Rag-time4's Duo repair project

[rag-time4]

I've finished replacing 90% of the caps on the board (doing total cap replacement) but one of the first ones I removed I am so far unable to replace. My problem cap is one of the 10uf caps near the sound amp. I have removed all the solder from the board and can't get new solder to attach to the board, and therefore can't get a replacement cap to stay in place. Here are a few pics:

If anyone has any ideas on how I can replace the solder please share!

[ogre]

Unfortunately it looks as if the surface mount pad is completely gone. The only possible solution may be to see if you can find the trace to it and solder that. First and foremost I would clean off the surrounding used flux to get a better view. There is a repair kit method
http://www.engineeringlab.com/smtpadrepair.html but it seems way to involved and expensive.

[nat]

Oh yeah, once you rip off that solder pad you're f*cked. I've done it many a time myself. Your only hope is to follow the trace and hope it leads somewhere close you can use as an alternate solder point.

[rag-time4]

Some new pics:

[Turbo D]

Grab a multi-meter and follow the trace of where the solder pad used to be (use the continuity setting, looks like this: -l>l-))) .) I imagine you can follow it to one of those holes that are in close proximity. If one of those holes works out, then you've scored as you can run one of your cap legs through it and solder away. Good luck friend. =D

http://www.ladyada.net/library/metertut/continuity.html

[kattare]

I had to get out my duo to trace the lead, but it looks like you can solder the pin into the hole that breaks up the cap outline.

-----X--
|           \
|            |
|           /
---------

About where the X is in my diagram, relative to your photos.

[Charlie]

If that circuit is the same as the TE (anyone know for sure?), go here:

http://www.pcenginefx.com/forums/index.php?topic=702.msg116301#msg116301

Charlie

[rag-time4]

I had to get out my duo to trace the lead, but it looks like you can solder the pin into the hole that breaks up the cap outline.

-----X--
|           \
|            |
|           /
---------

About where the X is in my diagram, relative to your photos.

Your diagram is a reproduction of the white outline that surrounds the missing cap, right? If so, the hole at your X is traced to the positive connection, there is another hole Y traced to the negative connection:

-----X--
|           \
Y           |
|           /
---------

I've put both legs of the cap through these holes, and attempted to solder them down. I'll post pics after dinner.

[rag-time4]

pics of the new 10uf cap in place:

[chop5]

took me half a day to do this:


http://img.photobucket.com/albums/v238/jetbue7/childdrawing.jpg


but i see others are on the same page 

[kattare]

chop!  love it!  heh

[esteban]

chop!  love it!  heh

Excellent diagram, pithy advice

[rag-time4]

I've got everything back together, but when I turn the Duo on, I get a grey or brown screen and an audio hum from the tv. Chop has recommended checking all caps for continuity. Anyone have any thoughts?

EDIT ~ I have 2 loose caps... gonna get those tightened and re-test.

EDIT II ~ All loose caps have been tightened... I found reversed polarity on one of the 47uf caps near the red led and fixed that. I've checked for continuity and everything looks good... but the 10uf cap that I had to emergency solder through the holes does not give me as much continuity with itself as the other 10uf caps. There is still some continuity, however. With the top half of the case off, I can see the CD ROM spindle start to spin, and I see a blink from the laser. Also, the screw holding down the white and green wire on the left side of the CD Rom broke off. These wires are normally secured to the metal around the CD spindle by a ring terminal, but since the top of the screw came off, the ring terminal can't be attached.

[kattare]

Can you confirm, with no card inserted, you do not get the usual bios screen?

Does anything change if you insert a card and boot up?

What process did you use to clean up the cap leakage prior to installing the new caps?  I wonder if you might still have a short somewhere from the leaked fluid.

[rag-time4]

Can you confirm, with no card inserted, you do not get the usual bios screen?

Does anything change if you insert a card and boot up?

What process did you use to clean up the cap leakage prior to installing the new caps?  I wonder if you might still have a short somewhere from the leaked fluid.

Correct, I do not get the usual BIOS with no card inserted. I get a grey or brown screen and an audio hum from the tv with no card inserted. If I insert a US hucard, sometimes I'll get different color screens (as in solid in colors other than brown and grey) but I'll get the same audio hum.

I used a moist cleaning towelette to remove the old cap juice that had leaked, and I also used a q-tip dipped in alcohol and dry q-tips to clean excess flux around the pesky 10uf cap in chop5's diagram.

Note: before my attempt at cap replacement, my problem was faint CD audio. Sound FX and other functions of the DUO were fine.