Sega CDX laser calibration without opening the console

[segasonicfan]

ifkz, could you post some more info on this? I would love to know:
1) where you bought your laser (some ebay sellers are selling bad ones)
2) what was the resistance of the pot after adjusting
3) what specific behaviors should I look out for on my laser?

I spent a couple hours toying with my dying laser and a "new" SCF93 which turned out to be an 8 pin model I bought last year (doh). Took a while before I figured out I was wasting my time with it. One thing I did learn was that the POT is actually rhetostat, i.e. its only connected with 2 pins. So the best way Ive found for adjusting these (and it is amazingly less hair splitting) is to remove the POT, solder two wires to the points it was at, and solder a precision POT externally in its place. Then you can adjust it while its looking for the disc to see its behavior. Also hookup an ohm meter easily for real-time readings.

I have 2 old lasers (one from another broken CDX I have) and the 8 pin one. The dying (but working one) measured 675 ohms before making any adjustments. However, after adjusting a little and putting it back to that, it no longer works Im not sure what I did wrong or if these lasers are just terribly fragile. It just spins, stops, spins, stops, etc.

Anyway, if you could offer more detail on your successful fix it would be great I hope to make a video when my new laser comes in the mail to help people fix this great system.

-Segasonicfan

[ifkz]

I sent you a PM on this.

Basically, I did post technical help for the CDX but found members were fixing their systems and then asking for places to download ISOs of the library to rip off games. I'm a hardcore purist, with 2/3rds of the original Sega CD library, I got majorly pissed and took the info down. Unintended consequences of trying to help the community.

Anyhow, back to your CDX, you should not have to adjust the pot from a new NOS 10 pin laser. You've seen the ebay seller that everyone uses (Danyalbi ...may be spelling that incorrectly), so I would buy one for $18 and you should be good. Once the pot on this laser is adjusted, it's a real big problem to get it right again. Took me months with several different condition CDs!

If the laser doesn't fix it, it is going to be something else. For one of my repaired units, it was careful, minute measured adjustments of a couple of the pots on the main topmost CD motherboard that got it working again.

One of my others had multiple problems: someone had gotten into it and royally screwed it up. The ribbon cable was disconnected from the topmost CD motherboard, they had lost the small spring that pushes the CD track into the toothed gear, the "new" laser had a broken off pot connection, the copper shielding had a rips along the solder tabs, a cap on the powerboard was bad. Now it's my main unit until I get nutty enough to buy another broken one.

Anyhoo, probably said too much here; I hope this helps the purists that actually collect and cherish the Sega CD hardware and retail pressed games.

One more tip. Be sure to clean the laser rod that it travels on and put some new white lithium grease on it. Some of my games would randomly crash on one of my repaired units, but has been perfect with the new grease. You can get it at any hardware store or ebay.

[sonicfan]

Hello ifkz, I'm kind off in the same wagon. Do you happen to remember which cap you replaced for the fix? Any tips adjusting the board pots? thanks.

I only play original Sega cd games too. but apparently the previous owner abused the system with CDr's

[ifkz]

Hello ifkz, I'm kind off in the same wagon. Do you happen to remember which cap you replaced for the fix? Any tips adjusting the board pots? thanks.

I only play original Sega cd games too. but apparently the previous owner abused the system with CDr's

Well, I can tell the cap was on the small power board, and was buldging and leaking, so I took it out. It was only something that would happen if a wrong power supply is used. My guess is someone had used an under-amped Genesis 2 adapter with it, but that's just a guess. If your powerboard caps look fine, they likely are fine.

Under most normal circumstances the main top board pots should NOT be adjusted. That particular unit was still having seek and track playing problems after a NOS laser and the board pots were a last gasp chance at getting it working again. Thankfully it worked.

[segasonicfan]

Thanks for getting back to me and *wow* sounds like you really know your stuff! I'm currently doing some extensive CDX documenting right now, including researching the chipset, fixing all the video noise problems, and installing Tiidos crystal clear audio mod. As far as I know, no one else has traced out the audio signals to do it, so you might dig this if you love CDX like me:
http://nfggames.com/forum2/index.php...33023#msg33023

I'm much more active on that forum and sega-16 so I did not get your message until just now.

I sent you a PM on this.

...Once the pot on this laser is adjusted, it's a real big problem to get it right again. Took me months with several different condition CDs!...

This is what I would love to know more about. While I did order a new laser I still have 2 others. One was partially working (would skip sometimes) but after adjusting the pot on it, it no longer reads anything >_< The original measurement was 675ohms (its a rhetostat actually, not wired in as a real pot) and setting it at that value did nothing. Bringing it down to ~350ohms it will spin the disc and search but I never get a "01" track listing on the display. So it really isnt seeing much. I've fiddled with it for hours and nothing seems to work. How did using different CDs help you? What behaviors other than spinning did you look for? Would adjusting the pots on the CD board help at all ?

