REPAIR GUIDE - TurboExpress: Sound Fix

[grahf]

For anyone with the means to solder smaller stuff, you can get the SMD caps identicle to the bad ones at mouser.com. Im pretty sure thats where i got mine. Im going to replace ALL the caps in my nicest unit.

[grahf]

Well, I replaced all four caps in the audio amp circuit. The result is perfect sound. This thing is LOUD, way louder than my DS or GBA. I cant believe this is how its supposed to sound, after listing to it in wisper-mode all this time

I was mistaken, I got the caps from Jameco. I can provide part numbers if anyone is interested. The hardest part of this job is removing the shields. A bit of desoldering braid is needed, and a fine tip soldering iron is a MUST. The picture below is of my parts/project GT, and has the handsfree jack removed as well. You dont need to remove it (I didnt on the one I did today), but it would give you more room. I'm going to go back in later and replace the rest of the caps for good measure.

[FM-77]

What the hell happened there in the corner?

[grahf]

Some parts of the PCE GTs come coated with this rubbery/glue junk. I just scraped it away a bit to see underneith on this board.

[esteban]

What the hell happened there in the corner?

Obviously, the marshmallow he was eating fell from his mouth and melted on the board.

[grahf]

you know, for the most part the Express/GT is very well constructed (just like the PCE). But i cant for the life of me figure out why they felt the need to cover certain things will goop. Its common practice to coat some things, but not just randomly glob it on there.

[Michael Helgeson]

They did it to insulate that area I guess,assuming it is a more high risk area of the pcb component wise.

[grahf]

Yeah, but one must wonder why they didnt just use the common shellac style coating. Maybe they thought the glue would help the heavier components from jolting loose from a drop.

Or, maybe someone brought their kids into work with their elmers glue bottles

[Tatsujin]

question: isn't it just that easy to replace only this 100uF/6V capacitor?

:edt: grahf already mentioned about that. fine


btw: did someone try to use doublelayer/tantalum capacitors instead of electrolytic, since they can't dry out, which causes the problem of losing the sound. of course i'm aware, that for audio applications there isn't something better than the good ol' electrolytic caps. but we're not talking about HIFI here

[Tatsujin]

Yeah, but one must wonder why they didnt just use the common shellac style coating. Maybe they thought the glue would help the heavier components from jolting loose from a drop.

Or, maybe someone brought their kids into work with their elmers glue bottles

seems like it's the part for stepping up the voltage which is needed for the neon-lamp for the backlight (about 100VAC). sometime parts, especially coils have to be fixed/reinforced with some glue to the PCB, since they shaking slightly in a high frequency, which could cause a broken soldering over the time of use.

[ctoomey]

I've done this on a few units with success but experience a bit of 'hum' in both the speaker and when listening through headphones...I have not pulled the dry/old capacitors since it doesnt seem necessary and I am using 100uf 50V capcitors...

Thoughts on how to limit the hum?

Thanks!!!

[grahf]

I get the same hum, and im pretty sure its normal. I dont know how it is on yours, but on mine it only occurs when the volume level is pretty high. My portable dvd player does the same thing (as do a lot of electronics).
It is also possible that one of the other dry caps on the board is allowing interference to bleed into the audio. When I have time I may replace all the other caps on the board, but its no rush because it sounds normal to my ears.

[Tighe]

Hey D-Lite, I just wanted to say thank you for posting such an informative (and picture filled ) rewiew and also i wanted to say that the sound fix works wonderfully. now if I could just figure out how to do the screen fix...
Anyhow, many thanks!
M.

About a year ago my beloved TE's sounds kept getting quiter and quiter, until one day the video stopped being displayed too!  I was so sad and knew if I spent a lot of time I could figure out the faulty circuit, but I just didn't have that time.  After reading this post, I was so excited I ran to the basement and replaced the capasitor as suggeted, and WOW the sound was back!!!  Now the real question is will replacing all the capisitors return the video?  The backlight still works, I can ouly assume that the problem is with the main board not the video driver.  I will be ordering exact replacements as they will be much easier to install.  I will post here with the results.  Thanks D-Lite!

http://nestable.classicgaming.gamespy.com

[ctoomey]

Cool! Where are you ordering the replacement vid caps from?

[ctoomey]

Grahf, I was curious why you replaced all 4 of the caps...It seems that just following D-lite's sound fix works well, even if you leave the old ones in place?