REPAIR GUIDE - TurboDuo/PC Engine Duo/R/RX: Laser Swap & Adjustment Guide

[void88]

Sup Guys,

i really need your help. after i recaped my duo, the cd unit still played cds with issues. so i bought a new laser and replaced it following this guide. after playing a little bit with the pots, i finnaly got my duo play the cd games almost perfectly without any issues...after some days of not using the duo i just wanted to play some puyo puyo tsu - here the trouble began:

the disc loaded fast as always and at the title screen the music stoped playing. i knew, that my pot settings werent 100% right. i just wanted to try it again and restarted the duo but the disc doesnt move and the laser unit stucked at the very outside. after some trys i managed to move the laser somehow. so i tried to load the game again and same issue...laser moved to the outside and stuck. now i cant get this thing back to the "normal" position.

is there a way to force the laser unit to move back? i spent much money on this duo already, so i want to get it work badly hope someone have a nice advice. thx in advance

[Keith Courage]

Spin the gear/motor manually with your finger to get it free again.

Otherwise if it keeps getting stuck this can sometimes be an issue with CD-R discs. Very rare to see it happen with real CDs.

3rd possibility is that your lens motor is going bad. Typically if it gets stuck with real CDs then the motor is bad. I've had to change a few myself so might want to give that a go.

[void88]

Spin the gear manually with your finger to get it free again.

-_- now that was easy! lol i tried everything except using my fingers

thank you!
this console and this forum is awesome!

[schweaty]

Ok... i need help.  So, I recently picked up a Turbo Duo that wouldn't play CD's.  It wouldnt spin the CD's at all.  I recapped it and cleaned/lubed the rails, but it still wouldn't spin CD's.  I started the first pot adjustment in BlueBMW's process (VR102) and after a small turn counterclockwise, it started spinning immediately.  In fact it read the music CD that was in it.  I played a few tracks (didnt go all the way to the end, which I regret.  reason why in a minute) and popped in Ys I & II.  It started right up, no problem.

I'm thinking "well, that was easy".    I noticed a bit of a whir sound which I attributed to VR103.  Once again (following BB's instructions), i turned the pot a bit counterclockwise and it diminished a lot.  Then things start to go wrong.  About 5 minutes or so after I started the game, the CD started to speed up a lot.  Per BlueBMWs guide, if this happens he says to adjust VR105.  I started adjusting VR105 and it starts to slow down a bit, then the laser goes all the way to the right and snaps back to the center.  At this point, I figure its been going kind of a while at high speed and I dont want to burn it out, so I shut off the console.  After reviewing BB's instructions again, I probably should have cycled through all the tracks on the CD before switching to the game.

Now no matter what I do to the pots I cant get it to read CD's.  They spin for 13 seconds and then I get the dreaded "Please set Disc!" error.  Fast or slow (depending on how i have the pots adjusted), it always stops at 13 seconds and I get the same message.

Any thoughts?

[cjameslv]

Ya you gonna need to redo it all again. I actually used a maker to put a dot on the pcb and the pot when its close so you got a reference point at least. Just be patient. I tweaked mine for a good hour before i was completely satisfied. I noticed different games work differently too, for some reason dragon slayer works even when pots are not dead on but adams family was a nightmare as pots had to be f*cking tuned to a cunt hair accuracy. Make sure your room is dead silent too so you can really hear the laser. Triple test before you put it back together too lol!

[schweaty]

Ya you gonna need to redo it all again. I actually used a maker to put a dot on the pcb and the pot when its close so you got a reference point at least. Just be patient. I tweaked mine for a good hour before i was completely satisfied. I noticed different games work differently too, for some reason dragon slayer works even when pots are not dead on but adams family was a nightmare as pots had to be f*cking tuned to a cunt hair accuracy. Make sure your room is dead silent too so you can really hear the laser. Triple test before you put it back together too lol!

OK.. you inspired me to jump back in.  I believe I am in the sweet spot for VR102 and 104 and probably 103 (not certain because I still cant get it to read CDs).  My point of frustration is VR101.  According to BlueBMW's tips after you get VR102 and 104 in the sweet spot, VR101 comes next.  I interpret the way he wrote it as VR101 adjustment will get it read CD's when its in the right spot.  My problem is, I get no feedback at all when I turn VR101.  It doesn't do anything differently no matter what position its set at.  Its hard to find the sweet spot when you can spin it all the way around without any change in what the laser is doing.

what am i missing here?  how do you know when the laser is just toast?

[Keith Courage]

If V101 doesn't make any change at all then either the V102 is not set incorrectly or the lens gain pot itself is not set correctly.

