Problem with my Sega CDX

[darkshadow1804]

hi there!
i recently got a Sega CDX from a guy, that told me the console runs just perfect, but not playing the sega cd games sometimes...so i remembered that that is caused by insufficient amps (he used a 1200mA 9v transformer instead of 1500mA or higher)...so i plugged my 2000mA 9v one into it, and tried with a genesis game first (SONIC 2, yay!)...the genesis part works flawlessly, while the LCD screen says GAME on it...but when i power it on without a cartridge, it's supposedly to run in sega CD mode, the CD inside spins a bit, but nothing happens, just a plain black screen (and hissing noises on the headphone jack), and the LCD displays GAME only, not ACCESS...so i thought that the cd drive could be faulty, but it isn't, because i put in a couple of AA batteries and tried the CD player mode, and works very well without having ANY difficulty to read an audio CD, so...
what the problem could be?

i post a video to show you the problem:


http://www.youtube.com/watch?v=h5ttvUN36mA

could be the 12Mhz CPU, the BIOS or a DRAM chip dead? or just as simple as a faulty resistor or capacitor?
help! i don't want to get it back to the guy that sold it to me without having a clue of what is wrong with it and being able to fix it :(

thanks in advance!!!

[atarifanboy1980]

It have to be a laser problem . You have to replace it .

[darkshadow1804]

a laser problem? hmmm...but why can i play audio cds with the batteries?

[atarifanboy1980]

a laser problem? hmmm...but why can i play audio cds with the batteries?

Let say you have a ps3 right that play all ps1,ps2 ,and ps3 games. And it having problems playing ps1and ps2 games right but it can play ps3 games . see ps1 is formatted a cd-rom game right . Now for the ps2 games is formatted dvd right . If you have that problem it have to be the laser going out and needs to be replaced . Simple as that .

[darkshadow1804]

could be,
so that is the reason the sega cd mode just gives me a plain black screen, not the bios animation nor nothing else? D:

[atarifanboy1980]

could be,
so that is the reason the sega cd mode just gives me a plain black screen, not the bios animation nor nothing else? D:
That could be it . I mean usually a laser don't last long . lol . It would be the same for any game system that have a laser to me . Myself never had played a Sega CD or CDX system so I don't know much about it . I hope that I help you out some .

[Tokimemofan]

Let say you have a ps3 right that play all ps1,ps2 ,and ps3 games. And it having problems playing ps1and ps2 games right but it can play ps3 games . see ps1 is formatted a cd-rom game right . Now for the ps2 games is formatted dvd right . If you have that problem it have to be the laser going out and needs to be replaced . Simple as that .

You are misunderstanding how these work, your PS3 example is misguided because a PS3 has 3 Laser Diodes either of which can die individually, a dead 780nm breaks cd-rom (Blue and Black discs CDs) 650nm breaks DVDs and 405nm breaks BluRay (and usually everything else as the ps3 starts it in 405nm mode to check for the presence of a disc) The Sega CDX only has 1 laser. A laser failure also couldn't cause the black screen problem. Check and make sure the bios is good and original, some people like to put a region free bios in these things, if such a mod is done wrong it would cause this as could a lifted pin on any of the surface mount IC chips. It is likely to be a hard to ID failure since there are not many simple problems that would still allow the Genesis and Walkman modes to run while disabling the bios completely. The symptoms are similar to a model 1 that had 4 lifted pins on one of the cpus. Get out a good magnifying glass and inspect every connection on both boards.
Edit: Another note, The BIOS will run without a laser assembly even being present, something I tested when part swapping to ID a broken part on one I had.

[atarifanboy1980]

You are misunderstanding how these work, your PS3 example is misguided because a PS3 has 3 Laser Diodes either of which can die individually, a dead 780nm breaks cd-rom (Blue and Black discs CDs) 650nm breaks DVDs and 405nm breaks BluRay (and usually everything else as the ps3 starts it in 405nm mode to check for the presence of a disc) The Sega CDX only has 1 laser. A laser failure also couldn't cause the black screen problem. Check and make sure the bios is good and original, some people like to put a region free bios in these things, if such a mod is done wrong it would cause this as could a lifted pin on any of the surface mount IC chips. It is likely to be a hard to ID failure since there are not many simple problems that would still allow the Genesis and Walkman modes to run while disabling the bios completely. The symptoms are similar to a model 1 that had 4 lifted pins on one of the cpus. Get out a good magnifying glass and inspect every connection on both boards.
Edit: Another note, The BIOS will run without a laser assembly even being present, something I tested when part swapping to ID a broken part on one I had.

I just thought it might be a laser problem thank you for clearing it up .

[Tokimemofan]

I just thought it might be a laser problem thank you for clearing it up .

Tomorrow I'll pop the lid on mine and see if I can find any leads.
Edit: just opened mine, you should get the BIOS background screen even when the CD daughterboard is missing, on the mother board look for IC numbers 1, 5,9, and 14, they should be in a square arrangement, the bios is IC11, check the area around all 5 of them for any damage. Also check the power supply daughter board, it is possible that one of the lines is damaged. Just a warning before you get out a screw driver, this is easily one of the hardest systems to open for a first timer since you will not be able to see everything you are doing.

[atarifanboy1980]

Tomorrow I'll pop the lid on mine and see if I can find any leads.
Edit: just opened mine, you should get the BIOS background screen even when the CD daughterboard is missing, on the mother board look for IC numbers 1, 5,9, and 14, they should be in a square arrangement, the bios is IC11, check the area around all 5 of them for any damage. Also check the power supply daughter board, it is possible that one of the lines is damaged. Just a warning before you get out a screw driver, this is easily one of the hardest systems to open for a first timer since you will not be able to see everything you are doing.

