2x Turbo Duo's completely Recapped - same problem low sound!

[Keith Courage]

I've changed all of the capacitors in the sound area. I have cleaned the pads with a wick and then rubbing alcohol, then applied new flux and soldered SMD capacitors on. They didn't work (in the sense that the sound level was scratchy and low), and I thought maybe one of the SMD capacitors was not sitting right, so I replaced them all with through hole so I could see they were definitely connected visually.

If the little 8 pin amps aren't working, are they stock parts? Unfortunately my cheap Chinese multimeters test leads fell apart, so I bought a fluke one, but that's at least 3 weeks away.

Thanks for help so far

Typically the amps don't go bad but if they do these work well. What voltages are you getting off of the ones in question? http://www.taydaelectronics.com/review/product/list/id/820/category/3/

[Steveodogbiscuit]

Thanks for the link.

I'm getting crystal clear sound through the headphones, but the audio to the TV is bad. It was bad before the recap and bad before the RGB mod.

I hot aired both amp chips off and cleaned up and put them back. I'm without a tester as my leads have broken, so I can't test the voltages on the legs right now .

I'll keep digging to see if I can find a solution.

[cloudd]

Duo #1
1. I have jumpered power / gnd on all 4 op amps = no success
2. taken　all 4x op amps off cleaned check the vias underneath the one = no success
3. checked the power at all op amps it is is 8.9v approx

When my sound is working the other pins on the the 1 op amp (top of board left top coner by av) is giving 3/5v approx on other pins other than ground. when the sound drops these voltages are approx 0.6v approx


Result at this point=
The sound amplification circuit is faulty and seems more faulty when the cd-rom games play (this could be be false by saying this. its just faulty). It cuts out and  very low or sometimes scratchy sound. It must be the amplification circuit turning on and off.

If I could just jump the sound into another amplification circuit I make. Possibly buy one off of ebay that would be awesome. I would not know which one to buy or how to create this one with which parts. Does anyone have any other ideas?

[HuMan]

Your Duos could be like mine where they have accumulated corroded via damage in the past. This isn't the best method, but I found two corroded vias just by holding the Duo mainboard up to a light and looking for light coming through each via, corroded ones will be filled. What I do to confirm is touch both leads of my multimeter into each side of the via, no connection means I jumper the bad via.

Don't give up on the original circuit just yet, the problem just needs to be found. It worked at one point, it can be made to work again.