Japanese mega CD..

Hi again,

bought an ebay Japanese mega CD model 1, not working, so it was missing a ribbon cable, so I replaced that, now the thing is it behaves the same with 2 different drives, with American drive and European drive (its own drive came without laser pickup), it just spins and spins with red light of access only works a little at first then goes ..

so its quite obvious to me that it has nothing to do with laser itself mainly that the European mega cd drive is 100% working.. i noticed that some caps or all on main board are having such bad cold rusty solders, can they cause this?

thnx in advance

 

Yes! change the caps. they are awefull. and also make sure the ac paths of the caps have continuity. corroded mega cds suck!

 

thanks alot , ill try it today , while watching Sweden vs Swiss

 

update , replaced all caps, was about to kill it , found that i dislocated one cpu leg which i had to return to bring it back to work,

its the same, only checking disk for ever , i was able to make it read only 1 audio cd , only 1, no other audio read, no games as well, and it behaved the same, its obvious that its something with mb not cd drive, also cd+g didn't give any graphics when i played the audio disk which works... what could be? it looks like thats y they sold this

 

well that sucks. I think there are several revisions of the mb. one with masked traces and one with visual traces. i guess you have one with hidden? they are the worst to troubbleshoot. I would suspect a corroded trace somewhere.
Time to start beeping. and checking voltages on all ICs?

where the caps hard to remove? whit the solder turned to almoste steel?

 

Probably need to make sure it's calibrated properly, the previous owner may have messed with the pots. It came missing its laser and ribbon cable so who knows what's be done to it. Also, u have introduced a different laser assembly so that may be out of calibration anyway. The fact that it reads an audio disc but fails on games suggests this.

There are 3 pots. Frequency, EF and tracking. U will need a professional calibration disc and oscilloscope.

 

well ya it was hard to remove, even on 500 degrees temp with flux, i will try to see traces.

well i tried 2 other different drives, one of them is EU mega cd drive which has 4 potentiometers on board and 1 on laser... also identical behavior.. identical, starts with a good spin and sound, then goes lost ,, anyways i will give it a try , i don't have an oscilloscope at home , so i will do it flintstone way..

 

ok , after tweaking and from my experience from several consoles, i would definitely say that it has nothing to do with pots or tweaking, now the point is , which solder of main ics or even cpu is not good .. i couldn't see any bad traces..

 

might still be the pots callibrations. in the meanwhile there is a schematic in the wild. start beeping also did you change the caps on the sound/poworboard?

 

no , i will check them too , and about the calibration as i told you one of the drives was working weeks ago with brand new laser, so it can't be only that..

 

power audio caps are ok , something else is not indeed ... and in Google looks like this issue was reported by others as well ,,,,

 

the bios screen freez is quite common as i understand. And the wont play games but audio cds also as a recall. And the only solution that I have seen is to fix broken/corroded traces or bad vias.

and they relly are a pain to diagnose. but the service manual with schematic can be quite a help. Just to se connections between ICs.

A logicprobing might also help.
checking highs anf lows on the main ASIC and the rams

cant think of anything else right now.

 

thanks alot really, I will see what can be done , its the mb with hidden traces so wont be so easy to trace anything here..

 

well , while this was a dead case to me, I strongly suspected bad solders on the cpu, so i removed it by reworking station hot air, cpu legs are mostly good, so I tried to look on the solder points but they are in very bad condition, so fluxing and soldering will do? rusty some are even disconnected i think..

 

Looks like a lot of points and vias showing rust. IC2 is probably salvageable with solder wick, clean solder and flux. IC1 looks like it has a bad point. Some of the discretes also look cold. This board is turning out to be a labour of love. Good luck.

 

lool, indeed it is

i will check your comments on the points , thanks

 

as a last resort i would remove all electrolyte caps and as much as possible of the components, then run the MB in the dishwasher. I know its controversial but sometimes it works and sometimes you see more of the damages after.

best of luck wathever you do.
I have a borad similar to yours that i work on when im bored.

 

in my case i might work on it on non frequent occasions, to avoid losing my nerves, and thanks for the washing tip

 

i have one more question please, are cpus interchangeable between models/regions?

it might look stupid question but sometimes the case is that you have another board with potentially working cpu to use on a board with possibly bad one.

 

well they should be. I dont see why not. But i actually dont know for sure. anuone else want to chime in?