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840AV identify missing IC @ U9
Posted by: Bama on 2020-08-28 11:23:39
Hello All,

I need your help to identify the IC part number located at U9 on my 840AV logic board.  I recently purchased this 840 from eBay as not working and I started removing the leaky SMT electrolytic capacitors.  I discovered that the IC at location U9 is missing.  Bomarc schematics appear to have it as part of the analog sound circuit for the headphone output.  I have uploaded a picture of its Empty location.   Please share it’s part number, so I may purchase a replacement.

Thanks,

Bama

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Posted by: Bama on 2020-08-30 00:48:04
I decide to upload a better picture to more clearly display the location.

If you have access to a 840AV, please upload a picture of the IC at U9 with the part numbers visible or if you are savvy then please recommend a replacement or where to learn the data for this missing IC. 

🙂

Bama

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Posted by: Bama on 2020-08-30 09:30:02
Newbie alert!  

I need your help.

If you are adept at reading schematics and choosing compatible parts, then please share your opinion on U9 in the schematic and the proposed Op-Amp data sheet image.  Maybe this sparks a memory of the correct part number...maybe you saw this on another vintage Mac?  

My Google searches for "Macintosh op-amp""Quadra Op-Amp"or operational amplifier....nada.  Searching google images for 840AV and other vintage Mac logic boards only yields blurry pics of 8-pin IC's.  

Thanks for reading another post in the saga.

🙂

Bama

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Posted by: Bama on 2020-08-30 11:59:03
Update:

I scanned the 840AV YouTube videos by Branchus Creations To look for screens of the U9 IC.   I was able to screen capture two examples which look to indicate it’s a

TI - 2082C.  I was able to find similar on Digi-Key, TLE2082CD.

 https://www.digikey.com/product-detail/en/texas-instruments/TLE2082CD/296-10444-5-ND/381008

Is this the correct replacement part?

Thanks for sharing your experience and insights,

Bama

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Posted by: cheesestraws on 2020-08-30 17:36:57
The schematics do show it as an op amp so that looks perhaps reasonable?  I was confused by the curved back of the op amp on the schematics, but I just found a footnote in a book on them that suggested that that's just an old way of drawing the symbol, and doesn't actually mean anything special.  Also, the pin numbers on the schematic line up with that diagram of the TLE2082 from the datasheet.

So in the absence of any other info, I'd give it a go, personally.
Posted by: jeremywork on 2020-08-30 18:18:38
I just dragged this one in from ebay, it needs some attention to say the least but confirms your part number. 

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Posted by: Bama on 2020-08-30 21:10:12
Awesome, thanks y’all!!!

I will purchase the that IC and some replacement capacitors and cross my fingers!

🙂

Bama
Posted by: Phipli on 2020-10-04 01:52:18
Bit late to the game sorry 🙂 Just sharing a picture to give a bit more info to verify. Besides, I was stood right next to a bare 840 board when I read your post.

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