Do these TL075CN s look real ??
- Thread starter gar381
- Start date
Help Support GroupDIY Audio Forum:
It could be real. I recall talk on diyaudio (I can't find it now) that TI used to paint the tops of their chips silver just to look different or something, and I vaguely remember seeing that myself decades ago.
Here's another example (again, not fake or real either way that I know of, but "could be real" just based on color of the top):
http://www.ebay.com/itm/LM301AP-DIP-8-LM301-Operational-Amplifiers-Texas-Instruments-/112426836155?hash=item1a2d2960bb:g:BJ8AAOSwnQhXpFLo
Here's another example (again, not fake or real either way that I know of, but "could be real" just based on color of the top):
http://www.ebay.com/itm/LM301AP-DIP-8-LM301-Operational-Amplifiers-Texas-Instruments-/112426836155?hash=item1a2d2960bb:g:BJ8AAOSwnQhXpFLo
clintrubber
Well-known member
I sure recall seeing TL074-types with silver tops as well.
When using these for Fender-style guitar amp circuits, be sure to convert them back to black tops...
When using these for Fender-style guitar amp circuits, be sure to convert them back to black tops...
IIRC Trident had silver TL072 which were selected to work at higher rail voltages in the Series 80 boards.
pucho812
Well-known member
mjrippe said:
Yes.... they were doing a +/-20VDC back in the day.... But we usually just dropped it down to +/-18VDC to make it easier to fix
How do they work?
JR
JR
pucho812 said:
20V? musta been a TSM, huh?
never had a problem with that voltage and those chips...
however, when the regulator failed in the power supply, and they got nearly +/- 40V we lost a few :-\
sorry to go off topic...back to the OP
i've seen a lot of silver 5534s from the 70s.
they look great on black circiut boards
How do those parts work? i.e. test them....
Back in the '70s when I would buy 1,000 TL074s at a time direct from TI. I would test them 100% and cull out low-mid single digits as rejects, so <1%. I would run a sine wave through all 4 amplifiers in series at high noise gain, but only unity signal gain.. the handful of bad op amps would show up as unusually noisy or distorted.
Since those are long obsolete and were manufactured some time ago, I would test them 100% before ASSuming they all work OK.
JR
Back in the '70s when I would buy 1,000 TL074s at a time direct from TI. I would test them 100% and cull out low-mid single digits as rejects, so <1%. I would run a sine wave through all 4 amplifiers in series at high noise gain, but only unity signal gain.. the handful of bad op amps would show up as unusually noisy or distorted.
Since those are long obsolete and were manufactured some time ago, I would test them 100% before ASSuming they all work OK.
JR
gar381
Well-known member
Thanks Guys for your comments.
I have seen other silver toped TI chips over the years as well.
There is a known boot legged run of 075s out of China but I
don't know if they are silver topped. I will be using these as
RC4136 replacements in a bunch of console modules rather than
the brown dog LA4 fix. 075s work very well in these modules.
I haven't had a chance to test these guys yet but will get to them this weekend
I hope these are good ones as 075s are becoming harder to find at low prices
and I got these fairly cheap.
GARY
I have seen other silver toped TI chips over the years as well.
There is a known boot legged run of 075s out of China but I
don't know if they are silver topped. I will be using these as
RC4136 replacements in a bunch of console modules rather than
the brown dog LA4 fix. 075s work very well in these modules.
I haven't had a chance to test these guys yet but will get to them this weekend
I hope these are good ones as 075s are becoming harder to find at low prices
and I got these fairly cheap.
GARY
bluebird
Well-known member
The TL075 has the odd pin configuration that 90% of quad op amp packages don't have. If they are rebranded TL704's you'll know pretty quick.
Not sure what they would use to make clones. Maybe the RC4136 which is four 741's with the same pinout.
Edit- Just saw that the RC4136 is what you are replacing, then you know.
I'm also now remembering I have a couple TL075's in my junk box that have silver tops and look just like your picture.
Edit again - I would actually beware of more noise when replacing a BJT op amp with a FET input op amp. Its a shame they don't make the 5534 in that package. It might be worth making little converter sockets and using MC33079's
Not sure what they would use to make clones. Maybe the RC4136 which is four 741's with the same pinout.
Edit- Just saw that the RC4136 is what you are replacing, then you know.
I'm also now remembering I have a couple TL075's in my junk box that have silver tops and look just like your picture.
Edit again - I would actually beware of more noise when replacing a BJT op amp with a FET input op amp. Its a shame they don't make the 5534 in that package. It might be worth making little converter sockets and using MC33079's
