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BA662F vs BA662
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author BA662F vs BA662
fivesteppath
Would anyone have any information pertaining the BA662F?

I have an one of the original voices from a Juno106 laying around, that's been cosmetically damaged beyond repair, although the IC's themselves should work fine with additional cleaning. There are two BA662F's on it and I was wondering if it's possible to use these as a replacement for the BA662 in the TB303 (clones) for instance.

Although having a difficult time understanding the difference between the BA662F and BA662, I imagine the F version is identical apart for being SMD, but it does have 14 pins in relation to the 9 found on the BA662. I cannot find the datasheet on the F either.
guest
yes, the F variant is the SMD version. you can follow the traces to see what pins go where. you can double check with a multimeter for some of the pins as well.
fivesteppath
guest wrote:
yes, the F variant is the SMD version. you can follow the traces to see what pins go where. you can double check with a multimeter for some of the pins as well.


excellent! any idea what purpose go to the 5 extra pins?
guest
they are unused. its similar to the ba6110:

http://www.firstpr.com.au/rwi/dfish/TT-303/click-fix/BA6110-datasheet- with-SIP-9.pdf

the BA662 in some of the synths are selected for low offset voltage or matching gm parameter, so it might not work perfectly depending upon where its going. for example, in the 303 VCA there might be slight clicks if it has too large of an offset voltage. this can be fixed with an external trimmer.
guest
by the way, i found this, so someone has done it before:

http://freidreher.com/assets/images/ba662f-2000x1332.jpg

you can make out where some of the connections go on that pcb:

thmt - smt
5 - 8
6 - 9
7 - 11
8 - 12
9 - 14
fivesteppath
guest wrote:
by the way, i found this, so someone has done it before:

http://freidreher.com/assets/images/ba662f-2000x1332.jpg

you can make out where some of the connections go on that pcb:

thmt - smt
5 - 8
6 - 9
7 - 11
8 - 12
9 - 14


Thank you thank you!
guest
ok, here are the rest, from looking at this image:

http://www.studiorepair.de/files/images/gallery_thumbs/8-8.JPG

thmt - smt
1 - 1
2 - 3
3 - 4
4 - 6,7*
5 - 8
6 - 9
7 - 11
8 - 12
9 - 14

rest of pins not connected to anything internally (cant say for sure on pin5, but most likely so).

* i cant tell whats going on here. either they both need to be connected, or its just one of them and it made routing easier (which it doesnt really). if i had to guess, it would be 6 that is used. if you get one off, could you take some measurements and report back? measurements must be taken with it off the board, though, not on the board.

1. what is the resistance between 6 and 7?
2. if resistance is non-zero, do a diode test between 6 and 8, and then again between 7 and 8. what are these voltage readings?
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