Roland Phase Five AP-5 6 pin 741 opamp

Started by shzmm, October 21, 2009, 09:39:03 AM

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shzmm

Hello,

I'm trying to repair a Roland phase five for a friend and am having a problem identifying the pinouts for a 6 pin 741 opamp. 
I've done a search on this of course but can't find anything relating to the pinouts.  I do have a copy of the schematic which
I'll include so I can see where the output should be but I'm not getting a signal here. 
If anyone has an idea on this one your help would be much appreciated.

Thanks

http://img148.imageshack.us/img148/2776/rolandap5.gif

Mark Hammer

There are many things under the moon and stars that I am unaware of, but I have never seen a 6-pin 741.  14-pin, yes.  I have a few.  But 6-pin ICs other than optoisolators?  nah.  Is it possible that we are simply talking about metal-can style 741's with pins 1 and 8 snipped off?

shzmm

Thank you for your reply.  I included a photo of the little culprit. 
I dunno-- it says 741CE on it, the schematic says IC5 is a TA 741.  As to the possibility of the ends being snipped off?  It doesn't appear to be that way does it?
The strange thing as well is that the piece isn't that old-- the rest of the opamps are 4558s after all. 
http://s849.photobucket.com/albums/ab59/shzmm/?action=view&current=741.jpg

Hmm any thoughts on this one?


frequencycentral

The schematic certainly does show a TA 741 (IC5), I've seen some other gutshots which also show a metal can, but I can't see how many legs it has. Certainly pins 1 and 8 are not used on any 741, so maybe Roland did snip them off and Mark suggests. The clue would be that pin 8 usually has a small metal tab by it on the metal can IC's, so if there's no pin next to the tab.........
http://www.frequencycentral.co.uk/

Questo è il fiore del partigiano morto per la libertà!

Mark Hammer

I can't see any photobucket pix at work, but FC's advice is sound.

shzmm

Ok I had to pull it put just to see.  You were both correct in that two pins are clipped.  The pins simply follow the circle of the frame. 
In this instance the metal tab is on pin eight which is not being used but still present.  Pin 1 and pin 5 are clipped.
Thanks for helping me clear this one up-- now it makes some sense!