NEC Turbo or PCE Duo sound problem- a REAL fix perhaps?

This is starting to drive me nuts. I'm getting e-mails about fixing the heat related sound issue that some Japanese and US Duo's suffer. There has got to be a fix, since it's obviously heat related.

I know this is D-Lite's forte, and I'm hoping he can share some of his hard won R&D on this topic.

The Problem:

You play your Duo, doesn't matter if it's HuCard or disc. Around the two hour mark, the sound starts to crackle, before it fades out completely. In fact, the sound is not really *gone* but it's volume is SEVERELY reduced. If you crank the reciever you have the Duo attached to, you can still hear the sounds, slightly distorted and very quiet. If you let the unit cool down (I mean waaaay down, 2 hours +), it can be restarted again, with full sound function, but the problem will re-occur in a shorter time period.

In my opinion, this just screams *heat problem*. What's odd, is how long it seems to take to cool down, for the problem to go away. I suppose this could be heat affecting the IC that controls the sound, but I'm guessing No. The sound is still there, just quiet and lo fidelity. I'm guessing the heat is affecting the amplification parts of the circuit.

I'm going to start theorize about things I only partially understand, so bear with me.

If it's the amplification that is cutting out, then does that not point to the problem lying with the capacitor (or capacitors) in the sound amp circuit? Can heat adversely effect capacitor function? If it's not a capacitor failure, what other component in the circuit is more likely to fail under high heat conditions? There are a LOT of caps in VERY close proximity to the heat sinks that are trying to dissipate all of this heat.

As I venture further into guessland, what if I replaced the cap or caps that function in the sound amplification circuit? What if I relocated them elsewhere, by simply removing the existing ones, replacing them with same rating caps, and running wires to the new locations (ensuring accurate polarity of course)?

Am I onto something here? Is there something in the amp circuit more likely at fault that may benefit from a relocation?

I've considered active cooling, but then you get into a case mod, which would likely ruin the clean lines of the Duo, plus add noise. There has to be a better fix.

If I'm making some sort of big assumption, or am making some obvious error, I would LOVE to be schooled. That's why I'm posting.

Any ideas peeps?

I have never heard of this problem before - How common is it?

I have a classic PC Engine (well, CoreGrafX) with attached cd-rom, and I've never had the problem. Is it general for all duos (of a certain model)?
Sounds like NEC did a really bad job.

It's a common Duo complaint.

Hmmm.... I've never had this issue with mine even with playing Dracula X and Y's 1-4 for many hours straight.

The only problem mine commonly has is the game freezing because the disc loses its place. A gentle tap on the unit or on the counter where it sits helps it resume without much trouble.

I some time lose music, but that's due to a similar problem as the one posted above. Saturn is much worse at it though (and does it with music files too, *cough*parodius*cough)

I did send a synapsis of what I think is the problem in a letter the Turbo-List about 8-9 months ago, but you may not have seen that.

I'm 99.6% sure the issue with the sound circuit is due to overheating as you say. One way I am trying to combat this issue is with a preventative measure, installing a fan. I've installed fans on 3 different Duo's now and all reports are that they work really well. If I can find the pics I took, I'll post them. I install the fan where the AV port currently is, removing it in favor of the S-Video and RCA mods I do too. This fan is then situated right next to the enormous heat sinks in the original model Duo and the heat dissipation is very noticeable. The top of the Duo above the HuCard slot typically is very warm to the touch within 15 minutes of play time, but with the fan on this never heats up!

Now, why does this/should this work? Well, I've noticed a very important fact. Original Duo systems are MUCH more unreliable than Duo-R or RX systems. Why? The CD units are identical. BUT, the AV port is in a different location whereas the heat sinks are still in the upper left. Upon closer inspection, the amps for the sound are DIRECTLY behind the heat sinks on the original Duo but not on the R or RX! The amps are this small 8-pin SMTs and include a couple of caps as you mention potentially being the cause. I did some research on the chip and it is a audio amp circuit, but wouldn't ya know it, is only rated to 80 degrees! Not good my friends. I've bought some of these chips to try and the caps are standard fair.

