99-658-8980 RESISTOR NETWORK,FI View NSN Details 5905-99-658-8988 RESISTOR NETWORK,FI View NSN Details 5905-99-658-8990 RESISTOR NETWORK,FI View NSN Details 5905-99-658-8991 RESISTOR NETWORK,FI

Parts games are so much fun, Hope this helps you, Mark

Thanks for this hint. I wrote an email to them (custom chips dept) but did not get an answer so far. Let's give them some more time...

Yes I knew the webflis search before and tried the part numbers there. This black one 339-446 is used in a core memory driver near to the transistors driving the hinhibit lines. So I'd guess these beeing either transistor arrays, diode arrays or resistor arrays. Using a multimeter and doing some measurements makes the rersistors quite unlikely.

Erik.

Thans Franc for this hint. I unmonted the PCBs and tried with a digital multimeter. The 214-017 indeed is a resistor array containing 12 resistors with 2.2k each. The pin common to all resistors is No 14. In the application this is connected to +5V and the resistors are used for pulling up the open collector driven data lines of the 12 bit machine. There is no resistor present at pin 7. So for this one the puzzle is solved.

The 214-018 is a resistor array, too. It contains 8 resistors with 300R each. Two of them are used on the two PCBs holding the registers of the unit. They seem to be the pull up resistors for the internal data bus (only 6 resistors are used per array since each PCB contains 6 bits of the 12 bit length registers). There are the common pins for the resistors (2,5,9 and 12) which are all connected to +5V and the resistors are accessible at pins 1,3,4,6,8,10,11 and 13. Of course I am not able to figure out which of the common pins is connected to which resistor without desoldering the chip. But anyhow - this is not important.

The similar looking 214-020 is difficult to measure since the surrounding circuitry influences the results (I have three instances of this on in the unit and results differ). If it is a resistor array, the resistance must be higher than in the 214-017...

Thanks again,

best regards,

Erik.

Thanks Mark - of course this helps. It is always interesting to learn about new search engines and exchange thoughts!

Are you sure that EVERY part the military used, shows up there? I am quite sure, that the unit on my table is of some military origin

Thanks again,

Erik.

On Thu, 12 Jun 2008 06:27:49 +0200, Erik Baigar put finger to keyboard and composed:

FWIW, Sprague was manufacturing TND series diode arrays at around that time:

I have a FSA2719M DIP-16 diode array made by Fairchild in 1981:

It is equivalent to a TND3600 (manufacturer uncertain, possibly Sprague, logo is a "2" or "Z" in a circle).

I see Google references to resistor arrays made by Fairchild, including the RA08 in this 1979 patent:

I also have some DIP RC arrays from around that time.

BTW, none of my parts have the "blob" at pin 1.

- Franc Zabkar

...still no hint from CMC apart from the statement, that these have been made for what is now BAE in Rochester, but since the unit has been retired a decade ago, I doubt that there will be any information...

Franc Zabkar wrote:

Thanks for these interesting links. I am now quite sure (by measurements and drawing a little schematic), that the 339-446 is some RCD network. It is used to connect the open collector output of a buffer to the pulled up basis of a driver transistor for the core memories inhibit lines. Unfortunately it is not a simple diode array because measurements show the diode in the wrong direction. Maybe it contains Zehner diodes with a capacitor in parallel. The pinout is as follows:

So it might well be, that between 3 and 14 there is the Zehner diode and between 4 and 13 the capacitor and so on...

The second remaining unknown is the 214/020. Here I still have no guess.

Maybe the "blob" is not by the manufacturer but has been applied later by some sort of incoming inspection? At least they have been applied before the PCBs have been covered by the protective coating which makes it fun doing measurements on the PCBs...

Thanks again,

Erik.

Did more measurements on this one and investigated the circuitry around these chips. Now it is quite obvious: The 214-020 is a input frontend containing 5 diodes and 5 pull-down resistors.

I put a summary on all these custom chips on my web page at:

On the 214-020, the common pin is connected to ground and the resistors act as pull-downs. The input signals of the unit are applied to the diodes which shift the level 0.7V towards ground and the unit is listening to the junction between diode and resistor. Thus the combination increases noise resistance of the inputs and acts as pull-down...

Thanks for all comments...

Best regards,

Erik.