Sega CD systems repair thread

[Bizous]

Yikes, you're going to need to do a full recap and other work in addition to that part. That is simply a resistor array, very easy to replace. Its just 4x 4K7 resistors.

Thank you for your reply Segasonicfan .

I ordered all the capacitors to replace them. ( I am waiting for the order )

Met I can not find this resistance ALPS 472.
Can you show me which ones I have to buy to replace it .

Sorry for my English

[segasonicfan]

Thank you for your reply Segasonicfan .

I ordered all the capacitors to replace them. ( I am waiting for the order )

Met I can not find this resistance ALPS 472.
Can you show me which ones I have to buy to replace it .

Sorry for my English

Hi, no problem. I assure you my French is much worse than your English (and your English is quite good by the way!)
that's good that you ordered the capacitors. You will also need to clean the board thoroughly with isopropyl alcohol.
I can look up the part for you at a distributor, but I don't know which one you would use in France. here in the US we tend to use Mouser or Digikey. I think they would ship internationally but I'm not sure.

can you take a measurement of the dimensions of the part (L x W?) that will help too.

[Bizous]

Hi, no problem. I assure you my French is much worse than your English (and your English is quite good by the way!)
that's good that you ordered the capacitors. You will also need to clean the board thoroughly with isopropyl alcohol.
I can look up the part for you at a distributor, but I don't know which one you would use in France. here in the US we tend to use Mouser or Digikey. I think they would ship internationally but I'm not sure.

can you take a measurement of the dimensions of the part (L x W?) that will help too.

lol, thank you very much
I train in English looking at the series in Original Version,
Do you want to watch French series to learn French ?

The size of the ALPS 472 parts
Length : 6,5 Millimeter
Width : 3,5 Millimeter
Height : 0,5 Millimeter

Thank you for your help

[segasonicfan]

the part is actually surprisingly difficult to source. most likely cuz it uses a larger package type than what's manufactured today. something like this would work well though if you just use half of the resistors, because it has 8 instead of 4:

https://www.mouser.com/ProductDetail...2qMorsAV5v0%3D

also, I took a look at the schematic and found the part that you're replacing. Its good to have for reference.:

Screenshot_20190322-203924.jpg

keep in mind, you're still going to have to replace all the capacitors, do a lot of cleaning with isopropyl alcohol and possibly fix traces as well.
you can see this video I made about how to do that with the Sega Game Gear, for a proper way to do capacitor replacement and cleaning:

https://m.youtube.com/watch?v=fbum0CE2T7o

[Bizous]

the part is actually surprisingly difficult to source. most likely cuz it uses a larger package type than what's manufactured today. something like this would work well though if you just use half of the resistors, because it has 8 instead of 4:

https://www.mouser.com/ProductDetail...2qMorsAV5v0%3D

also, I took a look at the schematic and found the part that you're replacing. Its good to have for reference.:

Screenshot_20190322-203924.jpg

keep in mind, you're still going to have to replace all the capacitors, do a lot of cleaning with isopropyl alcohol and possibly fix traces as well.
you can see this video I made about how to do that with the Sega Game Gear, for a proper way to do capacitor replacement and cleaning:

https://m.youtube.com/watch?v=fbum0CE2T7o

Thanks for your help Segasonicfan
As soon as I received my order, and start repairing it.
I will give you news.
Thanks again

[seat safety switch]

I recently repaired a CDX with similar symptoms. It looks like a VRAM issue. If you get to TMSS then your 68K and connections are likely fine. I vote that its your MSM54C864-10 (IC192) and / or shorted connection issues to it with the 315-5660. My CDX would load the sega logo and glitch out similarly. It was that chip, and a short to GND on the VRAM bus (a dead 315-5660 pin yuck).

Thanks for the reply. I was hoping it might be the VRAM because it's difficult to source a replacement 315-5660 VDP (all of my "for parts" Genesis 2 have an annoying habit of getting fixed).

