[sdiy] Silver series TL074/84 op amps

philgallo philgallo at gmail.com
Sun Mar 20 00:03:43 CET 2016


Back in the day (turn of the decade 70's to 80's) we believed (with no evidence) that TI was overcompensating for a pin plating issue that back then was referred to as the 'TI Effect'.

TI made a process change and folks found their chip leads were turning black and had a corroded look. (Alarming in environmentally controlled installations)

Quickly TI parts were removed from BOMs and AVLs.

To their credit they quickly fixed the issued, allowed returns, many of the new parts started showing up with a top stripe of silver paint.  

It did announce that these parts were 'new' although I never read or was told this was the purpose.

p


> On Mar 19, 2016, at 3:08 PM, rsdio at audiobanshee.com wrote:
> 
> Over the years, I've seen countless authentic, unadulterated, functional pieces of audio gear with DIP chips that are silver instead of black. I believe that the only way you're going to get to the bottom of this is to collect date codes and manufacturers from authentic chips and then seek out the vintage data sheets for those chips. There should be some official documentation of the chip markings, including the color.
> 
> That said, the photo of those dodgy chips doesn't look like what I remember. The color is off, but that could be the quality of the photo, my memory, or the fact that they are dodgy.
> 
> If anyone finds a specific manufacturer, part number, and date code (one that isn't suspect of being counterfeit), please share it here. I have a number of vintage data books, so I could look up some of these if I happen to have the right years. I'm only focused on the date codes because I don't relish the idea of searching all data books for clues - at least the date codes should narrow down the search. So far, it seems like multiple op-amp and transconductance amp part numbers from various manufacturers have been made with this silver backing. Seems like we have to be able to find documentation on at least one of them.
> 
> Brian Willoughby
> Sound Consulting
> 
> 
>> On Mar 19, 2016, at 12:27 PM, "Tim Stinchcombe" <tim102 at timstinchcombe.co.uk> wrote:
>>    I'm hoping someone here can shed some light on what the 'special
>> purpose' of the silver-painted TI op amps were, which I've seen on several
>> occasions. The chips are clearly painted with silver paint and re-marked,
>> which in today's times of blacktopped counterfeit ICs looks very suspicious,
>> but back then (and I'm not sure when 'then' was either!) must have been seen
>> as acceptable. I'm presuming this was some sort of post-encapsulation
>> sorting for some parameter or other, thus giving a 'premium' chip?
>> 
>> There is a photo posted on the 'dodgy chips' thread at MuffWiggler:
>> 
>> https://www.muffwiggler.com/forum/viewtopic.php?p=2179517#2179517
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy



More information about the Synth-diy mailing list