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

[MotherGunner]

Holy crap, where was I on this thread?

[kisaku]

Hello, before touching something i would like to ask here.
My DUO black is doing "please set disk" when i put a game disk. Audio disks work but sometime audio goes bad. Is it a Caps problem or a calibration lens problem?
Thanks

[BlueBMW]

If the caps havent been done yet then I would start there.  I've seen bad caps affect CD playback for sure.

[kisaku]

If the caps havent been done yet then I would start there.  I've seen bad caps affect CD playback for sure.

I understand. Don't you think pot calibration can resolve the problem? is risky to do before caps?

[BlueBMW]

I would leave the pots alone until you do the caps.  It may be possible to adjust the pots to compensate but some of the caps affect the operation of the laser.  I have had several duos that didnt read discs before a cap job start working perfectly aftewards with no adjustment.

[Vimtoman]

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.

Thanks Chester77 this worked for me and my Duo-r is reading every stubborn disk i have.

I would setup using counters and scopes but thought I'd try this first and it reading so quick now.

[deubeul]

Okay, thesteve has pretty much un-idioted me, by which I mean to say that he has taught me very quickly how to use my oscilloscope, which is the greatest tool in the history of ever, and which I consider to be invaluable for anyone attempting to tweak their PCE CD system (whatever it may be) back to life.

Seriously, I can't overestimate how immensely powerful even a cheap scope like mine is.

As far as the white lens pot is concerned, most of them should come with a hard epoxy on the pot, locking it in the factory-determined ideal impedance.  That being said, it's okay to have it 'too strong'.  Sure, it'll shorten the lifespan of the laser itself, but better overpowered than underpowered.

VR105, as I've said before, should be clocked at a fairly precise 4.3MHz frequency.  Because the very nature of a waveform is its undulation, you're going to get readings at both the top and the bottom of the waveform, meaning you'll see the frequency go up and down on your meter.  As a rule of thumb, try to get the frequency of VR105 to go NO LOWER than 4.321MHz, which should mean your peak should be at 4.400MHz, or more likely just under.  Again, better a little strong than a little underpowered.  A decent frequency counter (at least 10MHz) shouldn't cost you more than $15 USD on eBay, and is well worth the investment.

VR103 is your go-to pot if you have scratchy sound or sound that drops out.  On all the Duos I've played with, it seems to have a very, very small window of perfect operation - maybe ten degrees or so, but I'm not sure if this is typical, as my sample group is comprised of the four Duos (all PCE) I have ever seen.

If you're starting from scratch on adjusting the pots, thesteve's directions are perfect:

1)  Pull the RF signal from pin 2 on the P5 connector, and ground it on pin 1 of P5.
2)  Set your scope to 2.00V/Div and 1.000us/Div.  Get your readings while your CD system is trying to load the disc.
3)  While the CD attempts to load, use a plastic or other non-metal small Phillips-head screwdriver to turn VR102.  You're trying to get the greatest amplitude (biggest wave) you can.  Once you've found the spot that makes the wave as large as it can be, move on to VR101 and do the exact same thing.
4)  After you've made the biggest wave you can, set your scope trigger to be at the far left of your screen, and about 3/4 of the way up the waveform you're pulling.  Turn VR104 clockwise until the disc stops spinning.  Once this happens, make the smallest turns you can COUNTER-clockwise and wait a few seconds between each turn to see if the disc starts spinning.  Once it does, move on to VR103.
5)  VR103 is kind of the odd pot out - it's incredibly touchy, and it seems to vary on a per-Duo basis how to set it.  Ideally, you want to turn it until your drive is making no real noise - no squeaks, no whines, no chugs or repetitive clicking noises.  It should run almost silently.  You can find your starting point by turning it counter-clockwise until it starts making a faint whine-like noise.  When this happens, turn it CLOCKWISE by a hair, and I do mean 'just a hair'.  I'm not exaggerating when I say that the VR103 pot has a very small window of operation.  Use a game with a soundtest available right off the bat, like Rondo of Blood.  Playtest the first and last tracks while making minute adjustments.  There should be no crackling or audio dropouts at all.  This can take some time, so be patient, and you'll pull through.

Few questions about scopes / frequency counters:

- would scopes like this would do the job?:

http://www.ebay.fr/itm/Kit-Oscilloscope-DSO138-2-4-TFT-numerique-DIY-Parts-Set-electronique-1Msps-/131538450791?hash=item1ea04d7967:g:CREAAOSw37tWA5z-

- If yes, Do I still need a FC like this for VR105?:

http://www.ebay.fr/itm/KKmoon-Frequence-de-loscillateur-cristal-MHz-50-Counter-testeur-Kit-0WN8-/181825855970?hash=item2a55aa61e2:g:-xYAAOSwpdpVXeAq

-If not, what type/model of scope would be required to set/verify  lasers on Duos/CDromroms ?

