[seanohue]

So I've got a PINT that I've been sort of putting off doing and I've decided to try and fix it. The problem with it is that the music plays, but it sounds strange. First of all, it only works if the source's volume (in this case, a 5G ipod) is at max and the amp's volume is at the minimum. The sound is fuzzy and it makes a clicking noise as the bass (and don't worry, I'm using iBuds as my ginea pigs

) This one has had the Mini^3 mod; cut has been made, jumper has been done, and the caps/resistors have been stacked. Here's some pics:




Today, I cleaned the board up with isopropyl alcohol so the white spots in some of the pics are now gone. My best guess to a problem is a gain issue or a grounding problem. Let me know what you guys think. Gain is currently at 4 with a 1.33k and a 4k in R3 and R4, respectively.

 

[IEATTEFLON]

Is there a chance that you overheated the opamps or capacitors? A lot of the surface mount components seem to have excess solder.

 

[Pars]

Sean,

In the top pic, looks like a possible bridge on the upper opamp pins 3-4 and the lower one pins 7-6. Clicking noises might indicate oscillation... do the opamps get hot (AD8397s probably do anyhow)? What does the current draw look like? Does it jump up as you turn the volume up?

Chris

 

[seanohue]

In that pic the top op amp does look jumpered but it is not; the mini^3 mod involves the jumpering of pins 6 and 7 in the bottom amp. I don't have anything to measure the current draw atm and by changing the volume (either lowering it from the source or raising it from the amp) cuts off the sound completely. None of the components appear to be overheating either.

 

[seanohue]

Heres a great pic

 

[seanohue]

Heres another interesting thing I just discovered. It won't play a quieter part of a song. For example, I have "The Accolade II" by Symphony X and the beginning was completely silent (when it is a piano opening) but the sound came back once the heavy part kicked in. Op-amps are warm, but not hot, so I don't think they're occilating.

 

[tomb]

No offense, but it looks like there are other bridges, too. The trace may not be completely cut, either, and it looks like it may have sliced some of the Ground tracing, too. As for the solder - it looks too cold, not too hot. I would dump some flux on the board and reheat each joint with some braid until you get rid of some of the blobs. Good luck.

 

[seanohue]

alright I'l give it that a try.