REPAIR GUIDE - PCE|TurboDuo/R/RX: CD Laser Swap & Adjustment Guide

[mikebrandt]

Still no success for now  I ordered an other HOP-M3 module just in case... Steve, if you happen to find points on duo pcb where i could plug my oscilloscope to see what's going on, that would be great!

Cheers,
   Mike

[fraggore]

Adjusting the Pots:

Advanced Users/Modders only! (unless you really want to risk it...)

BEFORE YOU TOUCH ANY POTS, USE A THIN PERMANENT MARKER TO MARK EACH POT'S ORIENTATION.

Tips: The main issue is breaking a pot, or putting it so out of whack the CD player won't read discs at all. Be very gentle, and go SLOWLY when rotating the screwdriver, trying for just a few degrees (out of 360) at a time. This is 20 year-old technology and electrolytic fluid my have weakened the traces. VR102 is the place to start. Please reference BMW's photo below before proceeding.
...
Hopefully this helps, any suggestions are appreciated!

Thanks mate for the guide with a little patience i got mine working after a full recap and laser change thanks again.

[thesteve]

i may have some sig names wrong, but scope cal DUO-RX
duo p7
pin
1 4.5V square
2 5V square
3 FE VR103
4 TE VR101  (set to min)
5 RF 30mV
6 trk
7 focus

[JohnnyPhantom]

Hmm, not sure if I'm doing something wrong, but on my Pots, I measured all A-B connections with my multimeter and get the right readings, however nothing else matches (A-C B-C) what am I doing wrong?

[thesteve]

here is the best info on scope points (I, may revise/add to)
duo p7
pin
1 4.5V square
2 5V square
3 FE VR103
4 TE VR101  (set to min)
5
6
7


DUO P5 (confirmed correct)

1
2 RF
3 TE
4
5 ASY
6 GND

[King_Vidiot]

Hey guys, I want to finally get my Turbo Duo working right.  As of now, the duo will play CD games about 30% of the time depending on the game.  Many times it just spins and spins and doesnt load the game.  Does this mean I should definitely replace the laser? Or if I open up the duo could it be just an adjustment issue or something?  

If I do need to replace it, where can I get a replacement laser?  

Thanks

[thesteve]

for starters, clean the tracks and gears
regrease and retest

[PCEngineHell]

I thought I would add my two cents on this. After recapping this latest Duo I acquired, I was getting cd audio cut outs, laser whine, etc. Looking over the gears, they did have the tiniest bits of plastic crud built up, which was causing the gears to jam while I was testing. I stripped the gears of all grease, and cleaned the gear teeth with a tooth brush, then re-lubed everything. After all of this I had the nasty whine still, and also, random audio cut outs. I noticed the whine got worse, as did the audio cut outs, the further down the disc the laser had to read. The makes sense, as the laser has to bob and adjust focus more the further down it reads due to disc warping and spin rate adjustments, etc, and not being calibrated right will cause it to lose focus during its eye bobbing up and down.

Unfortunately I don't have a normal pressed music cd that can go the full 80 mins, but I did have a Star Wars Return of the Jedi 2 disc soundtrack set, which happens to have both disc clock in at over 70 mins at least, which I was able to use for helping with adjustments.

Adjustment to any of the pots on the TurboDuo's gave no positive results what so ever. In the end it amounted to me needing to simply adjust the pot on the laser itself. I would play a track or two, if whine persisted, shut down, adjust the pot a tad, turn the unit back on, and test again on the same tracks. No whine, good, no skipping, even better. Move on to the next couple of tracks, rinse and repeat. Eventually I got the whine gone completely from this cd set, and all games mainly except one. It was still present during Image Fight II, especially during the last stage music track, which I would get whine and music cut outs. Due to this, it still needed some slight adjustment still.

