PC-Engine Duo-RX CD-Rom Issues (Looking for Advice on how to repair)

[SkyeWelse]

Hi everyone!

Glad to see that this forum is still alive and kicking! It's been awhile and I finally had some time in the last few weeks to start really making some progress on hooking up some of my older consoles. I had been using a Duo RX for years without any issues and all of sudden I'm getting that "Set Disc Error", that from what I'm reading seems to be like a general hardware error for pretty much anything having to do with the CD-Rom.

I've seen some other posts here with similar issues and one member (Joe) said he was able to fix his after his PC-Engine had been recapped. From what I've been reading, a recap can sometimes result in needing to adjust the potentiometers a bit with VR102 usually being the main culprit in most cases.

That's kind of what I wanted to try to play around with first before I start taking things apart from the actual cd-rom/laser assembly. I'm a novice when it come to electronics and a bit worse when it comes to the mechanical stuff... ended up breaking the plastic gears in my famicom disk system for instance, so would prefer to stay in my beginner wheelhouse first.

So the symptoms I've been getting outside of the Set Disc error is that the laser will recalibrate and move to the left to attempt to read the inner data layer of the CD. It will spin the disc for a second, then stop and the laser will move up and down (not left or right) just a bit in an attempt to read the disc. When it gives up the process, it will spin the disc one more time for about a second and then stop.



What I thought I might try first was adjusting the pots, and saw a great guide on the forums here that I was attempting to follow:

https://www.pcengine-fx.com/forums/index.php?topic=8926.0

Specifically, I was hoping to try reading the voltage (starting with VR102) of A to B and B to C and C to A, like this guide says:

vr101:AB=12.33 AC=10.65 BC=19.55
vr102:AB=7.89 AC=8.11 BC=11.28
vr103:AB=7.25 AC=7.14 BC=18.46
vr105:AB=0.38 AC=0.00 BC=0.38

But in my case, I'm not getting any where near a DC voltage reading of 7v to 11v, I'm getting like a 2.22v or maybe 2.03v when I adjust the pot a bit. If those values from that guide are showing that they should be much higher voltages, then that makes me think that somewhere along the lines, perhaps a capacitor or two are no longer working as they should and not outputting the proper voltage. The caps at a glance look fine... the PSU is an original one, rated for 9v, but is actually outputting around 13v when I tested it. After it runs through the voltage regulators on the board, I think it goes to around 4v?

I guess I'm just wondering if I'm reading that guide correctly and I in fact should be seeing higher voltages there. I was surprised a bit because it seems like with vr103, the B to C test should be something around 18v and that seemed a bit high considering the PSU being uses is around 9v to 13v.

I was wondering if you did a voltage test on your pots and if you saw something different than what I'm seeing currently. I'm trying to figure out if I should just get a cap kit from Console 5 and just work on replacing all the caps first and maybe that might solve the problem or get me closer?

If you or anyone else has any advice for me or confirmations on what my next steps should be, I would greatly appreciate it. Thanks for reading!

-SkyeWelse

[NightWolve]

Hey Tom, thanks for stopping by!

I'll forward this to @Keith Courage when I get a chance.

[SkyeWelse]

Thanks NW! I appreciate that. A lot of great guides here, just mainly wanted to see if I'm on the right path with reading those pot voltages. I did take the board out of the case and at least I don't see any leaking caps. Just trying to figure out if it's worth recapping as a first step or if there's more diagnosis I can try before I go that route. I've certiainly recapped boards before, but I wouldn't say I'm great at it and SMDs give me some troubles.

-SkyeWelse

[Keith Courage]

Don't bother with a Recap! DUO-R and RX systems never need it. The only Capacitors that are sometimes known to fail are the 2 1000UF capacitors right by the 7805 voltage regulators(big heat sinks).

It's the Black DUO systems that get faulty capacitors.

The issue with your DUO is probabaly a weak/bad lens. Lots of times you can just adjust the V102 potentiometer to get it reading again but sometimes replacement is needed.

Also, check to make sure all wires to the lens are good. Lots of times the Red or white wires can short out from movement overtime.

[SkyeWelse]

Thanks Keith! I appreciate the advice. I took a look at the two black 16v 1000uf caps that are closest to the regulators and I'm getting roughly 12.45v in both of them so yeah, I think you're right in those caps seem like they are operating fine. I'm still puzzled a bit with the guide I linked to above suggesting the the read outs of the pots ABC measurements for the RX aren't anywhere close voltage-wise to what I'm seeing when I test, so I'm wondering how I would best calibrate all the pots if the voltages aren't matching up.

I have checked the continuity of the wires going to the lens and can confirm that both connectors seem to show good connectivity for the red and white wires and there isn't a short from what I can tell, at least not from those wired connections at least.

I guess that would just leave the lens replacement as the next logical step. I'll check the guides here to see which lens is recommended for replacement, but if there is one more recently available that is easy to install I'd love to know about it! I took a look at the lens that is there and it looks like I can mess it up if I don't know what I'm doing, so definitely want to follow a guide there if possible.

By the way, if for some reason I can't get this repaired myself, who all do you recommend to fix these up? Is someone offering that as as a service these days who is pretty well known and trusted?