I set up all my CD lenses by ear.

[schweaty]

If V101 doesn't make any change at all then either the V102 is set incorrectly or the lens gain pot itself is not set correctly.

I set up all my CD lenses by ear.

thanks for the response.  which one is the lens gain? 

[Keith Courage]

lens gain pot is the one on the lens itself. Usually the V102 is the culprit though if you cannot get V101 to make any difference whatsoever.

[SmokeMonster]

Great guide, thanks for writing this up!

The Hop-M3 is only $13.42 shipped through Aliexpress, and it appears to be the exact same part carried everywhere else. Here is the link.

[blueraven]

Thanks! I'm just glad that people are utilizing it! I'll update the thread with this as the Laser source!

[danyetman]

I purchased a PC Engine Duo, knowing that it had no audio.  I'd never gotten my hands on one before, but my best friend was kinda nuts over the TG-16 stuff, and after I bought him a Turbo Everdrive as a birthday gift and watched him go apeshit over it, I kinda got interested myself.

I went through a lot of trouble repairing the Duo, and I have tumbled to some knowledge through a great deal of time, swearing, and frustration that I think others ought to know:


1 - Regardless of how well your Duo works when you get it, replace all caps immediately.  Duos are noted for the poor quality of their caps, and this is not to be understated.  I found that the trace under one of the pre-amp caps was completely destroyed by the cap's failure.  Repairing traces is never a fun thing to do.

2 - When removing the SMT caps, I know a lot of people advocate the 'twist 'em off' method.  Please, for the love of all that is holy, do not do this.  Sure, it's quick, but it only takes one pulled trace to f*ck up an expensive piece of vintage technology for good.  Take your time; use a soldering iron to heat up the legs one at a time and gently pull the heated side up.  Inch each leg up a bit at a time, switching sides as needed, until the cap is free.  It'll take time, but better safe than sorry.

3 - Get a frequency counter if you want to adjust VR105.  It doesn't have to be hugely expensive, but you'll need at least a 10MHz model (preferably 20MHz, just to be safe), and you'll need to know how to use it.  I got an old (looks like 70s or 80s model) counter for $15 off of eBay, and it works a treat.  Definitely gonna save up for a scope next.  VR105 adjusts VCO, which needs to be (ideally)4.3218MHz.  Obviously, the closer you get to this value, the better your Duo will run.  I've managed to get it spot-on, and my games load noticeably more quickly. 

[ul][li]Disconnect the power to your system[/li][li]Connect the counter lead (typically the red lead in a red/black pair) to Pin 1 of Connecter P6[/li][li]Connect the ground lead (black) to Pin 5 of Connector P5[/li][li]Reconnect the power to your system and put a CD (a game works best) on the spindle, and press RUN[/li][li]Using a small screwdriver (ideally plastic), adjust VR105 until you get a consistent 4.3-4.4MHz reading.  It's better to go a little high than to be a little low on the reading, so remember that if you can't get it perfect.[/li][/ul]
4 - One of the problems I encountered that really frustrated me was that CD audio would play decently sometimes, and sometimes it would get scratchy and/or drop out until a new track needed to load.  This is due to either VR101 or VR103.  I recommend going after VR103 first; it's more likely to be your culprit, and unlike VR101, if you take it out of range, it's far less likely to prevent games from loading.  Load up CD game with a sound-test feature (Rondo of Blood is a good choice, because it has an immediately-accessible sound test that will cover the whole range of the CD), and, using Rondo of Blood as an example, select the last music track and play it.  If it crackles or cuts out at any point, use a small plastic screwdriver to make very small movements to VR103.  In my instance, I had to rotate it slightly anti-clockwise, but your mileage may vary. 

5 - One size does not fit all.  I know that there is a rather incomplete Excel matrix of readings off of the trimpots, but when I set my pots to those readings (even the 'average' readings), my Duo kept on failing to load games, playing them with audio errors, or having crazy load times (2-3 minutes to start a game, and sometimes failing to find needed data during an in-game load totally).  Each Duo appears to be a thing unto itself.  Only VR105 requires an absolute value, everything else is...flexible.  This also put me in the awkward position of having to re-determine multiple pots, which brings us to number six...

6 - One pot at a time!  I cannot stress this enough - only work on one pot at a time.  When you think you have that pot correct, test, test again, and test yet again, before going back and testing once more before you even consider moving on to the next pot.  If you fiddle with several things at once, you're far more likely to f*ck things up badly, which is why you should always, always, ALWAYS mark the initial setting with a fine-tipped permanent marker or get AB AC BC multimeter readings, so if you do screw the proverbial pooch in your adjustments, you can return to the original settings and try again.

