mystery OP-AMP

[Teach]

     I'm repairing a dead Tektronix FG501 Function Generator. sn B060534
     Turns out ALL thirteen OP-AMPs were non functional.

     I replaced all with 741's and It is working nicely that was easy.

     Now my question -----The "op-amps" in the unit were marked   (Old National Semiconductor LOGO) followed by 241....at the top.
                                                                                                         SL in the middle of the chip.
                                                                                                         60466 at the bottom.
                                                                                                         Large letters FVFVFV printed on the underside.
    That's right, 241 ! not 741....
   
    I searched for days.....
     
    What could this be ?   Fakes installed by previous repair attempt?  A part so obsolete it dis-appeared from the internet ?!!

    Anyone that can help Identify it.  Thank You !!!

[magic]

Prolly a custom Tek part number, see if you can find service manual.

LM341 was a three terminal voltage regulator, LM241 would have been an industrial temperature version of that. Surely none of that.

Teardown of the carcasses would reveal what they were.

[Teach]

    Magic, go to the head of the class-------------- You are CORRECT !!!

    I do have the manual, and it does indicate a Tek manufacture part number................ 156-0067-06

    Well DANG searched it up and It is indeed  a 741.

    Figured that by looking at the Pin-Out in the schematic.

    Mystery solved.
    Unit running smooth !!!

     Thank You Magic  !!!                      (P.S.  all the 741's in my Tek power supply were dead too(working fine now also))


     OLD OP-AMPS  Hmmmm.

[fzabkar]

You can often find an equivalent to the manufacturer's number at NTE Inc:

https://www.nteinc.com/search.php
http://www.nteinc.com/specs/900to999/pdf/nte941m.pdf

You can find old databooks here:

https://mirrorservice.org/sites/www.bitsavers.org/components/national/_dataBooks/

[David Hess]

The 156-0067-06 was selected for a +/-20 Volt supply voltage.  Originally these were all suppose to be from Motorola, RCA, or Texas Instruments so I wonder if they were replaced at some point.  Or maybe Tektronix got National to grade them for +/-20 volt operation and that is why the part number is weird.

They should be replaced with 44 volt parts like the 741, 741A, or 741M but *not* the commercial 741C which is only a 36 volt part.