[thesteve]

fact is the DSO may or may not, as nobody has tried one yet
you will never need the FC for VR105

[deubeul]

Thanks for answering Thesteve. 

This made me think afrequency counter would be usefull for VR105:

VR105, as I've said before, should be clocked at a fairly precise 4.3MHz frequency.  Because the very nature of a waveform is its undulation, you're going to get readings at both the top and the bottom of the waveform, meaning you'll see the frequency go up and down on your meter.  As a rule of thumb, try to get the frequency of VR105 to go NO LOWER than 4.321MHz, which should mean your peak should be at 4.400MHz, or more likely just under.  Again, better a little strong than a little underpowered.  A decent frequency counter (at least 10MHz) shouldn't cost you more than $15 USD on eBay, and is well worth the investment.

The fact is I already have a DIY scope like the one I linked, but the screen arrived broken. I've been refund, but now I hesitate to buy a new one, especially if it's useless for PcE lasers.

[thesteve]

think of VR105 like the V-Sync knob on the old TV
it sets an oscillator slope, that needs to be reset by the CD data before it reaches its freq setting
if its too low it could pickup harmonics, but set too fast it will cut the data frames short and fail to read the disc

[Phase]

Got a few questions here
I just recently got around to capping my duo,(I decapped it after I got it a few years back but never got around to the recap ) its running good now and I also just fixed the high pitched ringing noise by adjusting pot 102 a quarter turn cc like mentioned here
http://www.pcenginefx.com/forums/index.php?topic=3586.msg122549#msg122549

Just wondering when should you replace the laser? what are the problems the lasers start to have?

Also about putting the board in the dishwasher, Is it ok to do this with the new caps and all?
And what about dishwasher settings and the hot steam dry is this all ok?
for oven drying what temp do you want and how long.. can I bake at the same time?

I had trouble with a few pads that must have had old capfluid or something in the old solder, ended up hitting them a few times (possible burning the stuff away) before I got some solder on the board but they look a little dirty, is this going to be ok? or should I redo them and try and get rid of the old solder?  (I’m a bit of a novice and have only done minor soldering here and there)

[thesteve]

washer is fine, normal settings (anything loose may come loose so be aware of it)
as far as laser failure it happens several ways
some wont read certain discs, where others just stop reading
some work for awhile and stop, then work again later

[SegaSonic91]

It's been a long time since I took the screws out of my PCE DUO, and I seem to have "misplaced" them.  I always planed on replacing those torx #10 screws, one of which stripped and was a complete bitch to get out, with regular Phillips once the thing was complete.  I tried looking for "#40 1/2" pan" but never found anything that looked right.  So for instance, is http://www.ebay.com.au/itm/Qty-5-Pan-Head-Machine-4-40-UNC-x-1-2-Stainless-SS-304-Screw-Phillip-Bolt-BSW-/231669035899?hash=item35f08cf37b:g:jPoAAOSwMmBV4HC7 correct?  They look far too long to me.

[mickcris]

It's been a long time since I took the screws out of my PCE DUO, and I seem to have "misplaced" them.  I always planed on replacing those torx #10 screws, one of which stripped and was a complete bitch to get out, with regular Phillips once the thing was complete.  I tried looking for "#40 1/2" pan" but never found anything that looked right.  So for instance, is http://www.ebay.com.au/itm/Qty-5-Pan-Head-Machine-4-40-UNC-x-1-2-Stainless-SS-304-Screw-Phillip-Bolt-BSW-/231669035899?hash=item35f08cf37b:g:jPoAAOSwMmBV4HC7 correct?  They look far too long to me.

They probably have a generic picture there.  The screws you need are some type of course thread. I have not ever measured them though but that is definitely the wrong kind of screw and wrong thread.

edit:
i did a rough measurement.  They do look close to a #4 so im guessing its actually an M3 and they are about 12mm long.  This is my best guess as to the size.  not 100% sure this is correct though
http://www.ebay.com/itm/20X-M2-M5-304-Stainless-Round-Head-Phillip-Pan-Head-Flat-Tail-Self-tapping-Screw-/171951921628
black
http://www.ebay.com/itm/100PCS-M3-M4-M5-Philips-Round-Head-Screw-Self-Tapping-Horizontal-Tail-Bolt-Black-/272013654380

can maybe find those locally or a cheaper listing on ebay with less quantity

edit again:
updated the link with ones that have the same flat bottom

[blueraven]

can maybe find those locally or a cheaper listing on ebay with less quantity

Phillips Pan Metal Screws: #4 x 1/2in available in 100 packs at ACE Hardware for just over $12

If you send me an address, Segasonic91 I can send you 5. I always have a box of these lying around.

Good link Mickcris, the only thing that would be in question is the length. 1/2" is appropriate, and 5/8" will work is the bolt is stripped, but I wouldn't go any longer or shorter here. The Duo wont close properly.