/diy/ - Do It Yourself » Thread #894908

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Anonymous Thu 29 Oct 2015 00:24:15 No.894908 View Reply Report Delete

Quoted By: >>894910

I don't know much about circuitry and I'm looking to replace some ICs/op amps in a 1979 reel to reel. I've posted about this before but I'm still confused about it.

So here is the layout of what is called the analog torque board. IC 29 is labeled as "7402" in the schematic. The IC that is actually in the reel to reel is labeled "sn7402N". If I want to replace that IC, do I need to find the exact same one, or do I just need one with 7402 in the name?

Another example is one in the schematic that is labeled "081". If the one that is actually there says "TL081CP", would I be able to replace that one with a "TL081GP"?

The reel to reel is pretty old and many of the parts are obsolete, so finding the exact part is pretty difficult. Is it unnecessary to be that exact about it?

Anonymous

Anonymous Thu 29 Oct 2015 00:25:17 No.894909 Report Delete

Quoted By:

Also, is mouser.com a reliable site for buying these op amps?

Anonymous

Anonymous Thu 29 Oct 2015 00:43:53 No.894910 Report Delete

Quoted By: >>894916

>>894908
>or do I just need one with 7402 in the name?

read
https://en.wikipedia.org/wiki/7400_series#7400_series_derivative_families

basically keep the letters in the middle the same

if it says 7402 then any ***7402*** will do.

>cp/gp
uhhh probably? where is that on the picture though

>mouser
depends where you live, americans use it all the time

Anonymous

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Anonymous Thu 29 Oct 2015 00:56:24 No.894916 Report Delete

Quoted By: >>894923

>>894910
>basically keep the letters in the middle the same
Cool. Are you saying that just for the 7400 series based on what you read in that article, or is it going to be basically the same for most of the ICs?

>uhhh probably? where is that on the picture though
That one actually isn't on there, it's on another board which I don't have the schematic for with me right now.

Anonymous

Anonymous Thu 29 Oct 2015 01:15:02 No.894923 Report Delete

Quoted By:

>>894916
yeah thats how the 7400 series works, there is the 4000 series but thats much easier there aren't variations.
pretty much everything else is either a universal part like e.g. 5v regulator 7805, you get the letters before the number vary to tell you the manufacturer.
other times its one manufacturer makes a part and nobody else makes it, like maxim makes max232, i don't think anyone else makes them but you get chinese copies pretending to be maxim chips.

the letters after the number can be anything really you have to read the datasheet for the chip but usually there is a letter in there somewhere at the end that tells you the package, if its dip or surface mount or whatever.

typically you just google it and check the datasheet, you do it enough and you will be thinking of them while you sleep.

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