[blueraven]

Thanks for the additional info on the pot adjustments, and I'm glat you were able to get your Duo back "On the Road"

1 - Regardless of how well your Duo works when you get it, replace all caps immediately.  Duos are noted for the poor quality of their caps, and this is not to be understated.  I found that the trace under one of the pre-amp caps was completely destroyed by the cap's failure.  Repairing traces is never a fun thing to do.

I also apply the "Shotgun Method" to replacing caps. Recapping the duo completely is a good idea, but the soundfix will hold in a pinch if you don't have all the caps on hand. Not for the novice...

2 - When removing the SMT caps, I know a lot of people advocate the 'twist 'em off' method.  Please, for the love of all that is holy, do not do this.  Sure, it's quick, but it only takes one pulled trace to f*ck up an expensive piece of vintage technology for good.  Take your time; use a soldering iron to heat up the legs one at a time and gently pull the heated side up.  Inch each leg up a bit at a time, switching sides as needed, until the cap is free.  It'll take time, but better safe than sorry.

 
Truer words never spoken. While the "don't twist" part may seem obvious to an experienced repairman, this is a really crucial thing that beginners need to understand before really getting into these units. It's like a bull in a china shop. You can rip the hell out of your traces, and cause major headaches having to bridge them which can cause hours of misery and troubleshooting. BE CAREFUL AND DESOLDER ALL TRACES .

3 - Get a frequency counter if you want to adjust VR105. VR105 adjusts VCO, which needs to be (ideally)4.3218MHz.  Obviously, the closer you get to this value, the better your Duo will run.  I've managed to get it spot-on, and my games load noticeably more quickly. 

Yes. I use an Ocilloscope to test the pots, but a frequency counter will also work in a pinch.

4 - One of the problems I encountered that really frustrated me was that CD audio would play decently sometimes, and sometimes it would get scratchy and/or drop out until a new track needed to load.  This is due to either VR101 or VR103.  I recommend going after VR103 first; it's more likely to be your culprit, and unlike VR101, if you take it out of range, it's far less likely to prevent games from loading.  Load up CD game with a sound-test feature (Rondo of Blood is a good choice, because it has an immediately-accessible sound test that will cover the whole range of the CD), and, using Rondo of Blood as an example, select the last music track and play it.  If it crackles or cuts out at any point, use a small plastic screwdriver to make very small movements to VR103.  In my instance, I had to rotate it slightly anti-clockwise, but your mileage may vary. 

An important note, as many people have experienced the audio "cutting out" and have resorted to putting their Duo boards in a dishwasher. I personally have always believed this to be a pot adjustment, and am glad that you are now confirming this, for me at least.

5 - One size does not fit all.  I know that there is a rather incomplete Excel matrix of readings off of the trimpots, but when I set my pots to those readings (even the 'average' readings), my Duo kept on failing to load games, playing them with audio errors, or having crazy load times (2-3 minutes to start a game, and sometimes failing to find needed data during an in-game load totally).  Each Duo appears to be a thing unto itself.  Only VR105 requires an absolute value, everything else is...flexible.  This also put me in the awkward position of having to re-determine multiple pots, which brings us to number six...

I have also experienced Duo's that have had different settings to run purfectly. My original Duo, the ZombiDuo, which has been repaired about 10 times, is missing two of the trim pots. Hence, the Zombiduo. It still plays fine.

6 - One pot at a time!  I cannot stress this enough - only work on one pot at a time.  When you think you have that pot correct, test, test again, and test yet again, before going back and testing once more before you even consider moving on to the next pot.  If you fiddle with several things at once, you're far more likely to f*ck things up badly, which is why you should always, always, ALWAYS mark the initial setting with a fine-tipped permanent marker or get AB AC BC multimeter readings, so if you do screw the proverbial pooch in your adjustments, you can return to the original settings and try again.

YES. NEVER..... Mess with more than one trim pot at a time. It's like screwing up the firing order in your car by putting your plug wires on wrong.

...and Welcome to the forums.

[danyetman]

Thanks, blueraven.  Some follow-up observations I've made, and a question tied into those observations.

I know I must be reading too much into it, but after I got thing dialed-in, I observed, or appeared to observe, that only the games I'd tried to play while it was having difficulties seemed to load quickly and without problem.  This was limited to my burned copies of Rondo of Blood and Cotton.

Naturally, my first assumption was that my setting were 'not quite right', but I found myself hard-pressed to comprehend that games burned at the same rate and with the same device, using high-quality media, would occupy such different ends of the 'ease-of-playability' spectrum.