But.

The problem is that the sound issue is separate from the CD read issues that some people see, yet this is difficult to diagnose. I believe I currently have in my possession a Duo board with ONLY the sound issue. This is because I found it while modding a system for someone, swapped boards, and now received it back to play with. It is critical that the difference between the sound and CD issues be clear when attempting to solve the problem which I now think i can do.

So, long explanation/theorization/rationalization. No data to prove it works. Yet

That's awesome D-Lite! 8-)


I'm going to look at moving the sound amp circuit, just for the hell of it. See if there is more than one way to skin a cat.

I just took a quick look at the board with the fresh eyes you' have given me.

I'm assuming the amp IC is the one at R691 . The IC itself the small 8 pin 4558 2908.

For the hell of it, I may still try to move it. however, I can see the elegance of the solution you've done by moving the AV jack. Even without an S-vid mod, it's easy enough to tap composite and audio from a removed A/V port, and mount jacks elsewhere.

Thanks again!

omnedon said:

It's a common Duo complaint.

Click to expand...

Talk about an understatment. I got rid of my Duo as it had that problem. Gonna get an RGB modded Duo-R - NOT an RX cos the pad is shit - and get stereo jacks fitted to it. Also I want to change the LED, my old Duo had a funky green one.

My Duo was the first one with the fan mod by D-Lite, and I can testify that my Duo still works flawlessly. Heck, I even played with my Duo for over 6 hours on hot Summer days (80+ degrees Farenheit) and the system performed without a glitch. Sure the fan makes some noice, but it is not worse than the noise made by laptops' or PS2s' fans.

Charles

If the problem doesn't exist in a regular PCE or TG16, it should be possible to fix without using a fan (which I am definitely against).
So what is the difference between the two systems that cause the problem? Perhaps using a sound chip from a TG16 or PCE could defeat it?

Sumez said:

If the problem doesn't exist in a regular PCE or TG16, it should be possible to fix without using a fan (which I am definitely against).
So what is the difference between the two systems that cause the problem? Perhaps using a sound chip from a TG16 or PCE could defeat it?

Click to expand...

I think replacing the sound chip would only be a temporary solution if they were compatible. It's the fact that it's so close to the heat sink that's the problem.

Well, I got some cold spray, to see if I could isolate the most heat affected component(s). No luck. It seems non area specific.

I got a nifty little silent fan. I moved the AV port. I dremeled the opening a bit larger. I installed component video and stereo jacks on the back of the unit. before hooking up the fan, I tested my new AV jacks. Everything is great...

Except that I get muffled sound (the same sound as when it was overheated) ALL THE TIME. I fear the IC that controls the sound is heat damaged.

Ideas?

Let me get this right. You concluded that the location of the sound chip (near the heat sink) is NOT the problem?

What I found was, cold spray did not seem to alleviate the problem. I was hoping to be able to drop the temp of specific component and restore sound, thereby isolating the most heat affected component.

It didn't work. It stayed crackly and quiet. Now it seems it's crackly and quiet at cool temps too. great. I think I need to replace the sound IC. My guess is it's permanently heat damaged.

I now have ANOTHER one of these. This time a TurboDuo.

I've actively cooled the TurboDuo (moved AV, added a fan), and it can now play Hucards for HOURS with no sound issues.

CD music is mostly AWOL though. Sound effects in CD games are fine, but CD music is gone.

I've repaired a lot of systems, and I'm beginning to consider Duo's as temperamental as PS2's.

If there is any info I can share with D-Lite (test results, pics, other useful specifics) they are his for the asking.

I was gonna buy a Duo. I'm beginning to change my mind. If this fix doesn't pan out, I may begin to consider them junk... however...



I have the opportunity to buy a NEW Turbo Duo. Yes, you read that correctly. N E W in box, turned on once. I've seen it, and it is indeed new. I was going to buy it for myself (it's wicked expensive, but the guy who has it owes me big $$$), but running an errand I had an idea.

