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

[mickcris]

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.

I measured again and the OG screw threads are exactly 12 mm long.  They have them in 14mm also if you want some longer ones.  I am assuming, since these systems were made in Japan, the screws are metric.  12mm is 0.472441 inches and 14mm is 0.551181 inches.  Im not sure from his post if the head is stripped or the inside of the hole.  The ones you are using may have that split in the end which makes less threads where the ones i have linked have threads the whole way to the bottom like the originals.  like this one that will not hold as good cause of its end:
http://www.homedepot.com/p/Everbilt-8-x-3-4-in-Zinc-Plated-Self-Drilling-Pan-Head-Phillips-Drive-Sheet-Metal-Screw-100-Piece-per-Pack-801042/204275119

I was only not sure about the M3 size but I think its coorect

[blueraven]

Here is what I'm using:

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.

I measured again and the OG screw threads are exactly 12 mm long.  They have them in 14mm also if you want some longer ones.  I am assuming, since these systems were made in Japan, the screws are metric.  12mm is 0.472441 inches and 14mm is 0.551181 inches.  Im not sure from his post if the head is stripped or the inside of the hole.  The ones you are using may have that split in the end which makes less threads where the ones i have linked have threads the whole way to the bottom like the originals. 

I was only not sure about the M3 size but I think its coorect

I assume that you are correct about the metric sizes versus standard, I will say that this was a suitable alternative for the time being, but I was wondering about the pitch of the threads. I have had some cases where repetition of removal/install has broken down the posts and left the system running with 4/5. They do have threads going all the way down though. I could look for the metric equivalent.

[mickcris]

they are self tapping so the the original screw cut the threads. Not sure if the metric and standard thread pitch is the same so using those ones could possibly be damaging the holes if they are not the same.    You need to make sure the screw is going into the originally cut threads or it will strip out the hole.  I use the method that game-tech-us was recommending in one of his videos where you turn the screw ccw till you feel it go back into the hole and then start going cw.

edit:
those ones you have do have that point at the end which is counted in the length.  that part of the screw is not going to be doing anything.  so that is going to make the threads maybe about a mm shorter.

[NightWolve]

Yikes, I never shop at ACE Hardware unless I just need something in the dollar range...

Got ripped off so bad there on so many things compared to what I saw when Menards and Home Depot came around... They're the absolute worst with the highest prices on everything.

[blueraven]

Yikes, I never shop at ACE Hardware unless I just need something in the dollar range...

Got ripped off so bad there on so many things compared to what I saw when Menards and Home Depot came around... They're the absolute worst with the highest prices on everything.

Yeah they are. The place I went to years ago had a 25% off sale which made them about the same price as Harbor Freight.

...could possibly be damaging the holes if they are not the same.    You need to make sure the screw is going into the originally cut threads or it will strip out the hole.  I use the method that game-tech-us was recommending in one of his videos where you turn the screw ccw till you feel it go back into the hole and then start going cw.

The threads lined up perfectly (or so I thought) when I checked the screws against the Safety bits that came out of the Duo. Most of the systems haven't broken a post due to this issue, rather the brittle nature of the plastic and having been opened up too many times. Also, yes, I do turn them CCW before insall to make sure that they are seated.

...so that is going to make the threads maybe about a mm shorter.

On the bottom end, yes. I hadn't thought of that.

[mickcris]

Yikes, I never shop at ACE Hardware unless I just need something in the dollar range...

Got ripped off so bad there on so many things compared to what I saw when Menards and Home Depot came around... They're the absolute worst with the highest prices on everything.

Yeah they are. The place I went to years ago had a 25% off sale which made them about the same price as Harbor Freight.

...could possibly be damaging the holes if they are not the same.    You need to make sure the screw is going into the originally cut threads or it will strip out the hole.  I use the method that game-tech-us was recommending in one of his videos where you turn the screw ccw till you feel it go back into the hole and then start going cw.

