PSA - more bad TL072s

Laundryroom David

Laundryroom David

Keyboard Cowboy 🤠
If you’re troubleshooting a build that involves TL072s, don’t assume the chips are good even if purchased from reputable sources. I built a @szukalski Blue Sheep yesterday that just would not work. I narrowed it down to the ICs. Popped in known good NE5532s and it sounds awesome. The TL072s I was using were either from Digikey or SBP, so it’s def not a dodgy seller. Anyway, carry on building something! Hopefully this note will help somebody’s sanity.

EDIT: I traced this tube of chips back to a Digikey order.
 
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MichaelW said:
How many bad ones did you have? I pulled out my Kliche Special Edition prototype today and it was acting weird. Like intermittent pseudo drop outs. I was thinking to check the 072's.
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This particular tube had 10 total ICs. Three went in a Promethium and 2 in the Blue Sheep. After I got the Blue Sheep going with NE5532s, I dug into my supplies and found some other old TL072s not from the tube of doom. The old ones work in the Blue Sheep.

Interestingly, the Promethium shat the bed last night - ie no go. I pulled the 3 TL072s from it (again from the Tube of Doom) and subbed in some 4558s I had handy. Came back to life. Dug around and found 3 more TL072s from the old supply, popped ‘em instead and voila. All good.

That’s 5 out of 10 bad and I have 3 left in the tube. I dunno which pedals happened to get the other 2 but assume they were ok because I haven’t had any other pedals fail like the Promethium and Blue Sheep did.

This is the first time I’ve ever experienced this kind of failure from a batch of ICs and I’m dumbfounded.
 
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Laundryroom David said:
If you’re troubleshooting a build that involves TL072s, don’t assume the chips are good even if purchased from reputable sources. I built a @szukalski Blue Sheep yesterday that just would not work. I narrowed it down to the ICs. Popped in known good NE5532s and it sounds awesome. The TL072s I was using were either from Digikey or SBP, so it’s def not a dodgy seller. Anyway, carry on building something! Hopefully this note will help somebody’s sanity.
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1692326625110.png
The one of the left is FAKE Texas Inst., No Dot, With ''D'' shape indent............................. Genuine Texas Instrument with Dot only!
Get some acetone and if the Print wipes of , it's definately a Fake
 
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Laundryroom David said:
This particular tube had 10 total ICs. Three went in a Promethium and 2 in the Blue Sheep. After I got the Blue Sheep going with NE5532s, I dug into my supplies and found some other old TL072s not from the tube of doom. The old ones work in the Blue Sheep.

Interestingly, the Promethium shat the bed last night - ie no go. I pulled the 3 TL072s from it (again from the Tube of Doom) and subbed in some 4558s I had handy. Came back to life. Dug around and found 3 more TL072s from the old supply, popped ‘em instead and voila. All good.

That’s 5 out of 10 bad and I have 3 left in the tube. I dunno which pedals happened to get the other 2 but assume they were ok because I haven’t had any other pedals fail like the Promethium and Blue Sheep did.

This is the first time I’ve ever experienced this kind of failure from a batch of ICs and I’m dumbfounded.
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That IS nuts....I buy all my IC's from StompBoxParts. And TL072's I usually get the "CP"s 20 at a time.
 
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Ironically I have a bag of no name fake Chinese NE5532's I got from Amazon when I first started building and didn't know any better. They look like hell but have all worked like a champ. They perform in circuits exactly the same as the real deal ones I have from SBP.
 
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