Perhaps I can use parts from this new flawless Duo to test some things out. For example, I can pop it's laser into this latest TurboDuo with no CD music sound, and VERIFY it's not the laser for example. Perhaps some tests on the new one's components, could reveal the source of sound amp circuit flaws.

The thing is, if this is even useful for reference, I need help deciding the best way to approach and test.

If this new Duo could help in the R&D for this problem, that would be enough to push me over the edge and buy it.

omnedon said:

I now have ANOTHER one of these. This time a TurboDuo.

I've actively cooled the TurboDuo (moved AV, added a fan), and it can now play Hucards for HOURS with no sound issues.

CD music is mostly AWOL though. Sound effects in CD games are fine, but CD music is gone.

I've repaired a lot of systems, and I'm beginning to consider Duo's as temperamental as PS2's.

If there is any info I can share with D-Lite (test results, pics, other useful specifics) they are his for the asking.

I was gonna buy a Duo. I'm beginning to change my mind. If this fix doesn't pan out, I may begin to consider them junk... however...




I have the opportunity to buy a NEW Turbo Duo. Yes, you read that correctly. N E W in box, turned on once. I've seen it, and it is indeed new. I was going to buy it for myself (it's wicked expensive, but the guy who has it owes me big $$$), but running an errand I had an idea.

Perhaps I can use parts from this new flawless Duo to test some things out. For example, I can pop it's laser into this latest TurboDuo with no CD music sound, and VERIFY it's not the laser for example. Perhaps some tests on the new one's components, could reveal the source of sound amp circuit flaws.

The thing is, if this is even useful for reference, I need help deciding the best way to approach and test.

If this new Duo could help in the R&D for this problem, that would be enough to push me over the edge and buy it.

Click to expand...

Aargh! Don't hack up a new Duo just to experiment! We all know that The original model sucks, and we should all go out and buy Duo-R's or RX's. I have a nice Duo-R myself... wanna buy or trade for it? J/K!

BTW, I know i'm a few months too late on this post, did you go though with it? I may have seen that new Duo on eBay before...

Superfamifreak said:

Talk about an understatment. I got rid of my Duo as it had that problem. Gonna get an RGB modded Duo-R - NOT an RX cos the pad is shit - and get stereo jacks fitted to it. Also I want to change the LED, my old Duo had a funky green one.

Click to expand...

Duo R has a red LED, and those pads really are shit.
http://pcenginefx.com/main/dls/TurboTV_PCE_DUO-R.wmv

do these PC Engine Duo's have good games and fun to play?
im interested in buying one later on

neo_X7 said:

Duo R has a red LED

Click to expand...

Yeah, I switched the LED in mine and it looked so much better. So far the only one I've seen with a greed LED

omnedon said:

What I found was, cold spray did not seem to alleviate the problem. I was hoping to be able to drop the temp of specific component and restore sound, thereby isolating the most heat affected component.

Click to expand...

I wouldn't have thought rapidly cooling down a hot component would do it much good!

Folks, I think I have a solution but I do not want to go and post it if it's incorrect.

So.

I need someone to send me a system that:
- has CD music issues
- CD games play fine otherwise
- CD drive doesn't sound like it's grinding all over the place.

The solution, I hope, will be EASY, but will involve opening the Duo and soldering.

Let's just say the reason I need a problematic unit to test is that the last one I had seems to not be so problematic anymore

This needs a bump. My parts DUO, is in a pretty bad way. It gave it's laser optic, and it's AC daughtercard, and it's transport, so it's no good.

I will go through my recieved e-mails, and see what I can come up with. Might be someone out there with one.....

So if the problem is that an IC is in a location with too much heat, what would happen if you were to remove the IC, solder little extension wires to the IC's leads, and solder those to the appropriate lands on the board, effectively moving the chip away from the hot spot? Then wrap the chip in some electrical tape to prevent shorts, like the old Playstation mod chips...