REPAIR GUIDE - TurboExpress: Sound Fix

[christoph]

whoa

those sites are awesome

thanks

[Duo_R]

If you replaced all caps in the audio circuit (circled green) your problem should be fixed.

So the sound and headphones were not working AT ALL on my Turbo Express and I did this mod - the sound now works in both the headphones and speakers - but its the infamous low sound. Low in both speakers and headphones. What do you recommend doing?

[christoph]

For anyone who was wondering where to order capacitors from - http://www.digikey.com/ - is f*cking awesome.

I ordered 40 various capacitors for $8.40 shipped. It arrived in two days. Great service.

[RoyVegas]

Trying to pick up a few caps locally to fix the sound on my Expresses...  Will a 100 uF 35V work for the sound fix?

[chop5]

thats fine roy,as long as its not under 6v from the original rating. i used a higher voltage on mine i remember cause i couldnt find 6v

[RoyVegas]

I've never done any soldering or repair work before but it seemed easy enough to give it a try.  Worked like a charm!  Thanks to guides and help from cool people on this forum another Express sounds good as new.  Thanks guys!

[Ichibanrei]

Thanks a TON for this guide.  I had scored on a PC Engine GT for 25 bux locally on craigslist of all places.  The sound was out but doing this mod brought it back.  So happy! 

[voidwhichbinds]

thanks a lot for this guide - I've finally gotten around to replace that 100uF capacitor, and it's fixed my TE's very low sound issue..

but for completeness, it should be noted that the highlighted cap in the photo on page 1 is used for the left channel audio - the other 100uF cap is used for the right channel...

[BlueBMW]

I thought the express just had a mono speaker built in?  I guess there's probably a second circuit for the headphones port.

[Charlie]

==>I thought the express just had a mono speaker built in?  I guess there's probably a second circuit for the headphones port.<==

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

Charlie

[Duo_R]

Charlie - this isn't exactly sound related, but what kind of part is at L502?

From what I can tell this helps switch power from batteries to external wall plug. I need to replace a bad part on one of my TE units but not sure what to replace it with.

[Charlie]

I'll check.
(Sorry I missed your message)

Charlie

[Charlie]

L501 and L502 are 1uh, .08ohm inductors on the battery input lines.  Looks like they are there for noise reduction purposes, so functionally you should be able to bypass them (short across them).  You don't even have to remove them!  However, they may have an effect on system noise performance. (But you may not care about that).  The easiest way to test that is to simply put a piece of wire in place of them, and see if you notice any negative effects, especially on the video display.

Charlie

[Duo_R]

thanks Charlie, is there a part i can replace those with? Or should i just try to jump?

[Charlie]

Jumping should work fine...functionally.  Just can't tell what may happen performance-wise.

If you want to find a replacement part:
1. Inductance should be ~.8uh to 1.5uh
2. Resistance should be <.12 ohms (lower = better)
3. Footprint must match size on board (DUH!)
4. Current-carrying capacity should be at least equal to that of a AA cell, more = better.
I wouldn't expect to find something that meets all these requirements, but there should be a reasonable compromise out there somewhere.

Charlie