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Bose 1801 IC Question

hamrules

hamrules

AK Subscriber
Subscriber
I’m working on one of these and I know the original IC was a MC1556G. The one that is installed has this stamped on it:
S 7549
CR520T
The S looks like someone’s logo. I’ve searched on the interweb but can’t seem to find anything. I’m only looking just to find a data sheet for it. Does anyone possibly have any info for this ??

TIA
 
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Interesting site, so much out there. Unfortunately not what’s on it. I’ll post a pic although I don’t think it will help much.
 
IMG_3494.jpeg
Here’s the board.
I read somewhere that a .1uf Ceramic cap is suggested in parallel to the Zener diodes. Does this make sense to do?
 
The original MC1556G is a Motorola op-amp : file:///home/fp/Downloads/MC1556.PDF

I imagine the replacement on the board will have very similar specs.
 
I can't help with identifying your IC but I will let you know I'm in the middle of repopulating the amp boards on my 1801. They both had an MC1456 installed in lieu of the MC1556. No idea how they performed as the amp was DOA. Good luck with your project!
 
That’s good to know. Like I said I really was only looking for a data sheet on it just to see what it is. I’m going to populate one board and try to set bias & offset on it & if that works out then the other one. Probably another week or two.
 
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