REPAIR GUIDE - TurboDuo/PC Engine Duo: Total capacitor replacement chart

[nick3092]

Right below the laser and above a pair of 22uF caps. 

Wow, do I feel like an idiot.  Between it being under the wires and the plastic holding the wires down, I never physically saw it on the board.  And it just blended into the picture.  Well, it works as is.  But considering I replaced all the other caps, and I have the 3.3 sitting here, I might as well replace it.  Eh, this weekend.

[Red Ghost]

Make sure to note the voltage of that cap when you remove the old one. From what I recall (and will update as soon as I can) the voltage on that cap was really high. Like 50V.

[nick3092]

Yeah, it says:

3.3
50
20

on the top.  Luckily the 3.3 I ordered was a 50.

[Red Ghost]

Yeah, it says:

3.3
50
20

on the top.  Luckily the 3.3 I ordered was a 50.

Great! You should be all set then.

[Duo_R]

is the 3.3 the memory backup "battery" cap?

[nat]

is the 3.3 the memory backup "battery" cap?

Negative. The backup battery is the component directly to the right of the yellow-circled component in the second pic.

[Red Ghost]

Did a little update. Tried to clean the post up a bit and make the 1st chart a bit nicer. Will add the rest of the voltage ratings and other things after New Years. Enjoy

[agt_dale_cooper]

While I'm not one to reengineer 'works of art', isn't the new background rougher on the color cartridge?
Is plain white out of the question?
Color is REQUIRED for this printout, but really only for the board itself where the different color marks are...perhaps this brilliant new blue could take the place of the grey 3.3V that another member already commented he didn't see..perhaps this new hue would be more appropriate there?

For whatever it's worth, I disagree with the watermarking issue...to an extent.  Yours was originally rather large, but is now easily cropped out.  How about a nice little line along the space/trace lines above the HuCard slot?  For more style points, take out the "L31-XX-2804B" and replace with text/watermark of your choice...."All your PC Engine are belong to www.pcenginefx.com!"  HAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!!!!!!
It'll go with my t-shirt:  http://www.thinkgeek.com/tshirts-apparel/unisex/gaming/3777/?cpg=ab

All comments herein intended as non-insulting / constructive... 

Enjoy your time away for the holidays, I hope to have more progress on this sound issue by the time you return, I've another JAP unit on it's way here, gonna compare apples and apples....

[Red Ghost]

isn't the new background rougher on the color cartridge?
Is plain white out of the question?
Color is REQUIRED for this printout

Good point. I hadn't thought about printing it out. I usually just reference these off my computer. I've made the change.

the watermarking issue...

I put the name/website at the bottom so that people who are bothered by it can remove it for printing. However, there are multiple water marks in the image. Only one of which I think is even distinguishable to the eye. I set it up this way so that hopefully most people will be happy with it, including myself.

Enjoy your time away for the holidays, I hope to have more progress on this sound issue by the time you return, I've another JAP unit on it's way here, gonna compare apples and apples....

Thanks, and good luck.

[Zeon]

Edit: Nevermind, it's .047 farads, not microfarads, which is 47000 microfarads, which is pretty big for a cap for being in a duo. I'll have to order some.

There is an odd type cap I have circled in red in the picture. I don't know what type it is specifically it looks like it is some special type as NEC is silk screened on it. It might be a high quality cap used to filter the audio. I can tell you it is a 5.5 volt polarized .047 microfarad cap (it says 473 on it, the 3 being the decimal place), but beyond that I don't know anything else about it. Duo says on his duo-r there is a rather large electrolytic cap in it's place.

I only realized this was a cap today as I didn't look at it to closely, dismissing it as something else. When I get back to my apartment tomorrow, I will try replacing it with a electrolytic cap with similar specs and see if it fixes or improves the audio issues on the duo I am repairing.

[Duo_R]

yup, I think we have discovered another cap. Is this the one that Nat mentioned a while back? I never assumed this was a cap until I saw my JP Duo with a large cap right in the same spot. Everything parts wise looks identical from JP Duo to US Duo so that part stuck out like a sore thumb. The US Duo has this Monolith rectangle looking thing that I guess IS a cap.

Here is a picture of the cap on the PC Engine Duo (big green cap):



I will take another snap of the two Duo's that are side by side. I have been running / testing games with the covers off, I kinda feel like DJ Turbo......

[nat]

That's the BRAM battery.

[Zeon]

That's the BRAM battery.

Haha makes perfect sense, big cap for longer retention of save data. Don't know why I didn't think of that, well back to the drawing board, my next suspect is the M51131L which is a 2-Channel Electronic Volume Balance ic. Beyond that and the oki chips, and those small amps, i am stumped. My reasoning is suspecting the M51131L is that one of the audio caps that we typically replace in repairing duos, it dangerously close to the M51131L. When the cap leaks it's possible that electrolytic gets around the pins of the M51131L and shorts something out damaging it. Anyone know of a place where I can get a replacement?

[pceslayer]

Does anybody know which caps are responsible for the operation of the laser?

I have an odd issue where my Duo won't reliably read tracks past a certain portion of the disc.

I'm not really sure its an issue with the caps at all, but figured i'd start here.

[nat]

Your laser needs to be tuned. There are four or five pots on the Duo motherboard that control intensity, sensitivity, focus, etc. Calibration drifts over time.