Once the laser whine was eliminated from this, it seems everything was about as perfect as can be. No more audio cut outs during the stages music play back (by now it should be no surprise why I beat Image Fight II, I was using it to calibrate the laser, causing me to play the game over and over and over again).  As is, everything seems good to go. I dont play cd-rs on old hardware, so I cant comment on how well they would play back, but so far every cd game I own has been going strong since final adjustments.

Some recommendations I would suggest off hand that I know could be helpful in thorough laser adjustment is the following:
Image Fight II (you can pause the game during gameplay and the music will continue to play, and loop, so it helps to let it sit and loop a track for a good 20-30 mins so you know it can play it without skipping/cutting out)
any pressed music cd that meets or passes the 72 min mark
random games that you can get to play to near the end of the disc music wise (Winds of Thunder/Lords of Thunder is a good candidate for this with its audio tracks being accessible from the option screen and its 19th track being near the end of the disc)

After all of that, its good to just do general gameplay testing. You might run into a oddball game that wasn't pressed as perfect as it could have been, so it might cause a skip or something, making you pop the system back open for a last calibration. The more titles you try out after general calibration, the better off you will be.


Anyway, like I said, just my two cents based on the recent experience. This was not a issue I had run into before with other systems on laser swaps, so, meh, more work and all, but whatever, life goes on.


EDIT: To add to this post, I'd also like to add that after adjusting the lasers pot and eliminating whine, if you are still getting skips past like the 72 min mark on a cd, then I would definitely try slight adjustments to pot VR101. That would be the last thing I would go to adjust focus though, not the first, personally. It also helps to speed things up on your final adjustments if you fast forward through the last 10 mins of the music cd you are using for testing a few times (you may want to alternate between FF'ing through the last 10 mins and also the first 10 mins to make sure its fine tuned on both ends of the spectrum). If still not focusing right, the laser will skip during the fast forward and you will get noise out of the speaker confirming this. You can also set the time counter to total time remaining to help spot the skips easier also just in case. Once you have eliminated these final skips and any laser whine you should be 100 percent set I would think.

[abraXXious]

Hey guys,

this is my first post in this forum, but I thought it might help anyone attempting to get their Duo/Dou R/Dou RX reading audio soundtracks properly.

Recently I replaced the Hop3 laser lens modules in two Pc Engine Duo Rs and a Pc Engine Duo RX. After replacing the lasers I found that games loaded perfectly but that the cd audio sound tracks would either not play at all, or would start playing and cut out abruptly after a random time period (usually between 5 and 30 seconds).

I assumed this was to do with the 5 resistor pots on the Duo R/RX motherboard, so I followed this guide. I tried measuring the resistance values specified but found my units were very different to the values listed - so different in fact that even by turning the pots to their extreme positions would not bring the resistance value anywhere near the listed values.

So, I tried using the "By Ear" approach. The weird thing is that when I tune the pots on all three Pc Engine Duo machines to the quietest settings, nothing will load any more!

Luckily I had marked the original positions of the pots with a sharpie pen.

After spending 3 nights playing constantly with the pots etc I was on the verge of giving up when I noticed the resistor pot on the hop 3 laser module itself. I thought, "why not?" I had tried everything else.

The pot had a drop of resin holding it in its original position, so it took a firm grip with a philips screwdrive to move the pot. I moved it about 5 degrees clockwise  - all of a sudden everything was working perfectly - including all audio soundtracks and even CD-Rs.

I replicated this adjustment to the two other Pc Engine Duos - same result!

At firsst I thought the caps on the motherboards were getting sad and so the adjustment on the laser was compensating for the reduced current being provided by the caps, however on close inspection of all 3 motherboards I can safely say there is NO leaking of ANY caps at all, and since they now run absolutely perfectly I can only assume that the replacement lasers are adjusted in a such a way that the Pc Engine does not like.

I just thought I would share this experience with everyone in case anyone else is experiencing the same problems tuning the Pc Engine Duo.

Hope this helps.

