Author Topic: REPAIR GUIDE - TurboDuo: Sound Fix  (Read 16625 times)

D-Lite

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REPAIR GUIDE - TurboDuo: Sound Fix
« on: August 31, 2005, 05:27:27 PM »
Yes, you read that right!!

Note that this is a fix for a SPECIFIC sound issue, but the big one.  For this to work you will need to PROPERLY identify the problem with your system.  There is more than one problem that can occur with Turbo Duo systems and I think this is going to work for many.

OK, the problem and diagnosis.  Here are typical issues with Duo systems:
1.  CD plays and loads fine, but all redbook audio (soundtrack, not sound effects) is dead.
2.  audio is scratchy and may fade in and out, but the CD games load and play no problem (well, except for sound, duh)
3.  CD play is sketchy and the drive sounds like it's struggling.  More than just a sound issue

This fix seems to work mainly for the #2 case and maybe for #1.  I need to test more systems though to be clear on what it works on.  It should work for both, but I won't commit to that without further study.

So, some of you may have seen my hypothesis about what the sound issue is due to and after struggling for a way to prove it, I've finally found a way to study it.  I blame the sound issue on overheating with the Duo model and have stated that the later DuoR and RX should be problem free due to placement of the audio components in relation to the heat sinks.  But how to study the problem when you need the CD drive running, yet the cover off?  The CD lid is required to keep the CD spinning.

At this point I'd like to take a moment to mourn the loss of a PC Engine Duo that gave it's life so others may live:


I cut the top up so I could test the components while running.  Don't worry, the unit itself was already dead anyways.  

OK, so, look at the area need the heat sinks:

In the yellow circle I highlight key components.  The 10 uF caps on the left and right are controlling the left and right channel pre and post amp.  The little 8-pin chip in the middle is an op-amp that is needed to process the sound.  After tapping around on these, I found that the POST op-amp caps are indeed the ones responsible for the sound level and the scratching you sometimes hear.  Sweet!  These come from an era in the early 90's when there was rumored to be a problem with capacitor production.  Dry cap likely.  This is the same issue as with the Turbo Express that I covered before.

So then I ripped the bastards out and soldered down a couple of brand new 10 uF, 50V caps:

Simple as hell and cheap, <$1 for the parts.  Of course you need a special screwdriver bit to even open the thing, but hey....

And that's that!  As said, I'm still working on what can and can't be repaired with this problem.  More details will come when I can figure that out too.

And as it turns out I am figuring out how to deal with problem #3, wonky CD drive performance.  Hallmark is the grinding, whining, whistling, stopping, grunting CD drive and game pausing, slow loading.  There are 5 little screws in the unit that directly effect the drive performance so hopefully that will be fruitful.

Major thanks to Saibot and monads for supplying Duo's to look at.  Hopefully I can fix theirs too.
« Last Edit: March 05, 2009, 12:02:30 PM by Pcenginefx »
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rolins

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TURBO DUO SOUND FIX!! (56k beware)
« Reply #1 on: August 31, 2005, 05:49:57 PM »
Excellent work D-Lite! When will you be able to take orders?

esteban

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« Reply #2 on: August 31, 2005, 06:17:55 PM »
Absolutely fabulous work, D-Lite! And the presentation of your post, including the photos, was simply killer. THANK YOU :D
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larsulrik

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« Reply #3 on: August 31, 2005, 06:57:28 PM »
Awesome!  #2 is me (even though I mentioned a couple of weeks ago letting it run for a while temporarily fixed it).  Do you think the overheating will still be an issue with the new caps or was that just something the old caps had problems with?  Thanks Chief!

dj898

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« Reply #4 on: August 31, 2005, 06:58:34 PM »
good to see we still have PC Engine/Turbo gurus around... :D

D-Lite

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« Reply #5 on: August 31, 2005, 08:57:47 PM »
Quote from: "larsulrik"
Awesome!  #2 is me (even though I mentioned a couple of weeks ago letting it run for a while temporarily fixed it).  Do you think the overheating will still be an issue with the new caps or was that just something the old caps had problems with?  Thanks Chief!