I threw in Langrisser, and, out of frustration, simply allowed it to load for as long as it took.  The laser seek went back and forth for quite some time, and then...it loaded!  In shock, I turned it off, and turned it back on.  This time, it loaded faster.  I then started going through different games that I had burned but which had not been able to load.  Faussete Amour, Ys I&II, Ys III, Ys IV...it appeared that the more I attempted to play them, the easier time my Duo had of actually succeeding in playing them.

If the technology were not so limited and antiquated, I would almost believe that the Duo was self-calibrating itself, as it had only been exposed to two games in the weeks previous, and had suddenly had a large selection of very different games in Native English, Patched English, and Unpatched Japanese formats.  I have difficulty in accepting this, but the results appear to speak for themselves.

My question is this:  Is the Duo capable of self-calibration?  Or am I simply witnessing the metaphorical jackalope of the PC Engine world?

[blueraven]

Thanks, blueraven.  Some follow-up observations I've made, and a question tied into those observations.

No Problem, glad to share and help

I know I must be reading too much into it, but after I got thing dialed-in, I observed, or appeared to observe, that only the games I'd tried to play while it was having difficulties seemed to load quickly and without problem.  This was limited to my burned copies of Rondo of Blood and Cotton.

Some Duo's have traditionally had problems with burned CD's "Out Of The Box", but I have had reports of some people playing burned games with slightly extended load times.... I will get into that in a minute. I have one Duo that may have been "Adjusted" during the old TurboList days, as it plays burned CD's seamlessly, but has an extended load time across the board, with both original and burned games.

Naturally, my first assumption was that my setting were 'not quite right', but I found myself hard-pressed to comprehend that games burned at the same rate and with the same device, using high-quality media, would occupy such different ends of the 'ease-of-playability' spectrum.

Your assumptions are correct. From my experience, using a high-end CDR (Like a Black Memorex, Taiyo Yuden, or Mobile Fidelity Sound Lab 24K Gold) burned as a direct copy or 1:1 ratio will work best for preserving the quality of game, and will be less likely to data-bleed in the first few years. I still have a Taiyo Yuden copy of Coryoon that is burned from about 2003, and for some strange reason it still works. It has something to do with what is written during the copy process, I think, because I have had different luck with different burners. It may come down to your hardware, but I can't conform this. An original will ALWAYS work better than a CDR, but you can adjust the pots, supposedly to make burned games work more seamlessly with your Duo.

I threw in Langrisser, and, out of frustration, simply allowed it to load for as long as it took.  The laser seek went back and forth for quite some time, and then...it loaded!  In shock, I turned it off, and turned it back on.  This time, it loaded faster.  I then started going through different games that I had burned but which had not been able to load.  Faussete Amour, Ys I&II, Ys III, Ys IV...it appeared that the more I attempted to play them, the easier time my Duo had of actually succeeding in playing them.

If this were a Turbo-CD system, I would say that you have a gear issue. Seeing as this is with a Duo, I would put the shortened load time down to the pot adjustments you made. About 12-15 years ago, there was a modder (I forget his name, but Duo_R or D-Lite got a duo from him and reported this to me back in 2008 or 2009) who could "adjust" you duo for about $35-50 so that it would play burned games flawlessly. How this was done remained a mystery on these forums until BlueBMW got into the trim pot adjustments down around the time I created this thread. We concluded that the adjustments were made to the trim pots to get the burned games to work, and thusly incorporated the the trim pot adjustment guide with the "At Your Own Risk" warning. I'm glad your Duo is functional and improving from this information.

If the technology were not so limited and antiquated, I would almost believe that the Duo was self-calibrating itself, as it had only been exposed to two games in the weeks previous, and had suddenly had a large selection of very different games in Native English, Patched English, and Unpatched Japanese formats.  I have difficulty in accepting this, but the results appear to speak for themselves.

This is 23 year old technology at this point. I'd be hard pressed to believe that the Duo has a mind of its own, but it is possible. oBey has weird gremlins like that. f you leave it alone for a day or so, does it still "warm up" or was that just a one time thing? It could have been that the Duo "came into calibration" after you adjusted the trim pots, and it reacted to it's new settings.

My question is this:  Is the Duo capable of self-calibration?  Or am I simply witnessing the metaphorical jackalope of the PC Engine world?

I think what you saw was you Duo "settling in" to the new parameters you set when adjusting the pots. I'll put the question to the other techies. Thoughts?

All the best with keeping your Duo on the road.