REPAIR GUIDE - TurboDuo: Sound Fix

chop5 · 08/02/2010, 02:14 AM

Just thinking out loud while working on a duo with the sound issue after the cap change:

Didn't know the volume knob effected the av sound thought it was for headphone only. Sound was very crackly at first but when I turned the knob down returned to almost normal. Like an old radio or player with the sound to loud. Could this be the culprit for the final sound issues we have? Not turning it down but that whole region effecting the general sound because its faulty or needs repair. Like could it be cut out or removed all together? Like those audiophiles do with ps1's so all they have is the main audio center without it diverting to other areas on the board.

So far from all the duos Ive worked on I think I know how the whole mess started. The big non smt caps near the heat sink over time and use leaked HUGE amounts of fluid that got under the sound caps and since they are smt and closed off the fluid cant drain or evaporate causing the smt caps to malfunction and causing shorts and rust around the pins making them look black when you pull them off the board. I have found liquid under caps in that area and thought it was fluid from the smt cap itself but its too much. Also this fluid seeps thru the via's and leaks to the bottom of the board causing all kinds of damage. If the fluid can cause shorts and rust under the caps it can do worse to any chip it meets.
The huge caps even tho they leaked fluid that you can swab under them to see it,were checked with a cap meter and were still under acceptable working condition. What worries me is that I have changed alot of those big caps and will more fluid leak again over time?
Perhaps larger and more heat resistant caps are needed.
I need more duos to work on to be sure.

spaceheater · 08/27/2010, 10:57 PM

hey guys! I recently pulled out my Turboduo to play a little Lords of Thunder only to realize my Duo is suffering from popping/fading into no redbook audio issue.

Thanks to this forum, I know what the problem is and how to fix it.

So far I've been looking for someone able to repair these things, but no dice...

I don't have much experience with soldering (as in: none), but having bought myself an iron, a small PCB, and a cap to play around with I've discovered I can actually solder! So I'm considering doing the cap replacement myself. I've got a security bit and opened the system already, its just a matter of building up the confidence to do the replacement.

I do have a question about this tho: is there any special consideration I have to use when buying caps or will any do? I understand the capacitance and voltages, but I was worried about other capacitor ratings like resistance or even if I should stick with using the little smd v-chip capacitors. The reason I'm asking is Radio Shack is a total rip-off on these things (its >$1 a cap), and I want to make sure I order the right thing when buying from an on-line dealer selling something better at a tenth of RS' price.

just to let you know, my next step is asking for advice on how to go about gutting the system to reach the caps, so now's a good time to send some panicked "NO DON'T DO THAT!!1" pms before I potentially ruin my system. If push comes to shove, I'll blog my progress for you guys. I don't have a job, so I have plenty of time.

PigInTheMud · 09/04/2010, 10:53 PM

I would definitely recommend purchasing the caps from mouser.com 8 cents to 30 cents per a capacitor.

Make sure that:
The capacitors are Aluminum Electrolytic Capacitors - Leaded.
The capacitance(most important) and voltage are the same.
The minus side of the capacitor get's soldered onto the minus hole.
Don't let your soldering iron touch anything except the board and the wire parts of the capacitors.
Remove all static from your body by touching something that is metal and grounded before dealing with the board.
Don't wear socks (especially on carpet)
Try to remove oils from your hands.
GET FLUX! It helps so much with soldering things together! http://www.radioshack.com/product/index.jsp?productId=2049774

That's about all that I can think of when soldering video game consoles

BlueBMW · 09/11/2010, 06:42 PM

I did the sound fix on a new / broken duo I got. I tried the two 10uf caps first, but that didnt correct my problem. (left channel quiet, and right channel cutting out randomly) So here's some PCB pron pics of what I found! Sounds works perfectly now!

/capsbefore.jpg
/capsafter.jpg

Duo_R · 11/13/2010, 07:18 PM

OK Charlie or anyone else that knows, I am going to replace out the 4558's found here:

/24284354.jpg

Now my question, are all the 4558's on the Duo boards the same? There are other 4558's on the top of the Duo boards, but they have different codes printed on them. I don't see any reason they should be any different but wanted to see what you guys think.

So far I swapped out the 4558 on the left, but still no ADPCM!

BlueBMW · 11/13/2010, 09:05 PM

As far as I know 4558 is a standard code for that particular chip (its an op amp of some variation right?) the other numbers are probably just batch numbers or serial numbers or mfg numbers.