Thanks for the headsup on the greasing. I figured that would be wise when I was looking in there. And that darn spring! One of em flew off into the abyss of my room. Found a good replacement though.

I think you'll be interested in some of the mods I'm doing, I'll post back here when I get things finished up. Going to install a CXA2075 among other things too

-Segasonicfan

P. S. Legit CDs are always the way to go. I'm pretty sure burns damage the laser and all the dumps online have audio in MP3 format-- to hell with that!

[ifkz]

My knowledge comes from more trial and error than anything, it sounds like you are well on your way to discovering repair techniques I don't know about!

You'll have to get that pot on the laser back in adjustment before you do anything else to it, I hope you haven't messed with the other top motherboard pots (T.Gain, T.OFF, etc). Basically, when I threw my laser pot out of adjustment, I had to re-assemble the bare circuit board sandwich back together (leaving that large sheet of main copper shielding off) and soldering all normally soldered connections back together. Basically running the unit completely de-cased on a non-conductive surface (my wood desk). After that, it was easy to get to the laser pot adjusted to where it would start to spin the disc and read audio tracks.

On another unit, I had to do the same de-cased madness only to find that a solder tab had broken off of the pot, rendering it useless. It would work with presure from my screw tip, but as soon as that went away, the connection was lost.

The other Sega CDs I used had varying levels of scratches that would react to anything but a perfectly dialed in laser pot. My copy of Shining Force CD will skip midway through the introduction audio unless the laser is perfect.

I have a stable of broken ones I've bought from ebay and fixed, and they have all needed new lasers. So far they've been at or near three figures when I'm done with repair and making complete, so I had to stop spending so much money on them.

I've become an active member on Sega-16, it is more in line with my collecting interests. Feel free to hit me up there, I just finished a post defending the Sega Cd with a best of list attached too. That and unearthing Genesis 3 compatibility restoration thread.

And good for you to collect the retail games. It's a hard road (there are a lot of damaged discs out there) but well worth it in the end IMHO. Heck, I have a few games with pinpricks of light that are placeholders; better than a CD-R anyday. And for some with these pinpricks, the Sega CD handles it and skips over the spot with no trouble (if it's in the audio track, for example). My copies of Panic! and Keio FS are like this and I still treasure them and their reproduction boxes. And games like Keio would cost hundreds to replace nowadays.

[segasonicfan]

Thanks for the reply, I left you a message over at sega-16. Tried the Dalbani laser but it was a no-go. You ever bought one that didnt work from them? Or where do you buy your lasers from?

[segasonicfan]

Fixed my system!

Thanks to the pictures & guide here:

http://www.briconsola.com/esp/cdxxesp.htm

and the service manuals for Mega CD 2 here:
http://www.sega-16.com/forum/showthr...-manuals-16bit

I learned how to adjust the pots on the daughter board to allign the laser right. Interestingly, you shouldn't need to adjust the pot on the laser itself-- Sega made pots on the boards that (in theory) do the same thing. I haven't found the "eye pattern" point on a CDX yet but I will soon...Basically you can use an oscilliscope to get the pattern right while adjusting the "E/F, B" pot. and once you get it to boot you can fiddle with the tracking gain "T. Gain" pot.

I also took measurements of the correct pot positions if anyone is interested. Works great with the 2 Dalbani lasers I bought! Plays Silpheed flawless...which is the most demanding on the system of any game I think

-Segasonicfan

[onetunafish]

Hey segasonic!

First congratulations on fixing the cdx, is no simple task! I have one I'm tring to fix but no luck thus far. No luck at all, even the new lasers I bought from liberty electronics were DOA. That was a few of months ago and and as I just saw your posts on the subject, perhaps there is some hope for me too.

Would you have the measurements for the motherboard pots? That would be amazing info for me, the one I bought came in all messed up and I have no idea how to try and adjust those. I also track down a couple of new lasers and try again, I'd love to see this unit working like it should.

ED!

Fixed my system!

Thanks to the pictures & guide here:

http://www.briconsola.com/esp/cdxxesp.htm

and the service manuals for Mega CD 2 here:
http://www.sega-16.com/forum/showthr...-manuals-16bit

I learned how to adjust the pots on the daughter board to allign the laser right. Interestingly, you shouldn't need to adjust the pot on the laser itself-- Sega made pots on the boards that (in theory) do the same thing. I haven't found the "eye pattern" point on a CDX yet but I will soon...Basically you can use an oscilliscope to get the pattern right while adjusting the "E/F, B" pot. and once you get it to boot you can fiddle with the tracking gain "T. Gain" pot.

