Need Help Testing LM741CN Op Amp Measurements?

[Steve Mavronis]

Not sure what happened with the 741 unless I gave it away.

I think you may have put it here:

   

^^^ LOL the one in my avatar is a Motorola 1987 for the year I was married. <3

Here are all the 741 DIP-8 chips I have:

[PRR]

> Uh oh

Like R.G., I bet "all" 741 sound the same in blind tasting.

I can see wanting a nice date-code just for historical reference. I often use those codes when guessing the age of old gear. Even new stuff: the PVC pipe I used to vent my new furnace was made 37 days before I bought it (fresh!!), and can be a reference for the poor slob who comes after me in 2035 and wonders how old that junker is.

Get a very teeny brush.

[Steve Mavronis]

Like R.G., I bet "all" 741 sound the same in blind tasting. I can see wanting a nice date-code just for historical reference.  

That's what I mean and totally agree on both points! My friend just wants it restored to historical 'reference' parts. If not it only changes the look a bit with a modern part replacement. It will sound just the same.

[armdnrdy]

My friend just wants it restored to historical 'reference' parts.

Depending on how good of a friend he is....

Do what the Chinese do to electronic components.

Sand off the original numbers and date code...and reprint whatever you want...and then tell your friend....
after a long, hard search, being the resourceful type that you are...you were able to find a replacement  741 from the exact year...and month! 

[Steve Mavronis]

My friend just wants it restored to historical 'reference' parts.

Do what the Chinese do to electronic components. Sand off the original numbers and date code...and reprint whatever you want...and then tell your friend....
after a long, hard search, being the resourceful type that you are...you were able to find a replacement  741 from the exact year...and month! 

Haha I actually mentioned that to him! China sells all kinds of 'nos' chips. I would never be sure if it were authentic. But I told him we could replace it with a modern 741 with the same pin 1 dots and have it marked with the same text as long as it would stay with him and not be resold as having original parts. To mark something up only for yourself is okay but not to counterfeit it away to make a buck.

[Steve Mavronis]

I did send you an RCA one actually, along with a vintage RCA3080 prior to that (checked my PMs) but it must have been lost in the post if you didn't get it.

Hi Scruffie, I'm curious only since you brought this up twice in this thread. I can't find any PM shows you actually sent me an RCA 741? I just went through all our messages about sending chips. You only sent me an RCA CA3080E silicon chip (around same time I sent you my 250 clone PCB) which I greatly appreciate and used it in my Dyna Comp clone. You kept mentioning the old 741's you had but you were also in the middle of a house move so it got a little confusing. No biggie because I'm done with my DIY clone project for years now and don't need it personally and they all do sound the same. But I didn't want a false impression here that I'm asking for something that I already got. So I will PM you now with the relevant messages you sent, in chronological order from oldest to newest dates. I didn't want to post this here although the topic is not really private now or needs to be. Doesn't matter but I guess you could have sent it at some point and it was just lost in international mail Twilight Zone!

[Steve Mavronis]

I was looking through a set of photos of DOD 250 gutshots from 1976-1981 (up to 1st yellows that features the same PCB as the greys) and here are just a few examples (some are suspect) with date codes. I'm wondering if I can get away with my Texas Instruments UA741CP Malaysia; they have a date code of 7xx which could mean 1977 or 1987 or 1997 for that matter:

1981 early yellow DOD 250 op amps:
- Texas Instruments UA741CP Malaysia (009)

1980 grey DOD 250 op amps:
- Texas Instruments UA741CP Malaysia (009)

1979 grey DOD 250 op amps:
- National Semiconductor LM741CN (810)
- National Semiconductor LM741CN (909)
- National Semiconductor LM741CN (913)
- RCA LM741CN (901)
- RCA LM741CN (832)
- Fairchild UA741 TCH(412) Korea (suspect?)

1978 grey DOD 250 op amps:
- Teledyne 741CP (7517)
- RCA LM741CN (832)
- National Semiconductor LM741CN (745)
- National Semiconductor LM741CN (807)
- National Semiconductor LM741CN (750)

1976 grey DOD 250 op amps:
- Signetics (Now Philips) UA741C (7610)

Unsorted unverified DOD 250 op amps:
- Motorola LM741CN (7922 or 7822)
- Fairchild LM741CN (139)
- Texas Instruments UA741CP (650)
- National Semiconductor LM741CN (743)

[Steve Mavronis]

Do you think this is a good 'compromise' chip?

http://i.ebayimg.com/00/s/MTYwMFgxMjAw/z/W4oAAOSw7ThUizEr/$_57.JPG

It's a Texas Instruments HB UA741CP with 914 date code down the side. The 0xx dated ones appeared on the final 1980 grey 250's. This one looks like 1979 same date label style. I haven't seen a 1979 PCB (pre-100 Ohm voltage resistor) with a UA741CP but this may be a decent compromise chip and maybe as close as he's going to get.

[EDIT] Anyway he bought them so that's going to be the deal to get this fixed. He's supposed to send me a 2nd grey 250 to refurbish so will send me the chip to use then. Looks like he's becoming a collector.