PCE/Turbo Duo sound cut out - A REAL fix perhaps?

[omnedon]

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?

[FABombjoy]

Has anybody tried to isolate the affected circuits with can of cooling spray?

[omnedon]

*sound of omnedon's feet running, door slamming, and tires squealing, on the way to Future-Active for some cooling spray*

LOL

I guess I should get some. It would make testing easier. In theory, I could try to isolate the most 'heat affected' component that way.

/slaps head

[rbudrick]

If you have a capacitor tester, you could also isolate it this way. But I think you have the right idea, it sure sounds like a capacitor is going.

If you put on your infra red visor you should be able to see where it is hottest...oh, never mind...playing too much Metroid Prime...

-Rob

[omnedon]

I'll bring my Digi-Cam to Future active, so when I ask the clerk for some cold spray, and an infra red visor, I can take a picture.

LOL

haven't had a chance to make a run to the elctronics shop. I'm getting excited about this. If it's as easy as moving some caps... wooot! A fix for the ages!

[leonk]

Let me try and take a stab at it.

When it comes to heat problems, not much can be done without going frankenstein on the electronic device you're working with.

The way I approach heat problems is I realize that a lot of R&D has went into making the electronic device (be it an XBOX or a Satellite Receiver that cuts out from heat) and I realize that during R&D they ran it for weeks w/o turning it off.

My point? Don't change the electronic device. Change the way you use it. For example, to eliminate the video cutouts from my sat receiver, I moved it out of the entertainment unit and put it on top of it!

So just see if the problem goes away if the system is in an open airaited spot.

[DogP]

I personally doubt the problem is with the caps... they seem to withstand heat pretty well (most standard caps are rated to 105 degrees C, which is over the boiling point of water). I'd definately get a can of freeze spray and try cooling components (chips and transistors are usually most affected by the heat, which is why those components usually get heat sinks). It's possible that moving the caps would allow better airflow and allow it to cool better, but you have to be careful when moving caps because if you put too long of a wire, you lose some of the effectiveness of the cap.

IMO, I'd try cooling the amp, as these are usually what gets really hot and fails. Also, is there a volume control on the system itself? If there is, you should turn that down and use more volume on your TV (or maybe the modification should be to decrease the amplification). Maybe check the voltage to the amp too.

DogP

[D-Lite]

omnedon, I'm following your posts all around posting this same thing, so no need to read the whole thing.....

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 ;)

[omnedon]

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]

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...


EDIT:

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.

[gcl1984]

I was wonderring, wouldn't it be easier to move the two lm340t's to a little board outside the duo.They would get better cooling and wouldn't heat anything else up.
What are they used for?Do they control Vcc?
I have a duo that is a bit tempermental.Could anyone point me in the direction of some repair info? :/