Duo_R · 11/13/2010, 09:44 PM

update - I replaced the 4558 on the right, and the BU4053BF....and still no ADPCM. I also swapped another cap just in case it was bad (replacement). I gotta say I am not seeing any hope on this one. How about the 4558 near the audio circuit. maybe that one could have gone bad with all the leaking caps? Would that be related to ADPCM somehow?

Quote from: Duo_R on 11/13/2010, 07:18 PMOK Charlie or anyone else that knows, I am going to replace out the 4558's found here:

/24284354.jpg

Now my question, are all the 4558's on the Duo boards the same? There are other 4558's on the top of the Duo boards, but they have different codes printed on them. I don't see any reason they should be any different but wanted to see what you guys think.

So far I swapped out the 4558 on the left, but still no ADPCM!

BlueBMW · 11/13/2010, 09:48 PM

I'll just assume you've done all the caps near the audio circuit yes?

Duo_R · 11/13/2010, 09:54 PM

I kid you not...100% cap replacement. EVERY damn cap!!!

Quote from: BlueBMW on 11/13/2010, 09:48 PMI'll just assume you've done all the caps near the audio circuit yes?

BlueBMW · 11/13/2010, 09:57 PM

Haha, i can see how that could get VERY frustrating then! hmmm... well if there are any donor chips you need that a US Turbo CD mobo might have, let me know I've got a bad TGCD mobo laying around.

Duo_R · 11/14/2010, 09:03 PM

Ok I was talking to Chop last night and he gave me the idea that there might be a bad trace. I took some time and checked the adpcm circuit and discovered that one of the 4558 chips was not grounded....because if a bad trace. After booting up Gates if Thunder....i heard Bonk speak for the first time in a couple years! Now a side effect, for some reason the sound volume is now extremely low. It previously was running low about 40% of normal levels, now it is about 20%. Same if using the headphone Jack. Any theories here? Perhaps the 4558 in the sound circuit has failed? I feel like I am very close to full revival of my Duo that I have had since 1992!!!

Charlie · 01/08/2011, 03:06 AM

Hey,
Shouldn't this topic:
"No sound on right sound channel (ADPCM fixed)"
be made a part of this thread? It seems to be a continuation, or at least a closely related subject.

Or, I could just post the schematic here??

Charlie

Duo_R · 01/08/2011, 03:09 AM

It could but how exactly do you sticky two threads together?

Quote from: Charlie on 01/08/2011, 03:06 AMHey,
Shouldn't this topic:
"No sound on right sound channel (ADPCM fixed)"
be made a part of this thread? It seems to be a continuation, or at least a closely related subject.

Or, I could just post the schematic here??

Charlie

Charlie · 01/08/2011, 08:31 AM

Don't know, but...
I have occasionally seen a post in one thread move to another thread. Can't that same thing be done on in this case? (although it may mean a lot of one-at-a-time message moving). Or just make the second thread a second sticky, and reference one to the other?

But I think that, given the prevalence of audio problems on Duo's, we should make sure that the info, the schematic, and the success here is readily "findable".

Just a thought.
Charlie

Duo_R · 01/08/2011, 01:48 PM

The trouble is when these threads get 20 pages deep, who is going to take the time to go through all this?

Charlie · 01/08/2011, 08:44 PM

The same people, myself included, that go through 2+ years worth of threads to find that one single bit of elusive data they need. That's how I got started here. But I agree that moving 20 pages of posts is a lot of work. Too bad there is not a way to link the two threads. Guess it just means a lot of exercise for the Search Engine.

Charlie

BlueBMW · 01/09/2011, 10:00 AM

Quote from: Charlie on 01/08/2011, 08:44 PMThe same people, myself included, that go through 2+ years worth of threads to find that one single bit of elusive data they need. That's how I got started here. But I agree that moving 20 pages of posts is a lot of work. Too bad there is not a way to link the two threads. Guess it just means a lot of exercise for the Search Engine.
Charlie

Cant you link directly to a post number? Maybe the original poster (if they're still around) could add links to the first post that go directly to the golden nugget posts deeper in the thread.

nat · 01/09/2011, 02:12 PM

I can merge that thread into this one, but the result won't be pretty. The messages are merged chronologically, so, the posts from the other thread will get inserted in between messages from this thread, resulting in total fragmentation of each individual conversation.... If you catch my drift.

Duo_R · 01/09/2011, 02:35 PM

yeah that wouldn't be great. Maybe a reference to the other thread in the first post somehow?