[thesteve]

sadly the lasers are now made by several knock-off manufacturers.
they all set them differently, and mostly wrong.
yours were set too low, but ive gotten them set so high they wouldnt read CDR at all

[Nec.Game.head]

This repair guide rocks! It took me a few days to finally feel comfortable enough to start messing around with the pots on my Duo-r and it totally worked .. No more losing audio at random times .. And it even reads the few cheap quality cdr's I have even better then before .. All it seemed to really come down to is once you find your audio cut out points clockwise and counter clockwise you place a piece of tape on both sides of were it cuts out your audio and center your pot right in the middle of that .. You can always fine tune it after that until you feel satisfied with your adjustment results .. Just be sure to make a tiny little mark on your pots and the board before starting your adjustments, so that you know exactly where they were positioned originally just to be on the safe side .. Thanks a million you guys for contributing all this useful information!

[rCadeGaming]

Just wanted to say that I used this guide yesterday and got great results as well.  The only thing is, while adjusting VR101-105 perfected some games, others still had problems until adjusting the pot on the side of the laser, as others have mentioned.  More info here:

https://www.pcengine-fx.com/forums/index.php?topic=14064.msg281184#msg281184

[Chester77]

My Duo R recently stopped reading all CD media types.

I have taken measurements at the pots and tried adjusting them to settings specified in this thread but I cannot get even close to the values specified here.

as an example:

VR101:
GOAL:   AB=12.33 AC=10.65 BC=19.55
ACTUAL:AB=12.0 AC=10.2 BC=10.5

As you can see the BC value is only half of the value we are expecting.
I can adjust the pot to get somewhere around 20 for BC but then the values for AB and AC are all out of whack.
I worked on it for hours and could not dial in the right settings.

I have ordered a new laser unit because it can't hurt to have a new laser but I don't think that will solve my problem.

The power supply is the original A/C power supply that came with the system.

Could bad caps be the cause of this? I don't see any obvious issue with the caps.

If it is believed to be the caps... how do I test them and where do I find replacements?

Thanks!

[thesteve]

caps are unlikely
yours has a different value pot most likely
your best start point is set how it was working
look for issues with binding first, before trying to adjust pots

[Chester77]

caps are unlikely
yours has a different value pot most likely
your best start point is set how it was working
look for issues with binding first, before trying to adjust pots

Thanks for the reply.

If I position the unit all the way to the right before power on the unit works it's way inward with no visible impedance after applying power.

I was able to adjust the pots to the pot where the disc spun the entire time between "press run!" and "set disc" but it never actually accepted a disc.

I will try a new laser unit when it arrives.

[IrishNinja]

hey all! 
i bought a Duo-R off a popular ebay seller but am also running into the "CHECK DISC" or whatever error, i bought a power supply from retro game cave so it's not that...seller says i need to tighten a resistor and linked to this guide nifty.com/moremaco/slv.htm, even sent me a minus screwdriver which was really cool.  a search brought me to this helpful guide as well.

problem is, VR102 looks...damaged ?  i don't see how said screwdriver will catch, i'm grabbing a # 0 phillips head tomorrow but i'm hoping this pic illustrates the problem:

what can i do here?  it showed up like this and i'm not certain if i have enough on the side to maybe catch with a pair of needle nose pliers and adjust that way, or should i try to remove it & replace with something else (assuming that's even an option)? or is it supposed to look like that?  appreciate any help i can get here. 

it's tricky too cause that guide says i cant unplug the short cable on the right side, but there's a short one on the left too that connects to the region switch installed on the hucard slot, i don't think i can remove that either so we're kinda having work around it.

[thesteve]

thats how the pots look
look for other reasons first

[BlueBMW]

Also, are you running burns or originals.  These systems have a really hard time reading burned discs.

[IrishNinja]

thats how the pots look
look for other reasons first

yeah?  it just looks a bit off...okay, guess that's how its supposed to be?
or were you referring to another post?

