TL074L replacement

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Midnightsun

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Aug 12, 2009
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The PCB boards from my early Lexicon 224XL are fully populated with spring contact sockets. Many of them have failed by loosing tension and therefore proper contact with the IC legs. That caused an error code party in the Larc. It's a known issue with the early 224X[L] production runs. Fixable but time consuming. I'm using gold plated turned pin /"tulip" IC sockets in exchange. I agree they can be a bit tight. Means, sometimes it can be a bit tricky when setting the ICs back in the sockets without bending a leg. I have the impression that some IC legs might be more "soft" or thin than others and bend more easily when pushed in the new socket. It helps to press the chip in with thumb and first finger on the sides/on the legs from the IC to guide and to stabilise the procedure a bit better
 

FIX

Paul Wolff
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May 5, 2021
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If you have shit sockets, just solder good ones into the old ones so you don’t take the chance of pulling out the feed through on a multi layer board.

The L can mean a package difference, like height or location, etc. depends on the manufacturer.

In this case, it means lead free
 
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tgs

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If you have shit sockets, justnsilder good ones into the old ones so you don’t take the chance of pulling out the feed through on a multi layer board.

The L can mean a package difference, like height or location, etc. depends on the manufacturer.

In this case, it means lead free
Good to know, thanks fix!
 

abbey road d enfer

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The PCB boards from my early Lexicon 224XL are fully populated with spring contact sockets. Many of them have failed by loosing tension and therefore proper contact with the IC legs.
I have seen IC sockets giving improper contact: it was associated with tarnishing of the contacts, resulting from chemical contamination. In most cases, reseating the IC fixed the problem.
I have never noticed them loosing tension significantly.
 

Midnightsun

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I have seen IC sockets giving improper contact: it was associated with tarnishing of the contacts, resulting from chemical contamination. In most cases, reseating the IC fixed the problem.
I have never noticed them loosing tension significantly.
My usual experience as well. I'm thinking improper contact is based on a light oxidation layer that had built up over time on the contacts. Based on that I had components rather stuck in a socket than falling out. Usually I'm unnecessarily overdoing it as follows: Giving the empty oxidised sockets a spray with Kontakt 60 [pretty agressive, it can loosen rusty screws & stuck components in sockets] a careful massage with an old toothbrush and a final wash with Kontakt WL. Component legs if tarnished are getting a few downstrokes with 0000 steel wool to get them back to shiny.
The tensionless sockets in my old lexicon are the only exception. A few pads on the back of the PCB let some of the ICs come out.
 

Newmarket

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Be aware that not all sockets of a particular permutation type - spring leaf / turned pin / "tulip" are equal.
In terms of preference, much depends on envisaged use. eg are you using sockets so that you can test with various op-amp types - so ics will be in/out of the socket quite a lot - ? Or is it for the case of a component failure so you can substitute without disassembly / desoldering etc. depending on the product specifics. In which case it the ic may never be removed , or removed/inserted only a few times over the product life.
Personally I veer toward turned pin types although they can work out a lot more expensive. But spring leaf types from a reputable manufacturer don't really worry me.

On an associated note I'm probably going to annoy quite a few here by saying that you need to get SMT skills up to scratch. At least to SO8 / SOT-23 level. OTOH SMT to TH adaptors are your friend :)
Not ideal electrically but not usually a problem for "DIY".
 

ccaudle

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I didn't know you could buy modern ICs that are not lead free....

Unisonic Technologies (UTC) is the only vendor datasheet I have found with TL074L. Possibly the OP had a UTC device, or had a device from 25 years ago when vendors still made a distinction between their tin/lead plated parts and pure tin plated parts. I don't think I've seen a device in at least 20 years that didn't have pure tin plated leads, unless it was a specialty part still being manufactured for defense/telco/medical applications which got a pass on going lead free.
 

tgs

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May 30, 2013
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Just a little update on this: got a couple of new TL074s from Volker (thank you!), got the faulty one off nice and clean and put in the new one, all good and working now. I ordered a bunch of sockets so I have them in stock but I couldn't fit it on this module since the IC is underneath the DI input with a couple of caps sticking out. Lower profile caps or sockets might have done the trick, it's really right on the limit.
 
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