Charlie · 01/10/2011, 06:03 PM

Definitely don't want the chronological screw-up, it would defeat the purpose of making important info readily available.

What if we made this thread itself a sticky, and just referenced each one to the other one?

Charlie

esteban · 01/18/2011, 07:28 AM

I think you figured out the solution:

(1) Revise the topic of the thread(s) to be as informative as possible (and reflect all the topics discussed)
(2) Revise the first post of each thread with a "Table of Contents" as well as a cross-reference to other thread(s).

Now, since D-Lite may not be around to make these edits for this thread, well

I can, however, revise my reply (#2 in this thread) as a desperate, futile attempt to help others.

TANGENT: Just a thought...
Also, if anyone is interested, I'd be happy to host standard html versions of particularly useful/reliable information on my site. It should be preserved for posterity... especially all the images that have only temporary homes.

pixeljunkie · 01/21/2011, 04:00 PM

Quote from: onetunafish on 07/22/2010, 07:09 PMHello all!

I think I might have a similar problem, except with a CD-ROM 2 Unit.

Similar symptoms:

- Cd-rom audio goes silent or out of sync after a while in some games (ie rondo of blood)
- the cd-rom audio quality is really bad, cracks and static noise, even playing music cds
- In one game the sprites don't show up at all (martial champions)
- Every now and then the just a moment seems to go on forever

From what I've read, it might need to replace some caps, clean the laser lens and/or adjust it or even replace the whole cd reader. I couldn't find which caps to replace on the CD-ROM unit, would any body be kind enough to point those out to me? I took a quick glance at it but I didn't see any poped caps or signs of leakage but I'm no expert. Any help is very much appreciated.

Ed

me and a friend are having pretty much the same problems and are equally curious of a solution. Quoting you for emphasis

Keith Courage · 01/29/2011, 05:51 PM

I wanted to post something I have done to fix two duo units with audio problems to help others out. I have repaired two units where changing the caps did not fix the problem. I was getting very distorted sound but head phones were fine. I ended up having to run two wires from the last two caps(positive end) to the solder points on the board for the audio cable. I can't think of what part on the baord actually is bad but this fixed it for me. Picture shown below. Anyone have any idea what part actually went bad? Maybe a tiny resister under the board?/img0142hj8.jpg

Charlie · 01/30/2011, 06:28 PM

You may have a problem here, if those caps are C678 and C679. The positive end of those caps has a DC voltge on it, which is the output of the amps. A short on those pins (caused by something with low impedance connected to the output jack) can very well damage the chips, as well as putting a DC voltage on whatever you have connected to the output jack. You should actually come off the negative side of those caps. But, I notice in your pix that the capacitors are installed with the neg end toward the chips....are you sure you installed the new caps properly, and have not reversed them? If so, you have actually connected to the proper point on the PCB (which means, no, you DON'T have DC on the outputs), but the caps are reversed polarized.

Please double check this.

As for what parts are in that circuit, the abbreviated schematic (including the cap polarity) is available here:
https://www.pcengine-fx.com/forums/index.php?topic=7328.msg153079#msg153079

Charlie

Keith Courage · 01/31/2011, 03:27 AM

From looking at the board the plus side is on the left where my lines are drawn.

Charlie · 01/31/2011, 09:40 AM

I'm not saying you are wrong, just that it SEEMS wrong. I'll have to check my notes.
Thanks for the double check.

Edit: Yup, at first check, it looks like the caps are placed correctly. This means I'll have to go back and check the circuit on the board itself, and maybe edit my schematics to show the caps properly..

As to the actual problem, between the jack and the caps are the coils and the anti-thump circuit. This consists of a set of transistors that turn off the audio when the system is first turned on. Other than that, you may just have a bad connection someplace. I'll check it out and get more details....post later.

Thanks for your patience.

Charlie

Charlie · 02/04/2011, 10:51 PM

Finally figured out what was bugging me. As I said, it SEEMED wrong....because it is. But it has nothing to do with the cap polarity or changing the schematic. You have jumped the output of the headphone amps directly to the AV connector! No wonder you could make the comment that the headphones worked, and that this "fixed" the problem....you connected the AV plug into the working headphone audio. You've completely jumped over the AV amplifier circuitry, which is where the anti-thump and coil circuitry is. Those caps that you have connected to, do NOT (normally) go to the AV output.

