Very low sound after Duo re-cap

[Jugbug]

I was wondering if anyone might be able to help me out, or at least narrow down my search.

I recently replaced all the caps in my US Duo and now the sound through the AV and headphone jacks is barely audible.  From what I can hear it sounds like left and right are at the same level, and all the different types of audio are being played.  The headphone volume dial also controls the volume a bit, from barely audible to... even less so.  There's also a noticeable speaker thump when I turn off the system, although I can't say if that's new or if I'm just overly paying attention to things now.

The system lost audio about 8 months ago which I quick fixed by replacing C604 and C610 (the two marked as post op-amp in D-lite's thread).  The system has been fine since then aside from some crackling that would go away after a few minutes.

There were quite a few bad caps, but everything cleaned up nicely for the most part, except for two spots where the cap fluid seeped along traces under the solder mask.  One was below C135, which is a fairly thick trace and seems to be ok.  The other was C612 which lifted the trace below it a bit when I removed it.  I wired the replacement cap's negative to C305's negative, and the positive to pin 8 of the M51131L chip above it.  I hope these are the correct points, as the black cloud left from the cap fluid makes it a little hard to distinguish the traces.

I've been checking traces and vias for continuity, particularly to/from 4558 chips, but so far haven't found any problems unless I overlooked something.  Any advice or suggestions would be appreciated.

[Jugbug]

It looks like R322 and C621 were open.  I was able to get R322 connected to its pad, but no luck with C621 so I wired it to R322.  This restored my sound to normal.

However, now my CDs spin up but don't seem to be recognized.  The laser keeps moving back and forth a little near the inner edge.  Maybe I bumped a pot while cleaning the PCB. 

[BlueBMW]

Sometimes cap replacement can change the laser control circuit some to where you may have to make an adjustment.  Though it shouldnt need much of an adjustment.

[Jugbug]

It was working after the cap replacement, but before my audio was restored.  Not sure when exactly it stopped as I was leaving the CD drive disconnected while working on the audio issue.  Working through the laser adjustment thread here to see if I can get it recognizing CDs again.

[Jugbug]

Got it to recognize an audio CD and its tracks, but playing it causes it to skip all over the disc rapidly for awhile and then stop playing.  Are the pots more or less independent of each other, or after adjusting one might I have to go back and re-adjust a previous one?

[BlueBMW]

I wonder if somehow the drive assembly got knocked out of whack while removed....  Check the position of the spindle motor table and make sure it hasnt been pushed down too low by accident.  Also, make sure that your wires arent catching on anything while the laser moves down the track.  Resistance will cause skips.  You may also regrease the rods that the laser slides down, in case they got cleaned off / dried off during the whole disassembly. 

Regarding the pots....  I'm not sure how much they relate to one another, but there is definitely an order to their adjustment.  I start with VR102 and VR104 until I get the disc spinning and at least attempting to read / play.  Then I move on to VR101 and VR103.  Lastly I adjust VR105 until I get good playback even on later tracks of a disc.

[Jugbug]

My CD drive seems to be mostly back in action.  I had trouble getting past a certain time point on one audio CD, but another CD had no problems beyond that same time point.  I'll have to do some extensive playing and see how things go.  I still want to do some tweaking and see if I can't get rid of a noise that I don't think was there before.  I didn't change VR102 or VR104 as my discs were still spinning.  I had to change VR101 and VR103 a bit, and alot of changes to VR105 to try to find just the right spot.  I appreciate the advice on the pot order, although I already got it from your contribution to the laser adjustment thread.

And just to make sure, is the laser supposed to move back and forth slightly while reading a track?

[BlueBMW]

Yeah, the laser eye will move around quite a bit during playback.  Its just tracking the disc.

[Jugbug]

Thanks for the advice, and for answering my questions, Blue.