How did you find the short to GND on the VRAM bus? I have a slightly corroded pin on the VDP from some kind of goo damage, but it's on the DMA pins and they are continuous with the 68K and not shorted with each other.

I did a quick continuity test from all the pins of the VRAM chip to GND but didn't find anything with the machine at rest.

The VDP is getting noticeably warmer to the touch than the other chips but I wouldn't call it "shorted hot."

[segasonicfan]

The VDP is getting noticeably warmer to the touch than the other chips but I wouldn't call it "shorted hot."

It is very risky to be powering on a damaged system like this. The longer you leave it on the more risk you run of more shorts and damage to the ICs.

You have a very tricky repair here. If theres no obvious VDP shorts than you have a Lot of testing to do. It's not something I could really troubleshoot online, but if you want to send it in maybe we can work something out. However, these kinds of repairs are difficult and extremely time-consuming (ie expensive).

Honestly, if you have any sort of day job I would recommend just selling this one for parts. I might be interested in buying it from you and try to repair it in my downtime. Ive had repairs like this take 10+ hours so its hard to just offer quick advice for it.

[vintagegamecrazy]

Does anyone know where I could find a replacement laser motor for a Sega CD model 2? It is the model with the sockets on the disc drive and not the ribbon cable. The motor is very noisy and has lots of friction when spinning.

[segasonicfan]

Does anyone know where I could find a replacement laser motor for a Sega CD model 2? It is the model with the sockets on the disc drive and not the ribbon cable. The motor is very noisy and has lots of friction when spinning.

I don't know off the top of my head, but posting a picture or model number (or both) would certainly be helpful in your quest.

[TrekkiesUnite118]

So I have a problem, I attempted to recap my Model 2 Sega CD which has the Funai Board and it's gone horribly wrong. First of all I had multiple caps where the pad came off when I desoldered the old Cap. I had the temp of my iron at about 275F when this happened which I didn't think was too hot for that, but when it first happened I turned it down to abut 250F and it still kept happening. So I'm not sure what happened there. In the instances it happened I checked with a flashlight to see where the traces where and made patches as best I could when necessary.

The second issue was the recap kit I ordered from Console5 seemed to have misplaced a 47uF for a 470uF cap. So that cap I did not replace yet as I'm waiting on the 470uF caps I ordered to arrive. However that asside the system is behaving poorly. First is the drive is making a horrible clicking noise now. It appears to be because it's trying to go past it's gears when it reaches the inner most part of the disc. This doesn't appear to be limit switch related as after checking that with a Multimeter it appears to be behaving correctly with the expected Ohm readings when it's opened and closed as well as the proper voltage readings on the test points on the board. I've recorded a video of the clicking here:



If I turn VR401 slightly counter clockwise however, I can get this clicking to stop. At that point the system will read the disc and attempt to play it but it skips horribly. My Multimeter is able to read frequencies so I did the test to check VCO. It looks to be in spec with a reading of 4.320MHz, however I noticed when it skips this reading jumps up for a split second to about 4.5MHz. I've checked all the solder points and patch areas I had to make for continuity and they appear to check out, so I'm at a loss at this point. Is my board pretty much shot at this point or is there anything I can do to try and fix it?

EDIT:

Nevermind, after touching up some solder points it's now in a state of not even booting. It just freezes on the planet screen with the bios version and no sound. There's a handwritten note in the service manual for that which states it's a faulty IC401 which is the Sony CXD1167Q. Another note also mentions distorted CD Audio but ok PCM as pointing to this issue. That's similar to earlier behavior I saw as I could still play some games, but once it tried to play CD audio or an FMV it would be distorted/start skipping and would then crash.

So I think it's officially dead short of swapping out that IC.

[chrisw80]

So I have a problem, I attempted to recap my Model 2 Sega CD which has the Funai Board and it's gone horribly wrong. First of all I had multiple caps where the pad came off when I desoldered the old Cap. I had the temp of my iron at about 275F when this happened which I didn't think was too hot for that, but when it first happened I turned it down to abut 250F and it still kept happening. So I'm not sure what happened there. In the instances it happened I checked with a flashlight to see where the traces where and made patches as best I could when necessary.