Is there a way to fix the bios ??

[APE992]

Is there a way to fix the bios ??

Yes. Just keep in mind if you decide to open it you run the risk of breaking some very expensive (and rare) hardware. The soldering isn't hard if you have decent experience with it but all it takes is one wrong move.

[xelement5x]

Also marginally related here, the stock specs for the CDX are 9.5V and 1.5 Amp. You've got enough amperage in your new supply, but you're missing half a volt. This can be an issue with those systems, but the lack of BIOS screen indicates your problem is probably somewhere else.

I just wanted to let you know this since I've heard using an underpowered power supply can kill the laser in these systems.

[shadowkn55]

Also marginally related here, the stock specs for the CDX are 9.5V and 1.5 Amp. You've got enough amperage in your new supply, but you're missing half a volt. This can be an issue with those systems, but the lack of BIOS screen indicates your problem is probably somewhere else.

I just wanted to let you know this since I've heard using an underpowered power supply can kill the laser in these systems.

The lack of half a volt on the power supply shouldn't be an issue. Most consoles from that era run the input voltage through a regulator that drops the voltage to +5v. You can generally use anything between 9-12v but it still needs at least 1.5 amps.

[APE992]

Assuming the CDX has a 7805 voltage regulator inside it wouldn't matter too much. I'd still be concerned about the current due to the fact that those numbers are probably burst and not a sustained output.

[Tokimemofan]

A PlayStation 2 power supply works just fine, it is rated at 8.5v but the amperage is high enough (4x higher than required) to voltage drop to the proper range.

[darkshadow1804]

A PlayStation 2 power supply works just fine, it is rated at 8.5v but the amperage is high enough (4x higher than required) to voltage drop to the proper range.

yup, i used a playstation 2 power supply cuz i heard it works great on the CDX (with its 4 amps), but the results are the same...
and i discovered something, when it gives me the black screen, if i press the reset button repeatedly, often gives me annoying buzzing sounds with a red, light blue, white, green or B/W vertical bars across the screen!!! WHAT THE...!!!

i think i'll have to re-open it again, and yeah, i know it's a bit difficult to disassemble and taking everything apart, but i've done it like...5 times? so it wouldn't be a problem, i'll check the pins of components around the bios one

[raylydiard]

so right once i had this fault it was a bad pad on the bios had rust on it.

[Tokimemofan]

Assuming the CDX has a 7805 voltage regulator inside it wouldn't matter too much. I'd still be concerned about the current due to the fact that those numbers are probably burst and not a sustained output.

I do not see a 7805, just 2x B1267 transistors and 2x unknown component s30-03. I think the voltage regulator may be made from discrete components, the power socket is on a small daughter-board that seems far over-engineered for it's purpose, there are 4x 470µf capacitors that seem to be for ripple filtering (something that is already done in the MK-4122) and 2 large inductors, it just seems to be doing way too much with too many individual parts. There is also the complete lack of a heatsink that the 7805s are normally bolted to, not that those would actually fit in the case. That may also explain the prevalence of the F1 problem.

[darkshadow1804]

well, the small power supply board seems to be fine and no track is broken or damaged whatsoever
i found a bad capacitor in the CPU board so i replaced it, and cold solder joints on the VPUs (IC9 and IC14), so i decided to re solder very carefully, after a few tries the cold solder turned shiny, but now the genesis part shows a jumping image with a lot of rainbow banding and a lot of hissing noise in the AV OUT (but in the headphone and line out jack sounds perfect)
maybe i'm screwing it up more than fixing it...i'm about to giving up and get it back to the guy...cuz he sold it to me in about $150 (U.S Dollars) saying that works nice, so, i'd get my money back =)

[ScoreAddict]

Hi!

I have a very similar problem with my CDx!

Description over here:

http://www.theisozone.com/forum/viewtopic.php?f=65&t=46155

Maybe some of you can help me?

All the Capacitators have been replaced and the battery is charged at 2.57V (maybe too low?). Power supply is original (Multi Mega or PS2) so it's not that issue.

I'm wondering if the RAM or BIOS could be the issue. Is there any way to enter the BIOS or do a "factory reset" on the console?

[ScoreAddict]

Addendum:

A cheap replacement for the ML-2016 (3V, 25mAh) rechargable battery in this console is the VL- or ML-2020. It is used in the remote control for some BMW-cars - price at about $7-$8 (5 Euro). Should also work for the Sega- and Mega-CDs expansions.

Everyone else on holiday?

[ScoreAddict]

Addendum:

Old ML-2016 rechargable battery replaced with a brand new VL-2020. Issues remain.

So it's not the voltage of the battery.

[ScoreAddict]

Console repaired, all functions restored! :)

The problem was the Sega CD-BIOS not initialising. Basically waiting for Sega CD-components to report back, which they did not do. Hence a startup-screen but no animation playing, hence a black screen after each reset.

The problem was a corroded pin on the 315-5632, which is one of the two Sega CD's ics. These are located on the lower side of the upper pcb.

http://6.t.imgbox.com/K7HiCXPd.jpg (http://imgbox.com/K7HiCXPd)

Most certainly no connection here.

http://7.t.imgbox.com/6b40Ssnu.jpg (http://imgbox.com/6b40Ssnu)

It's not the greatest paint job, but it did the job. ;)