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Good or bad IC's - your experiences

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alank2

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I've been building an Altair 8800C and have been plagued with bad IC's. So far:

74LS74, 74LS02, and now 74LS244 all made by Fairchild in 1982 in either Indonesia or Singapore.

Are there known brands/year ranges/manufacture locations that are terrible and didn't hold up over time vs. other ones that were reliable and solid?
 
The 74LS244 must be mis-marked - maybe it is a 74LS240. It inverts when it shouldn't!
 
Are you purchasing these ICs from sources like eBay, Amazon, or China? There are many Youtube videos showing chips purchased at these locations either being fake, remarked, or just plain dead because of torture methods used to remove them from boards.
 
I ordered these from Unicorn Electronics. Tested all of them that aren't plugged into boards yet and found another defective 74LS74. I ordered all TI replacements from Mouser today so as soon as they arrive, they are going in and the ones coming out will also be tested.
 
The Fairchild 74xx74s were often not having enough pullup current. When I was involved, we stopped using them, because the way they tested them, they thought there was no issue with them.
Dwight
 
Chuck(G) said:
There shouldn't be a problem purchasing new, not re-used chips in this family.
Click to expand...

Correct, but from trusted sources like mouser, jameco, digikey, newark, etc.. I wouldn't even trust "new" purchases from the three other sources I mentioned.
 
I've purchased stuff from Europe for obsolete, no-longer-made parts, particularly Hungarian Tungsram/MEV, which pretty much copied the Fairchild line of the 1970s-80s. The factory burned down in the 1980s and was never rebuilt, so the stock you see will be pre-1990. There's a ton of the military surplus stuff out there; it's of pretty good quality.
 
alank2 said:
I've been building an Altair 8800C and have been plagued with bad IC's. So far:

74LS74, 74LS02, and now 74LS244 all made by Fairchild in 1982 in either Indonesia or Singapore.

Are there known brands/year ranges/manufacture locations that are terrible and didn't hold up over time vs. other ones that were reliable and solid?
Click to expand...
Who knows how these chips were handled over the last 40 years. Just because a chip is "new" (which no one can really assure you anyway), doesn't mean it must still work. Semiconductor do age, even when not in use. Also, they may have ESD damage from improper handling/storage. I don't even see the reason for buying such old chips when you can still get new ones made recently.
 
Jameco: Overall, I've had good luck with them, but I bought some chips that were claimed to be 68B09E. They were sold as "refurbished" and labeled as 68B09E, but they turned out to be 68(B)09 - not sure about the B because I only ran them at 1MHz...

To the original question: I worked with someone in the mid-80s who had previously done hardware design. He used to specify "any vendor but National" for some parts (I think it was '74 flip flops, but don't remember for sure, and I don't recall what particular problems he had seen with them...)
 
DutchMaker said:
I've done several builds with 74LS/HCT series chips and never encountered one the didn't work.
All were purchased from Chinese sellers.
I think you're just very unlucky (or maybe I have been very lucky) :D
Click to expand...

I'm up to 2 74LS74's that failed, one 74LS02 that failed, and one mi-smarked 74LS244 that behaves and tests good as a 74LS240. All Fairchild, 1982, labeled "PC" after the part number.
 
I would like warn about soldering any logic ic before testing on tester.
Usually Aliexpress is a cheap way of them but for example my recently purchased LS374 were failed (10/10) from one seller. I ordered twice and the second lot was also defective.
So good practice is testing chips after arriving.
 
You're just asking for head aches ordering anything from AliExpress.
 
It's true that you must test new to you IC's or it can bite you in the butt. I recovered hundreds of 74 (plain - not LS etc) TTL series IC's from surplus boards years ago. Back when I had far less $'s and TTL IC's cost a lot more than today. Most are '70's and '80's vintage and have been stored for decades and moved cross country a few times. Recently I ran all of those that I have left through my small Chinese component and IC tester and also my TL866 and deep 6'ed any that failed. I was surprised that that was well less than 10% of them. Maybe 10 years ago I purchased a large Akro Mills storage bin full of a few hundred 74LS IC's from an estate sale and 99+% of them were new and ECG branded. Very few problems with them. I've also purchased IC's from Jameco, Unicorn, Mouser and a few other sources and always test them as they come in. I even have a few blister pack IC's purchased from Radio Shack and Jameco (Jim Pak) that have to be 30 years old. The surplus sellers always seem to have more failures than the main stream electronics companies. The Chinese sellers vary from very good to near useless and unless you are lucky seem to come and go and so are a crap shoot as to what you will get. Expect relabeled parts at best. Rare LSI parts can be a pure crap shoot and getting working examples of what you expect is unexpected in most cases.
 
I discovered that my EEPROM programmer (Minipro TL866) can also test logic IC's, most of the ones I had anyway. What can't the TL866 do? Everyone should have one.
 
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