Thanks again for your reply!

-SkyeWelse

[Keith Courage]

I actively do repairs and mods for these systems. You can send my way if you don't want to fix yourself.

An HOP-M3 lens is what you'll need. Unfortunately it can be hit and miss with replacements found online. Fortunately all sellers guarantee the lenses sold. So if you get a bad one in the mail, they will just send you another one. I can't necessaily recommend one seller over another.

I typically order off of Aliexpress but there are many options on ebay as well.

[SkyeWelse]

Great! Thanks for the information, Keith. I'll definitely try to order a new lens soon and consider giving the install a try. If it looks like too much I'll send you a direct message and maybe we can work something out. I'm curious though what you would consider a good price. I see that they are kind of all over the place. Some places have them for under $20 including shipping, but some have them go all the way to $45. Then there are some that have full replacement enclosures that looks pretty much plug and play for about $50 to $65. For a few bucks more.... maybe that's the way to go? Hmm.

I can usually handle soldering well enough as far caps and the like, but SMDs are a little troublesome for me and certainly I'm not familiar with CD-Roms. I have a non-working CD-Rom in my FM Towns II MA model with no idea how to really fix it, so I've never seen the system it in action before sadly even though it turns on and displays a picture...

Thanks for your help.

-SkyeWelse 

[Keith Courage]

Don't bother with the entire lens assembly. They aren't an exact drop in replacement as the rubber mounts are different and the White/black plastic cover doesn't fit on them correctly.

The only reason to order a full assembly would be if you needed any replacement motors or gear.

Just get one of the $20 ones. I've tried some of the more expensive options and they don't appear to have any difference in quality.

[SkyeWelse]

Thanks Keith, I found one for around $15 bucks so I'm going to take a shot with that one and we'll see what happens when it arrives! Might be awhile before I post again as I'm sure it will take some time to come from China. Plenty of time to read up and familiarize myself with the process or any other tools I may need. Looks like one guide said I'll need some kind of smaller sized security bit, so I'll see about getting one of those as well.

Thanks again for your help and advice!

-SkyeWelse

[Keith Courage]

The security bit is only needed to open up the console. Otherwise there is nothing inside a duo that requires one.

[SkyeWelse]

Oh I see, gotcha, yeah in my case maybe mine had been opened before because I only have regular screws. I've got a couple of security bits for opening up the NES/ AV Famicom, but yeah I guess I won't need that then. Thanks!

-SkyeWelse

[Keith Courage]

Something else I just thought of after looking at your first pic. If you are testing a CD with the case lid off, you need to take the magnet out of the CD lid and put it on your disc so it doesn't slip when the drive spins up.

[SkyeWelse]

Hey Keith,

Thank you very much for all of the guidance and help with this problem and thank you too for suggesting the magnet being used to hold down the disc. That was driving me a little crazy for while when the disc would spin and sometimes it would be read and other times it wouldn't even when I wouldn't touch anything.

So the new laser arrived and it defintiely was the culprit like you said. As soon as I put it in I started having more success with the cd spinning and attempting to be read. It still wasn't reading anything at first so I started adjusting the potentiometers starting v102 and sure enough, I was able to start reading the pressed cd-rom of FX Unit Yuki. I don't know what it is about FX-Unit Yuki, maybe the fact that the cd was newer but I have not had really issues getting the game to at least start up, even if some of the music tracks were a bit off and in need of further calibrations. Thankfully that cd also has a soundtest which really helped me with adjusting v105 and v103 to get all the tracks to play across the span of the disc.

At first I encountered issues getting other pressed cds to work, both US and Japan regions but eventually I got the pots positioned using that guide by BlueBMW (by ear guide) and eventually all pressed or official cds worked just fine. CD-Rs were another story altogether as my cd-r of FX Unit Yuki Demo and my CD-Rs of Dawn of Ys Translated with the English Dub that used to work before were not working initially. Using that guide and understanding the pots and what they do, I was able to kind of tweak one by one until I could eventually cut the system on, start the disc and not have to wait much time for it load to the black screen and then ultimately the title screen.

So hopefully, with any luck, those settings will stay that way and I'll close everything up in the case again soon and start playing some PCE again!



I'm also looking forward to any good games have been released since FX-Unit Yuki that I should check out or any new noteworthy translation projects that have come out since then as I've not really been paying attention to the scene, for example did the Kaze no Xanadu I&II trans/english dub ever come out?

Anyhow, thank you for your help and it's good to get this working again!

-SkyeWelse

[NightWolve]

I'm also looking forward to any good games that have been released since FX-Unit Yuki I should check out or any new noteworthy translation projects that have come out since then as I've not really been paying attention to the scene, for example did the Kaze no Xanadu I&II trans/english dub ever come out?

Same story with the Legend of Xanadu projects unfortunately: SamIAm got too busy with a growing family so that hobby work was put on indefinite hold/hibernation... The FX-Unit Yuki team however is working on a new PCE homebrew I noted in the forum news/chat modules.

Anyway, congrats on fixing your CD laser, that's the type of DIY success stories I like to see!