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MD Sega CD Model 1 Capacitor Differences

supersega

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Hi folks,

Long time no talk. :D

I have been sent a few Sega CD model 1 boards to repair after someone else ripped a lot of vias and couldn't fix the rotting on the traces due to the leaky SMD caps. So far I have made a list of all the caps on the sub-board that must be fixed, and I cannot find a few of them. This may just turn into a "supersega, you need glasses" thread but I have looked everywhere and cannot find what C8 and C9 are connected to in the service manual schematic. The vias have been ripped off the board so I can't backtrack it easily, but I have a theory that I wrote down. I also noticed that C5 has a difference from the service manual on the Sega Wiki, where my negative end goes to R37 and not the resistor specified within the manual. See my spoiler below for the full list of caps...

Sub Bd

C1: good

C2; + goes to IC3C Pin 8, - goes to R17

C3: + goes to PIN1 IC1, - goes to point for neg.

C4: + goes to top, - goes to bridged pins.

C5: + goes to IC4P1, - goes to R37 (NOTE), opposite side of what goes to C33+.

C6: good

C7: + goes to ?, - good.

C8: + goes side of R22, - goes to via (?)


C9: + goes to LC7883KM pin 27, - goes to point for neg (SURFACE)

C10: Surface

C11: + goes to LC7881M pin 16, - goes to ground

C12: Surface / + goes to LC7881M pin 2, - goes to ground.

C13: Good

C14: Good

C40: Positive to pin 5 on LC7883, - to ground.

C41: + surface, - good.

C42: + good, - ground (surface?)

C43: good.

I have a LOT of work cut out for me, now that I'm looking back... but I'd be really appreciative if someone could confirm/deny my findings who knows this sort of thing better than me, or may have a set of better eyes. :)
 

Tokimemofan

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C8+ to R22
C7+ to R23
The negative end connects to EM2, not sure which pins but it is easy to bypass a bad trace on these the 2 vias below and left of r20 are for the negative of C8 and C7. Easiest bypass for c8 is to bridge the negative trace connecting 2 vias near the r23 label
Edit: corrected the capacitor number
 

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supersega

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I think I catch you on that. Thanks Tokimemofan!!
 
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