I think the main issue is the old caps suck.  I've seen beautiful Duo's have the sound problem.  I've seen MANY Turbo Expresses with dead caps too.  The problem is likely due to the quality of the capacitors themselves so the new ones will probably be more robust for longer times.  

I have a couple systems on hand that have flakey sound.  Sometimes I run it for 2 hours straight and no problems!  Sometimes it's screwed from the start.  Hard to figure out the problems when it's like that, like your system that gets better with running.  Perhaps something causes it to build enough of a charge that it'll work, who knows.  The good thing is, doing this little repair can only help, not hurt.
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zborgerd

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« Reply #6 on: September 01, 2005, 04:08:22 AM »
Nice work!

DragonmasterDan

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« Reply #7 on: September 01, 2005, 08:44:32 AM »
Though I dont have a problem with the sound on my Duo, would this be a good thing to do for preventative maintanence?
--DragonmasterDan

esteban

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« Reply #8 on: September 01, 2005, 10:05:03 AM »
Quote from: "DragonmasterDan"
Though I dont have a problem with the sound on my Duo, would this be a good thing to do for preventative maintanence?
Ahhh, good question, Dan.
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Keranu

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« Reply #9 on: September 01, 2005, 10:34:42 AM »
Well done again, D-Lite.
Quote from: Bonknuts
Adding PCE console specific layer on top of that, makes for an interesting challenge (no, not a reference to Ys II).

D-Lite

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« Reply #10 on: September 01, 2005, 11:15:47 AM »
Quote from: "stevek666"
Quote from: "DragonmasterDan"
Though I dont have a problem with the sound on my Duo, would this be a good thing to do for preventative maintanence?
Ahhh, good question, Dan.

Not necessarily good or bad.  It's simple enough so sure you could, but I'd wait until the problems start.

I've been testing out a system that has no volume at the start and then comes in within 15-20 seconds of play and persists well.  Again seems to be a capacitor that is poorly charging.  This will/should address #1 above, I hope, to some extent.  I have another Duo here that is highly unpredictable in terms of #1, so that is my big challenge.
Check my site for Turbo, Neo, NGPC, and superguns!
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Black Tiger

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« Reply #11 on: September 06, 2005, 02:43:37 PM »
Quote from: "D-Lite"
Quote from: "stevek666"
Quote from: "DragonmasterDan"
Though I dont have a problem with the sound on my Duo, would this be a good thing to do for preventative maintanence?
Ahhh, good question, Dan.

Not necessarily good or bad.  It's simple enough so sure you could, but I'd wait until the problems start.

I've been testing out a system that has no volume at the start and then comes in within 15-20 seconds of play and persists well.  Again seems to be a capacitor that is poorly charging.  This will/should address #1 above, I hope, to some extent.  I have another Duo here that is highly unpredictable in terms of #1, so that is my big challenge.



I'm so glad that there are people like you that not only have the know how, but also give a damn about a system like the TG/PCE to do things like this.
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grendelrt

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« Reply #12 on: June 23, 2006, 02:05:34 AM »
I know I am reviving a dead thread, but I think this a good thread to keep at the top.

I was wondering a couple things. This will be my first undertaking of modding a system. I was wondering the best way to remove the original capacitors? Also I noticed D Lite replaced a third capacitor at the bottom (not one of the two he pointed out), does it need to replaced as well. What wattage soldering iron should I use (specific solder?)? Right now my duo every once in a while has the sound fade in about 20 secs after start up and some scratchy audio issues, both of which it seems this little mod will help. Any other suggestions would be appreciated.

grahf

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« Reply #13 on: June 23, 2006, 07:21:10 AM »
grendelrt, try some fresh desoldering braid and a good fine tip iron. A touch of flux may help if the braid has trouble getting started. It may be a tight fit to get to some of the caps. Then when youve got them pretty clean, just heat and lift each side lightly alternatly until it comes off.

grendelrt

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« Reply #14 on: June 23, 2006, 07:46:25 AM »
Cool thanks =)