Also, are you running burns or originals.  These systems have a really hard time reading burned discs.

trying original discs, just "PLEASE SET DISC" error previously mentioned in this thread, so far

[Chester77]

Ok, my problem has been solved.

In my experience DUO-R do not have a hard time reading CD-R. I was having trouble with CD-R and originals.

I say in my experience because between me and my brother we have 3 of these units.

I purchased a known working DUO-R from ebay (from japan) last week and it arrived today. Coincidentally so did my replacement laser unit (also from ebay).

I had borrowed my brother's DUO-R and over the weekend and tested all my discs on it. No errors or issues playing an disc.

I tested my new DUO-R from ebay and found the results to be the same. Perfect.

I did not want to open his unit because it is working properly and it has a region mod switch and I didn't want to disturb anything.

I opened the new DUO-R and measured the pots. The results are as follows:

VR101
AB:10
AC:9
BC:15

VR102
AB:8
AC:10
BC:12

VR103
AB:6
AC:14
BC:15

VR104
AB:7
AC:10
BC:15

VR105
AB:.5
AC:0
BC:.5

I replaced the laser on broken unit and tuned the pots as close as I could get them. The replacement of the laser unit was unbelievably easy. I couldn't believe it literally took 30 seconds.

The results for the pots were as follows:

VR101
AB:9
AC:10
BC:14

VR102
AB:8
AC:8
BC:12

VR103
AB:4.5
AC:14
BC:14

VR104
AB:15
AC:7
BC:10

VR105
AB:.5
AC:0
BC:.5

The result.... I now have 2 perfectly working DUO-R systems. The inside of the unit from ebay is extremely clean and the hu card slot seems to work perfectly as well.

I guess I will sell one now.

I paid $335 with shipping.

A reasonable offer would not be refused. If anyone is looking for a system.

Thanks for the suggestions, and I hope this info is helpful.

[thesteve]

fact is the duo and duo-r have the same drive and with the same laser will read equally well on CDR and originals
that said i have seen more marginal parts on the duo vs the duo-r (likely because its older)

[Chester77]

fact is the duo and duo-r have the same drive and with the same laser will read equally well on CDR and originals
that said i have seen more marginal parts on the duo vs the duo-r (likely because its older)

I can only speak of what I know. I only know about the DUO-R.

I didn't make any comment about the DUO or any other variant.

[Chester77]

what can i do here?  it showed up like this and i'm not certain if i have enough on the side to maybe catch with a pair of needle nose pliers and adjust that way, or should i try to remove it & replace with something else (assuming that's even an option)? or is it supposed to look like that?  appreciate any help i can get here. 

It looks very damaged.

Take the measurements (if you can) with an ohm meter. Compare them to the measurements I posted.

If they are similar you may want to try a new laser unit.

Adjustment is very fine and needle nose pliers might not do the job. You need to turn just a fraction at a time.

[bishopcruz]

Ok, my CD laser appears to be stuck, all the way on the outside of the track on my OG PCE Duo. The CD won't spin and I tried moving it back manually, and it seems quite stuck. Am I going to have to open her up in order to get everything working I assume?

Also, in some games, especially burns, the audio would randomly cut out, though this did also happen on some of my old retail games that had scratches. I assume I need pot adjustment.

Finally, someone mentioned I need to lubricate the gears on my Duo, I saw something in the OP about lubricating the rails, but nothing about the gears themselves (unless I missed something) What isthe procedure for that?

[thesteve]

The og duo can get stuck like that any time its having read issues
You will need to open it and spin the motor gear 2

[bishopcruz]

The og duo can get stuck like that any time its having read issues
You will need to open it and spin the motor gear 2

Yeah, opened her up, didn't realize just how much force was going to be needed to spin the gear, the rails seem lubed up and clean already, which is nice, now to mess with the pots. Which pot is it for audio cutting out on a bad read?