Charlie

Keith Courage · 02/05/2011, 03:04 AM

Hmmm, so do you possibly know what part of the board was bad? I changed the two caps I ran the wires from and also the main three caps from the preamp as well. Maybe there were more needing to be changed?

nat · 02/05/2011, 04:30 AM

Did you clean the board before replacing the capacitors? Replacing the capacitors w/o cleaning just stops the bleeding; the next-to-invisible electrolytic gunk that leaked from the old caps is still present on the board, usually shorting things in the process.

Also, there are other capacitors in the audio circuit than the ones you just replaced. See Charlie's schematic for specifics. In addition, there is one way out in the middle of nowhere that isn't obviously connected to the audio, but it is. IIRC it's the one in bottom right corner of the above image, I think it's C512 although it could be C521 or C525. It's been so long I just don't remember, but it seems to me it didn't have anything else near it.

My Duo started in with the "scratchy" sound at one point, and I replaced everything obviously tied in with the audio. Didn't fix it. I started replacing caps one at a time, by the time I'd replaced nearly 75% of all the caps on the board, I replaced that C512 (or whatever it was) and the problem went away. This was almost three years ago, and I haven't had any sound issues since. I don't see C512 anywhere on Charlie's audio schematic, so I'm not sure what role it plays in the audio circuit but it obviously does SOMETHING.

But, again, replacing caps without cleaning the PCB (preferably via a dishwasher cycle) is.... well, think of the Duo like an engine with a bad oil leak. So you fix the oil leak, but don't replace the oil that leaked out prior to repair. The engine still has a hard time because it's missing three quarts of oil. You need to address the residual effect of the problem, not just the problem itself.

If you've already cleaned the board, good on you.... You have another bad capacitor somewhere. Just replace everything mentioned in the schematic and go from there.

Charlie · 02/05/2011, 09:06 AM

C512 is the VCC power cap for U513 (or IC513), the BAFFA RAM.

Charlie

Bernie · 05/08/2011, 04:35 PM

Just to let everyone know, D-Lite is still actively working on systems for people. I have bought a PC engine Duo, which was totally refurbished and have been nothing but pleased. I recently placed an order for a Duo R with him, and should have that one soon. I would also like to add that his prices are awesome. His website is here http://multimods.com/ . Sometimes he takes a bit to respond to emails, but he always gets back to you. Real life has a tendency to get in the way of our hobbies sometimes! lol.

Charlie · 05/26/2011, 06:09 PM

An "out-of-scope" question about the DUO was raised in the "REPAIR GUIDE - TG16 CD/PCE CD laser swap guide " thread, so I put the answer here, and added a reference note there
---------------------------------------
Couldn't find a "Q304", but I did find a "U304"; it's the POR (Power-On Reset) chip, not a regulator. However, it is connected directly to U302, which IS a regulator. It provides power for the ADPCM (U502), the DAC (U201), and the anti-thump, mute, and de-emphesis circuits. I expect that it is the routing of the tracks that caused the bad connection to be physically at the pin on the U304, but electrically U304 is not involved with actually supplying power to anything.

Good catch!
Charlie

thesteve · 05/29/2011, 01:40 PM

Q304 is the power supply for the sound circuits.
its located behind IC505

Charlie · 05/29/2011, 06:40 PM

Aha! Found it. Its a 2SC2412 PNP used as a diode regulator at 8.2VDC. It provides 8VDC VCC for quite a number of IC's in the audio section. This same 8 volts also provides a 4VDC source for other uses.

And, now that I think of it, I am pretty sure I mentioned this transistor before in some post of my own quite a while back! (Charlie slaps forehead with palm - DOH!). Must be getting old; I'll look it up later.

Anyway, thanks!

Charlie

thesteve · 05/30/2011, 02:37 PM

its an NPN used as a current amp for a diode regulator.
the part number looks good.
the circuit provides 8.2v at the base and a current source (about 9V) at the collector.
the transistor provides 7.7V (~8V) at the emitter

Charlie · 05/30/2011, 08:17 PM

NPN it is, the damn "arrow" on the emitter is so small, I can't really see it; probably should have looked up the part number to verify.