I also took measurements of the correct pot positions if anyone is interested. Works great with the 2 Dalbani lasers I bought! Plays Silpheed flawless...which is the most demanding on the system of any game I think

-Segasonicfan

[dylbob42]

Fixed my system!

Thanks to the pictures & guide here:

http://www.briconsola.com/esp/cdxxesp.htm

and the service manuals for Mega CD 2 here:
http://www.sega-16.com/forum/showthr...-manuals-16bit

I learned how to adjust the pots on the daughter board to allign the laser right. Interestingly, you shouldn't need to adjust the pot on the laser itself-- Sega made pots on the boards that (in theory) do the same thing. I haven't found the "eye pattern" point on a CDX yet but I will soon...Basically you can use an oscilloscope to get the pattern right while adjusting the "E/F, B" pot. and once you get it to boot you can fiddle with the tracking gain "T. Gain" pot.

I also took measurements of the correct pot positions if anyone is interested. Works great with the 2 Dalbani lasers I bought! Plays Silpheed flawless...which is the most demanding on the system of any game I think

-Segasonicfan

hi, thank the google i found you!

i just spent my weekend trying to calibrate a cdx to a new laser and it been hell. I tried using a multimeter reference but that didn't work, been doing it by hand ,trial and error. adjust the pot, put cd on, turn on, turn off, take the cd off, adjust pot, put cd on, turn on....over and over. Got it from not reading to playing but not being able to load the next level (golden axe on the classics cd) to being able to load the next level. last issues are that the soundtrack wont play consistently and when i upscale the component signal there seems to be interference between the blue and green.

so in frustration i have decided that its time i got a oscilloscope, can i please get the measurements of the correct pot positions off you? Also do you have and advice on what to look for in a hobbyists oscilloscope?

cheers!

[dylbob42]

hi, thank the google i found you!

i just spent my weekend trying to calibrate a cdx to a new laser and it been hell. I tried using a multimeter reference but that didn't work, been doing it by hand ,trial and error. adjust the pot, put cd on, turn on, turn off, take the cd off, adjust pot, put cd on, turn on....over and over. Got it from not reading to playing but not being able to load the next level (golden axe on the classics cd) to being able to load the next level. last issues are that the soundtrack wont play consistently and when i upscale the component signal there seems to be interference between the blue and green.

so in frustration i have decided that its time i got a oscilloscope, can i please get the measurements of the correct pot positions off you? Also do you have and advice on what to look for in a hobbyists oscilloscope?

cheers!

btw ive got my heart set on a Rigol DS1054Z

[paulera]

Fixed my system!

Thanks to the pictures & guide here:

http://www.briconsola.com/esp/cdxxesp.htm

and the service manuals for Mega CD 2 here:
http://www.sega-16.com/forum/showthr...-manuals-16bit

I learned how to adjust the pots on the daughter board to allign the laser right. Interestingly, you shouldn't need to adjust the pot on the laser itself-- Sega made pots on the boards that (in theory) do the same thing. I haven't found the "eye pattern" point on a CDX yet but I will soon...Basically you can use an oscilliscope to get the pattern right while adjusting the "E/F, B" pot. and once you get it to boot you can fiddle with the tracking gain "T. Gain" pot.

I also took measurements of the correct pot positions if anyone is interested. Works great with the 2 Dalbani lasers I bought! Plays Silpheed flawless...which is the most demanding on the system of any game I think

-Segasonicfan

Hi folks.

First of all thanks for the info. It is so cool to mess with these old systems with all the info online thanks to people like yourselves.

Could you please share the measurements of the correct pot positions ? I am absolutely interested.
I just bought a Sega CDX and I tried burning some games at different speeds, with different writers and different CDs, but no matter what I try I couldn't succeed yet. I went so far as buying old Pioneer recordable CDs which some sites state to be the best there was, with no luck.
I have an Ecco the Dolphin official cd which loads just fine, it just skips some songs, so my guess is the laser is fine.

On my tests, most cds won't even turn, some of them do, the sega logo and music even stops, which seems it is about to load, but then it doesn't.

I'm getting this feeling I may get lucky just by adjusting the POTs, as was the case for my Game Cube.

Thank you.

[paulera]

Fixed my system!

Basically you can use an oscilliscope to get the pattern right while adjusting the "E/F, B" pot. and once you get it to boot you can fiddle with the tracking gain "T. Gain" pot.

-Segasonicfan

This is golden info. Since my CDX is booting and playing stock games just fine, my guess, by reading this is that I should only try and change this T.Gain pot. I'll measure it as it is with a multimeter and then try messing with it. Hope that works.