OP-AMP Long-Term Reliability

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Gentlemen,

How reliable are the old 'tin-can' encapsulated op-amps from say 40
years ago? I'm talking about the ones that look like large transistors
and have typically 8 leads in the TO5-8 package. I'm unable to provide
a part number as these don't have one as such. Could be a 741 perhaps
but I can't be certain. Are they known to fail?

thanks.
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Re: OP-AMP Long-Term Reliability
On 2020/01/18 1:11 p.m., Cursitor Doom wrote:
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Many solid state devices from that era are still running. Physical  
damage (moisture working in via the leads) is one primary cause of  
failure. If the leads look good then chances are fairly good the device  
will work.

I use lots of 30 to 40+ year old components all the time for servicing  
our classic arcade games. Most are perfectly good. Other than  
electrolytic capacitors...they definitely have a shelf life/best before  
date!

John :-#)#

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Re: OP-AMP Long-Term Reliability
wrote:

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No sign of corrosion at all on the leads.

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So do I. The question wasn't about NOS components, but components that
have been in service for decades.


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Re: OP-AMP Long-Term Reliability
On 2020/01/18 5:26 p.m., Cursitor Doom wrote:
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My first sentence in my first paragraph was my (getting tired of 'my')  
experience about original esolid state devices still running.

Do please read what is written, I'm the only one here who is allowed to  
make the mistake of not reading entire posts before responding!

John ;-#)#

Re: OP-AMP Long-Term Reliability
On Saturday, 18 January 2020 21:11:24 UTC, Cursitor Doom  wrote:
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The problem components from that era are lytics of course and glob-top transistors.


NT

Re: OP-AMP Long-Term Reliability
On Sat, 18 Jan 2020 15:02:31 -0800 (PST), snipped-for-privacy@gmail.com wrote:

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OK, I have to know.. "Glob-top"??
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Re: OP-AMP Long-Term Reliability
On Sunday, 19 January 2020 01:23:38 UTC, Cursitor Doom  wrote:
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http://www.ichom.org/Overig-499982/Connectoren-schakelaars-kabels-FAIRCHILD-Glob-Top/

The round top is an epoxy glob covering the die, which sits on the flat thick sheet material that holds the leads. 2 tone ones make this easy to see, all black ones not so much.


NT

Re: OP-AMP Long-Term Reliability
On Sat, 18 Jan 2020 19:35:36 -0800 (PST), snipped-for-privacy@gmail.com wrote:


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Ah. Ok. I have a few hundred of those but some obscure part numbers
and all PNP so are unlikely to be called into service here. :)
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Re: OP-AMP Long-Term Reliability
On Sun, 19 Jan 2020 10:10:50 +0000, Cursitor Doom

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Those bring back not so fond memories.  The black potting epoxy was
optically transparent to infrared light.  I had a hell of a time
dealing with weird problems in the 1960's until I found the light
sensitivity problem with those transistors.  It took about a year for
Fairchild to clear their inventory and screw their unsuspecting
customers by continuing to sell these devices.  Eventually, they
changed over to the "PN" (TO-92) style package, which initially was
made from silicon epoxy instead of epoxy-B.  Silicon epoxy shrinks
slightly at high temperatures, causing the corrosive fluxes from the
wave soldering equipment to creep up the transistor leads by capillary
action, and corrode the leads and chip.  We had to x-ray the dead
parts to determine the failure mode and guess the cause.  It usually
took about a month for the transistors to rot to death.  I had a
difficult time getting Fairchild to understand that having *ALL* the
transistors on a PCB fail almost simultaneously after only a month was
sufficient grounds for suspecting that something might be wrong with
the parts.  They eventually switched to epoxy-B, but only after again
unloading their defective inventory on unsuspecting customers.  There
was also a problem with the UA2136 IF amp/detector IC, where chips
made in different Fairchild factories produced radically different
performance and stability.  I took great pride in personally removing
Fairchild from the approved vendor/manufacturers list, and finding
alternate sources for about $2.5 million/year of their components.
When I mentioned this to the sales rep, he acted like he didn't care
or it wasn't important.

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Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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