The threads lined up perfectly (or so I thought) when I checked the screws against the Safety bits that came out of the Duo. Most of the systems haven't broken a post due to this issue, rather the brittle nature of the plastic and having been opened up too many times. Also, yes, I do turn them CCW before insall to make sure that they are seated.

...so that is going to make the threads maybe about a mm shorter.

On the bottom end, yes. I hadn't thought of that.

Yeah, I think sometimes there is nothing you can do to stop them from stripping out the threads in the hole.  I looked it up and it seems like M3 may be a hair larger diameter than #4 so that could maybe also be a factor. Not sure if it's enough to make a difference. I'm pretty sure now that those ones I linked to are the same size as the originals.

[Vimtoman]

Never mind. Wrong ones you were talking about.

[Punch]

snip

[MNKyDeth]

I've been doing some adjustments (with the aid of a multimeter to be able to record "default" values) and nothing was really working for CDRs until I got enough courage (or was stupid enough) to mess with the LASER pot. I did less than 10 degrees clockwise and finally a lot of games on CDR started to work flawlessly! Lords of the Rising Sun and Raiden are two of which I'm now enjoying.

Quite oddly, my silver 650MB Mitsuis are not working, but a cheap ass CDR (by Ritek) works very well lol, so much for superior CD quality. The cheapo discs are less "transparent" than the 650mb discs so it might be the reason for working well. I've solved ALL problems, except for...

Yeah, it has problems when seeking late tracks. As you can see in the video (please excuse my sloppy disc handling ), Riot Zone "boots" but it immediately tries to read a late track on the disc. The laser goes to the edge, the CD spins at max speed, and nothing works. This also happened with my Mitsuis when they used to work (I don't have any spare ones anymore so I cannot do further testing). I never observed any issues with pressed discs (official ones or repros from the King of Scanline Generators).

What pots should I focus on (if at all)? I'm quite frankly tired of doing trial and error with them.

If you only have a multimeter check out page 5 if this very thread. Chester77 listed default vaules. They work very well in most systems I have tried them on.

[Punch]

I've been doing some adjustments (with the aid of a multimeter to be able to record "default" values) and nothing was really working for CDRs until I got enough courage (or was stupid enough) to mess with the LASER pot. I did less than 10 degrees clockwise and finally a lot of games on CDR started to work flawlessly! Lords of the Rising Sun and Raiden are two of which I'm now enjoying.

Quite oddly, my silver 650MB Mitsuis are not working, but a cheap ass CDR (by Ritek) works very well lol, so much for superior CD quality. The cheapo discs are less "transparent" than the 650mb discs so it might be the reason for working well. I've solved ALL problems, except for...

Yeah, it has problems when seeking late tracks. As you can see in the video (please excuse my sloppy disc handling ), Riot Zone "boots" but it immediately tries to read a late track on the disc. The laser goes to the edge, the CD spins at max speed, and nothing works. This also happened with my Mitsuis when they used to work (I don't have any spare ones anymore so I cannot do further testing). I never observed any issues with pressed discs (official ones or repros from the King of Scanline Generators).

What pots should I focus on (if at all)? I'm quite frankly tired of doing trial and error with them.

If you only have a multimeter check out page 5 if this very thread. Chester77 listed default vaules. They work very well in most systems I have tried them on.

they don't work on mine.
Did final adjustment to 104 since my original Buster Bros. didn't work, now all discs work like a charm (with the exception of problematic end-of-disc data track CDRs).

[Punch]

Punch vs. CDR, the fight continues.

So nothing was playing reliably despite what I posted (I found out later...), my buddy chop5 told me to set laser pot to 0.8 (I don't remember what's the ohm rating for it so I don't know the scale), and now it seems that I can play all my retail games OK, but discs are still finicky.