Charlie

thesteve · 06/03/2011, 12:14 PM

so i gather you have the schematics and part lists for the DUO?

chop5 · 06/06/2011, 04:10 AM

A sound issue duo me and steve fixed over the last few weeks over chat.

symptoms:
Almost zero sound but if tv is volume on maximum can hear it softly,same for headphones. Some volt meter reads showed it was this op amp chip:

Replaced with near identical op amp chips I got from ebay and sound was restored but static developed and slowly sound will fade in and out depending on the duos mood or me touching the board or touch with toothpick in sensitive area. Much meter and sound probe testing found the trace and some via's going to the new chip were bad. You can see a blackened via in the first picture near pin 5 of ic503. The second bad trace and via was to chip leg 3 of the ic503. bypass was made:

The other wire on chip leg 4 was for ground when we thought the ground trace was bad.
The other side of the board:

The damaged via near pin 5 was fixed with wire and solder to both sides after a bit of scraping with a tiny star screwdriver till shiny copper was seen.
the trace and via of pin 3 was just bypassed shown in second pic. The trace for pin 3 lead to those 2 resistors r321 and r322,it forked into both of them so used a small drop of solder connecting them to the wire like in a T formation.
Static is all gone full sound restored. thank you steve

roflmao · 06/06/2011, 07:25 AM

You guys rock.

mrchuck999 · 07/16/2011, 08:55 PM

Hi Guys: I've been reading this thread today because my USA DUO suddenly has very-soft red-book audio while the chip sounds (guns) are loud and clear. with headphones I can just hear a Music CD play. But a game fire-shots are loud and clear.

This was called problem #2 in an early post. But I never found a clear documented cause-solution. Has any one fixed the "very-quiet" red-book audio (music)? It seems this issue should be caused by a cap dedicated to the CD red-book audio and not the same as over-all low volume.

Thanks for your wisdom. I love this site and all the work from Red-ghost & D-Lite. You know you're awesome!

BlueBMW · 07/16/2011, 11:01 PM

Quote from: mrchuck999 on 07/16/2011, 08:55 PMHi Guys: I've been reading this thread today because my USA DUO suddenly has very-soft red-book audio while the chip sounds (guns) are loud and clear. with headphones I can just hear a Music CD play. But a game fire-shots are loud and clear.

This was called problem #2 in an early post. But I never found a clear documented cause-solution. Has any one fixed the "very-quiet" red-book audio (music)? It seems this issue should be caused by a cap dedicated to the CD red-book audio and not the same as over-all low volume.

Thanks for your wisdom. I love this site and all the work from Red-ghost & D-Lite. You know you're awesome!

At this point, all these Duos are at the age where most if not all the capacitors have started to leak/dry up/ fail. As such, if you're going to open the system to replace any of the caps, it would be prudent to go ahead and replace them all.

thesteve · 07/17/2011, 12:26 AM

i have seen some corroded traces/vias do that as well as bad caps

boliver · 08/04/2011, 07:14 AM

in case its useful to anyone, i had the too quiet cd audio problem with my Duo, and i was able to fix it by replacing the top rightmost 22 cap.

Nagoyan · 08/21/2011, 11:22 PM

Thanks to everyone for all the great info in this thread! My Duo's CD sound recently started to go and replacing the caps seemed to fix the problem. However, while soldering in one of the post-amp caps, one of the solder pads became loose and I'm intermittently losing one of the audio channels. Are there any methods out there I can use to get that pad fixed back in place?

thesteve · 08/22/2011, 12:38 AM

the best fix for a loose pad is to run a wire to the run, or another point it connected to

Nagoyan · 08/22/2011, 01:39 PM

Thanks for your help! I'm pretty new at this sort of thing, so is the run similar to the trace on the PCB? Just to the side of the square-shaped capacitor trace there's a small solder point and I wonder if that's the spot I can connect a wire to from the capacitor terminal. Figure I'd better have a plan B worked out if any more pads go when I replace the rest of the caps in the future.

thesteve · 08/22/2011, 02:44 PM

the term run and trace are interchangable

Nagoyan · 08/22/2011, 04:55 PM

I see. Thanks again for the info!

gamereviewgod · 09/01/2011, 01:11 AM

Thanks for the thread! I fixed my Turbo Express earlier in the week and now my Duo has redbook back... partially. I only have audio out of the right channel. I bought a new AV cord and it's still doing it. I'm assuming it's one of the other caps, but what I can't figure out is how to get the metal plating off. It looks thickly soldered to another component.

Can it just be cut out or does it serve a purpose? I'm assuming the two wires soldered to it are just the grounds, right?

thesteve · 09/01/2011, 01:21 AM

i move the 2 wires to the lower shield and resolder.
the top shield is soldered to the controller port and will need to be heated/unsoldered.
the system runs fine without it, but i reinstall it when done