Peculiar Duo Sound Issue *After Cap Replacement*

[Dangerboy]

Long time admirer, first time poster!

So I'm not sure if I'm losing my mind or not, figured I'd post this and let others weigh in.

About a year ago, I got a cap replacement for my Duo done by Retro Game Cave. Came back amazing, sounded like it was Day 1 out of the box. Totally happy. About 2 months later, I had to pack up and move into my parents basement while I was waiting for eventual condo purchase to go through. A Year later, I moved in, finally got game room set-up, and hooked up the Duo. That's when something seemed...off.

Here's what I'm running into. The CD audio is perfect, loud, crystal clear. It's the sound effects; depending on the game, some or all are soft. Especially compared to the CD audio. It's also not consistent.

- In Rondo of Blood's opening, you can barely hear the "Hyah" "Hyah" from the main character or Grim Reaper's few sentences. All other sound effects, like the whip, horses, explosions sound fine.
- In Riot Zone, both sound effects and voice are soft.
- If I play a HuCard, all sound is even across the board.

I tried 2 different AV cables. Same results if you plugged the headphone jack to speakers.

I hooked up my TG16CD, and Riot Zone's speech / punch effects are clearly louder.

The question is, am I just remembering the Duo's sound quality wrong? It's been forever since I had played it - or is this the sign of another cap going out somewhere on the motherboard? I'm assuming there's no sound adjuster pots to futz with, right?

Any help would be greatly appreciated. Thanks!
Jason

[Bernie]

Are you using actual discs, or CD'R burns?  We have enough techs here, that is there is an issue, they will get ya running again.

[Dangerboy]

Answered in the order I saw them...

"CDRs?"
1. Only real discs. None of that funny business for my baby. Rondo of Blood is the only import I own aside from the two Aim for the Top! Gunbuster games. Old anime fanboyism dies hard.

Opened her up?
2. I actually do own the gamebit, and I did open her up...to a degree. I'll explain below

From removing the lid, it's clear RGC did all the upper left corner cap replacements, and what looks like one or two random ones around the board. All are clean, damn near standing straight up jobs. Amazing work.

All the original small grey surface mount caps that I see being culprits in other situations all look clean. However, there is something I did notice that I should have taken a photo of before reassembling her it.

One of the small silver / grey rectangle caps(?) just under the shielding looked like it had a weird substance ever so faintly visible next to it on the board. Grossest description would be an ear wax color - brownish yellow. I swabbed a q-tip over it, but it didn't pick anything up. In the picture here: http://i130.photobucket.com/albums/p266/Rockguard/PCEngineDuoTotalCapReplacementRefer.jpg it would be the grey roundish rectangle above the controller port and blue thingies.

Since I was too afraid to undo the cabling, I only just barely lifted up the board to look underneath. It looks like something similar to the mystery substance is on the underside of the board, left of the HuCard's slot. It's not visible at all on top, and I couldn't tell if it was just weird lighting effects.

Considering there are many of the original grey caps still in play, I think I would just have the rest of them replaced, but wanted to make sure this issue would be fixed within that solution. The CD laser is brand new, works flawlessly.

The follow up question would be who you would recommend to send her it to for the Cap Replacement on the rest of the board. I am a huge klutz, and do not allow myself near anything hot, burning, or that could cause damage to vintage, babied systems.

Thanks in advance, you guys rock!

[Bernie]

Yeah, thats what is going on.  You got some leaking bitches in there.  Get with thesteve, turbokon, or bluebmw here in the forums.  Easy fix.

[Desh]

Just for shits unplug the sound jacks to your t.v. one at a time while a game is playing.  By the description it sounds like the audio issue may only be on one channel.  Regardless, if there are still original caps in there they need to be replaced.

[Keith Courage]

Honestly I think your cd drive lens rails need cleaning or the lens just needs adjustment. providing all the caps have been changed that is.

[Dangerboy]

I tried with headphones plugged directly in. Same sound issues. Will contact one of the mentioned helpful folks as soon as I can.

[Keith Courage]

Honestly I think your cd drive lens rails need cleaning or the lens just needs adjustment. providing all the caps have been changed that is.

his symptom is that cd audio is louder than chip/psg/whateveryoucallit. And his observation was that only some of the caps had been replaced, and some of those that hadn't been replaced are pissing on his board.

I say this only because there is a pretty big wall of text to parse and I wasn't sure if maybe you missed that. If I'm mistaken amd you did catch those symptoms, I'd be interested to learn about the reasoning behind your suggestion. I'm a crap tech and try to soak up whatever wisdom I can!

Ah, I did miss that. I didn't see the 2nd message on my phone earlier. Change the rest of those caps. I've come across symptoms of some sound effects not loading correctly or just cutting off due to CD read issues but I'd start with the rest of the caps.   

[majors]

Sounds like an issue I had...ADPCM sounds were not present. Buster Bros was the easiest game to notice b/c all the sound effects in game use that chip/function. Also, in Gate of Thunder, there would no explosions or weapon power ups "names". On the 4-in-1, you would not hear Bonk in the game selection say the "Uba Bonk, doba player" nor the name of the game once chosen. I sent it off to Chops and he said caps/vias/leaky something or other. Definitely fixable!   

[turbokon]

Check the traces or via's for the 10uf and 100uf caps by the adpcm chip. If you have a bad adpcm chip, you won't get any sounds affects at all.

[Necromancer]

+1 on getting the rest of the caps done and more importantly cleaning off the cap juice.  A cap job isn't of much use if cap juice is left behind to cause shorts and eat the pcb.