I'll explain: I made a CDR with Beethoven's 9th Symphony, 4 tracks plus this one here: https://soundcloud.com/twinbros/ti-amo-japanese-coverversion (yes it's supposed to stand out from the classic music plus I like it, so what). 5 tracks total, 71'29''
1 - 16'24'' - 1956 Beethoven 9th concert 1
2 - 14'48'' - 1956 Beethoven 9th concert 2
3 - 13'55'' - 1956 Beethoven 9th concert 3
4 - 22'56'' - 1956 Beethoven 9th concert 4
5 - 03'24'' - Ti Amo (Be-2)

When playing the CDR, it gets to the audio player quick, no issues, and it plays both 1st and second tracks fine. Fast forward was 'slipping' and landing like 30 seconds forward instead of the steps of one sometimes but I fixed that. Now for the problems...
Track 3 doesn't start when requested half the time, and when it does the audio is noisy (aka low quality signal, so much for being digital huh Compact Disc), Tracks 4 and 5 don't start at all and the poor laser keeps trying to reach it to no avail.
edit: I left the duo playing while I wrote this post and indeed, Track 2 also gets noisy when approaching the end (aka the beggining of disc 3).

Conclusion, and also a bookmark for your tl;dr people: I guess now the only thing I can do is procure better cds. As I said before I'm using generic 80 minute discs, and I don't have my 650 silver mitsuis anymore so I can't test it again (it's a long story). If someone had any luck with CDRs on your US Duo please post here, because I can only find people that got pissed off and just moved on to an RX or SCDROM2 or people that are "meh I don't play CDRs on mine". I thought that the Duo laser was/is a very popular laser? How come it doesn't like CDRs?

I'll source for more types of cds and I'll post my findings here later, but I think I did what I could adjustment wise.

[TheOldMan]

5 tracks total, 71'29''
...
4 - 22'56'' - 1956 Beethoven 9th concert 4
5 - 03'24'' - Ti Amo (Be-2)
...
 Tracks 4 and 5 don't start at all

Probably not. The cd player was only designed for 60 min cds.
Track 5 is definitely out of range, and track 4 would have an end point out of range (making it an invalid track)

[Punch]

Very interesting, thanks TheOldMan. Guess I need to find a better way of testing discs. Do you know if there's any limitations in the CD BIOS search and play routines or is it something from the audio player program itself? Can't find anything on Hu7 documentation about max length.


edit: if you mean the disc drive itself was meant only for 60 mins max, that explains a lot. But I thought 74 min was the max. playback/storage time :/

[NightWolve]

5 tracks total, 71'29''
...
4 - 22'56'' - 1956 Beethoven 9th concert 4
5 - 03'24'' - Ti Amo (Be-2)
...
 Tracks 4 and 5 don't start at all

Probably not. The cd player was only designed for 60 min cds.
Track 5 is definitely out of range, and track 4 would have an end point out of range (making it an invalid track)

Good eyes old man! I wouldn't have caught that.

[TheOldMan]

Do you know if there's any limitations in the CD BIOS search and play routines or is it something from the audio player program itself?

I haven't yet seen any limits in the bios on track lengths or position. But that's not where I would expect it anyway.
The cd system works by sending command packets to the scsi controller. Play is actually sent as 'seek to position ' and 'play to position' (from current). One of the things the routines have to deal with is a 'bad parameter' value - which is detected by the controller.

Basically, what that means is the scsi controller itself probably checks the locations, and returns an error if its out of range.

if you mean the disc drive itself was meant only for 60 mins max, that explains a lot. But I thought 74 min was the max. playback/storage time :/

Yes, the drive/controller can only reliably use 60 min / 650 M cds. Technology marches on.
I suspect that the controller limits were set higher then 60 min to allow for 'new' technologies on the near horizon, or for larger, in-print cds.

I remember something about the developers wanting all of a bach piece on 1 cd, so thats how they set the initial size. I also remember when 70 min cds came out, and being disappointed they wouldn't work in my 2x burner

I suspect that's also part of why some discs cause the laser to stick. The seek doesn't return an error (because the limits are larger than they needed to be, for the future), but the drive mech can't handle it.