Helping a friend

[VanDerchuck]

So, I'm trying to help a friend out. I fixed one of his favorite pedals a couple years ago. MXR Phase 90, script logo, bud box. He had shipped it to a friend to use. When it arrived it was dead. The input buffer ic, input cap, and the third ic in the phase shifting stage were all dead. Started with the cap, then the input ic, and then the phase shifting ic. I changed them in that order to make sure I didn't do something I shouldn't have.

I tested it out, and everything was working. I gave it back to him thinking I just did him a solid. He said thanks and that was that. Come to find out it didn't sound the same to him. He couldn't really explain it, but from what I gather it didn't sound as vibrant as it used to. And with his lack of electronics knowledge I'm not sure he's blaming me for the parts that I used. So I took it back. I socketed the ic's so I've been trying different ones to try and find something that sounds best. TL071 sounds best so far so that's what I've gone with.

I tested the phase circuit with my signal tester and I get phase at each ic.

I sat and listened to is swirl by itself with just a guitar plugged in and I noticed that the pedal drifts. Sometimes the swirl gets really loud and sometimes it is really quiet. If I unplug the guitar and plug it back in the pedal sounds at its best for a short time and then it drifts off again.

I'm thinking the two tantalum caps are starting to drift and that is causing some of the issues.

The question is, if I have to change anymore of the caps then what should I use? I used a Panasonic film cap for the input cap.

Thanks for any help