[thesteve]

Vr104 is focus, Vr103 is focus comp
Vr101 and Vr102 are tracking
Vr105 is spindle comp
Crackle is either focus or tracking
Spindle comp will cause early or late track issues 2

[bishopcruz]

Vr104 is focus, Vr103 is focus comp
Vr101 and Vr102 are tracking
Vr105 is spindle comp
Crackle is either focus or tracking
Spindle comp will cause early or late track issues 2

Any tips for getting the spindle pot working again? I had everything just about perfect then my hand slipped while dealing with vr 105, now I can't get it to read discs anymore, I've been using small increments, as I did with the other pots, but nothing, I'm hearing a clicking, which I assume is the gears, and a high pitched whining at times as well. I wasn't hearing the whine before I screwed up on 105.

[thesteve]

Slipped?
Did you hit something with a screwdriver?

If not center the pot and try again 2

[bishopcruz]

Slipped?
Did you hit something with a screwdriver?

If not center the pot and try again 2

TUrned a little bit farther than I expected. Not TOO far, but clearly enough.

[thesteve]

The pots spin all the way around without breaking
Just spin it back
 2

[bishopcruz]

The pots spin all the way around without breaking
Just spin it back
 2

That's what I did, it's just refusing to work now, was at it for hours last night.

Appreciate the help though.

[bishopcruz]

Welp, got it working again, it's still giving me hell on a few of the burns I have, but at least my physical games are working. I may open her up again once I am done with a couple of my regular games and see if I can get it working a bit better with burns. The fix, messing a little with VR 102, which I hadn't touched at all for the whole experiment. No idea why that worked, but it at least got me back to being able to read an audio CD, and was then able to follow BlueBMW's tips and even got my scuffed up YS III working, the music in the mines is no longer cutting out on that one at least.

[bishopcruz]

Ok, ready to do what will hopefully be the last adjustments I will need for the pots. Mainly to see if this thing will read CD-Rs well (The discs I burned worked great on Irish Ninja's DUO-R once we got it working. But either won't load, or audio cuts out on mine.) I found an older-ish multimeter to test the resistances, but it is manual. The question I have is that there are several settings for resistance on the thing. It starts at 200ohm, and then goes to 2000, 20k, 200k, and finally 2000k. What should I have it set to to measure the pots? Also, since I'm measuring resistance, it shouldn't matter which color goes on which point correct?

Yeah, this is fairly noobish, but I haven't done much electronics work since around my first year in college and I am rusty as all hell.

[IrishNinja]

The discs I burned worked great on Irish Ninja's DUO-R once we got it working.

well, that's not true at all, is it?  why, i went to boot up my 3-in-1 and Grand Master Meio killed me good. 

[Zer0-2k11]

Hey everybody,

First poster here, loving the contents of the forum so far. Hope i can contribute to the forums as much as i can.

I recently received my first PC Engine Duo the other day from eBay but it had audio issues and a full recap has seemed to fix the issue  , but now i got a bit of a problem now with the CD drive. I didn't have any original HuCards or Super CD games on hand so i decided to give a backup a try and the system wasn't reading it well and would boot the game 1/10 times. Afterwards i went to try to make adjustments in small increments with the pots on the motherboard but in the end, i stupidly turned all the pots a good bit and lost track. I normally would busted out my multimeter and used the charts to listed in the first few posts to get back to somewhat normal readings again but i dont know what the 2nd post means by "AB" "AC" "BC". Does anybody what this means?. I have done Gamecube pot adjustments and it was just a simple ohm reading. My multimeter is giving problems so i have to wait intill my next paycheck to get a new one (BK Precision) and also get a new HOP-M3 just in case, but i figured i would ask the necessary questions beforehand so i when i get the multimeter and the new laser, i can know before hand and it bring it back to life and get it running like new again. Can i still revive this PC Engine DUO or is it screwed? .

Thank you everybody for their time and patience.

