IBM chip cross reference list?

Mattis Lind mattislind at
Sat Mar 14 05:21:20 CDT 2020

I am helping a guy with a dead IBM 3279 terminal

The PSU does not seem to work. But as usual it is impossible to find any
schematic online for IBM stuff. Just interconnection diagram and high level

Now the PSU circuit seems to be quite simple with just one IC in it. A chip
marked 4216092.

>From the look of mold I guess that the manufacturer is Texas Instruments.
At least it matches very well with other TI chips manufactured in the same
time frame.

The rest is looking like a quite simple flyback mode PSU:  A transformer
with air gaps, no output filter inductors and one single power transistor.

Is there a cross reference list available for IBM numbers to standard chips?

It shouldn't be that hard to figure from the how it connected, though,
since it is most likely a standard chip. It can be a TL494 or SG3524


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