The second issue was the recap kit I ordered from Console5 seemed to have misplaced a 47uF for a 470uF cap. So that cap I did not replace yet as I'm waiting on the 470uF caps I ordered to arrive. However that asside the system is behaving poorly. First is the drive is making a horrible clicking noise now. It appears to be because it's trying to go past it's gears when it reaches the inner most part of the disc. This doesn't appear to be limit switch related as after checking that with a Multimeter it appears to be behaving correctly with the expected Ohm readings when it's opened and closed as well as the proper voltage readings on the test points on the board. I've recorded a video of the clicking here:



If I turn VR401 slightly counter clockwise however, I can get this clicking to stop. At that point the system will read the disc and attempt to play it but it skips horribly. My Multimeter is able to read frequencies so I did the test to check VCO. It looks to be in spec with a reading of 4.320MHz, however I noticed when it skips this reading jumps up for a split second to about 4.5MHz. I've checked all the solder points and patch areas I had to make for continuity and they appear to check out, so I'm at a loss at this point. Is my board pretty much shot at this point or is there anything I can do to try and fix it?

EDIT:

Nevermind, after touching up some solder points it's now in a state of not even booting. It just freezes on the planet screen with the bios version and no sound. There's a handwritten note in the service manual for that which states it's a faulty IC401 which is the Sony CXD1167Q. Another note also mentions distorted CD Audio but ok PCM as pointing to this issue. That's similar to earlier behavior I saw as I could still play some games, but once it tried to play CD audio or an FMV it would be distorted/start skipping and would then crash.

So I think it's officially dead short of swapping out that IC.

Damn between this and Grandia for Sega Saturn you have your hands full.

I can't wait for the Mega SD, won't bother ever repairing Sega CDs once that launches.

[vintagegamecrazy]

You may want to try setting the soldering iron at 300 to 315 degrees Celsius. I found that To work really well in soldering. If the solder pads only lifted and didn't tare you could remove the capacitors and get some high heat epoxy and reglue them down. As long as you can find the IC to replace it should be salvageable.

[Madness Hero]

Howdy all, I recently aquired a model 1 CD. I finally got all my cords propper and everything seems to be working great except the disc drive. When powered up and opened regardless of if u put a disc in when you hit close it starts to close stalls slightly and then closes and then immediatley opens. Then if i power the system off and then back on the tray closes and stays shut until I press the button and thus repeats the cycle. Now I've come to understand changing the belt is usually the go to fix but I'm curious if it could be something else since it stays closed after the power on and off. Hoping an O.G. can get on here n give me the down low.

Edit: I forgot to mention this is a JVC drive, after doing a lil digging I noticed my disc tray is missing the gold screw at the back right hand corner of the disc tray is this screw intended to engage the gear sooner? And can some one take a picture of the screw or tell me if it's necessary and if it's the same size as the RF shield screws or larger?

[TrekkiesUnite118]

You may want to try setting the soldering iron at 300 to 315 degrees Celsius. I found that To work really well in soldering. If the solder pads only lifted and didn't tare you could remove the capacitors and get some high heat epoxy and reglue them down. As long as you can find the IC to replace it should be salvageable.

Some of the pads I wasn't able to salvage, but the trace is easy enough to see where it goes so making a patch is doable. The problem is at this point with the IC and all is that it's way beyond my skill level.

[Firebrandx]

Hoping experts on M1 Sega CD drives (USA) can shed some light on this, but I found I have to lift the front of the M1 SCD up about 25 degrees from level in order to prevent PCM audio/video skipping. Even CDDA was getting hit a little bit, but PCM was skipping like crazy. Tilting the console 25 degrees from the front removes ALL skipping. Ive already done a recap and replaced the drive belt. I'm thinking this is some sort of issue with the laser. I looked at the drive spindle and nothing appears to be wrong there that I can tell. Everything else on it works like a champ.