[thesteve]

you cant kill anything by turning the main board pots
the pot on the laser can damage the laser

[Zer0-2k11]

Thank you thesteve,

I managed to get the CD drive working again using a retail disc of Eden of the East. I got CD drive working again by replacing the laser and using the values noted in the link on the 2nd post. I used the last few posts in that thread. I used the DUO-RX readings then used the VR104 value on another post. May need more turning to play CD-R's working but i got audio issues again . Got to fix that first.

[Ripthorn]

Hey guys, first post here.

I want play the Castlevania fan translation, so I ripped my original disc and then I applied the patch.

Burned in 10x (minimum possible speed) and tested on my original Duo.
No problems with gameplay, just the audio tracks that play a bit and then stops. Sometimes the Richter  sprite appears garbaged.
The original disc plays without problems, the translated version plays without problems on emulator.

So that means I need to replace cd lens?
Calibrate pots?
Use other cd brand (tried two)?
Change caps?

I would appreciate if someone could help me.

PS: Sorry for my bad english.

[Tempest_2084]

Hi,

I've just completed the laser replacement and everything went very smoothly (or so I thought).  However no matter what I do the CD will not spin and eventually I get a Set Disc error.  I did a basic continuity test on the wires and they all seem good at least I think.  On a hunch I put my old laser back in and it also will not start spinning the disc. 

Since both the old and new laser don't seem to be detecting the disc I guess I must have broken something when I removed the laser.  I can't see what I could have damaged as it was very simple and I followed the guide.  Any ideas?

[Keith Courage]

Please take some pictures. I can't think of anything that could have gotten messed up other than some wires getting pulled.

Just to make sure I have this right. Your old lens worked before trying to install a new one but now neither will work?

[Tempest_2084]

Yes that's correct.  The old lens not working is what's really stumping me.

Pictures.  Note that the board to the left is a RGB mod and has nothing to do with the laser (everything including the RGB mod was working before I tried to install the new laser).

[Keith Courage]

Did you ever at one point try to adjust the pot on the lens itself? If so you should check the contacts for said pot since sometimes turning them can sometimes crack the solder joints.

[crans]

The points at the start of this thread are great at getting you moving. It would best to start with the best music CD you have to test the new laser.

The cap work on this looks factory quality so that cant be it. Where did you get this "new" laser? I have had my share of "new" old broken, reworked,china CRAP!

[Tempest_2084]

I did go through the guide here first, but nothing helped.  I really REALLY don't want to adjust the pots as I hear you can screw crap up that way and they worked with the old laser anyway.  I did play with the pot that supposed to control the CD spindle, but I put it back to where it was after that didn't do anything and the CD wasn't spinning before anyway so I don't think that could have done anything.  I never touched the pots before that.

I got the laser off ebay from the seller a lot of people get theirs from (he's from the USA, that's all I remember).  However if it was a bad laser or pot setting I can't see why the old one wouldn't work, that's the mystery.  To me that points to bad or broken wiring, but I did a continuity test on the wires and they all seem ok as far as I can tell.

I tried a music CD but it still won't spin.  What wires control the CD spinning?

[thesteve]

wont spin is an early fail
no cd in
door switch pressed
hit run
the laser sled must bump the center switch, then bob
laser must light
check and report

[Tempest_2084]

Yes it does all that.  I assume by 'center switch' you mean the cd spindle?

[thesteve]

there is a switch by the spindle the laser sled must hit before looking for the disc

[Tempest_2084]

Ok I think I see it.  The sled does bump that switch, but it doesn't look like it pushes it in very far.  I moved the sled over so it totally pushed the switch in, but still no spin.    How much does it normally push that switch in?

EDIT: Looks like that switch just makes the laser go back to the left. I held it in and the laser went all the way the other direction.  So that would make sense if it only bumped the switch lightly and bounced back a bit.

I did a continuity check on the two wires going to that switch.  They seem alright.

[thesteve]

next 1 will be harder to see
disc in run
centers, laser bobs 1 time and locks on