Quantcast

Page 49 of 49 FirstFirst ... 394546474849
Results 721 to 733 of 733

Thread: Sega CD systems repair thread

  1. #721
    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert majinga's Avatar
    Join Date
    Apr 2017
    Posts
    145
    Rep Power
    3

    Default

    How do you get some voltage if the fuse is open?


    Tr4 is a darlington transistor. It act as a power switch for the MCD. You must find voltage only on one side when is off, and on both when is on. And about 5V on the base when the MD Is on and nothing when is off.

    About the caps only the smd ones are recommended to change. But, if you wanna go for a full recap Is ok.

  2. #722
    Hedgehog-in-Training Hedgehog-in-Training
    Join Date
    Nov 2019
    Posts
    17
    Rep Power
    0

    Default

    majinga: its resistance, i think not voltage;. setting on my multimeter RX 1K.

    If you look at the picture of the mainboard TR4 looks like brown residu next to it.

    And if i measure resistance on F1, nothing at all. Or am i doing something wrong? If i put my multimeter , one on the left leg of F1 and the other on the right, i should see something on my multimeter no? (when the mega cd is off)

  3. #723
    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert majinga's Avatar
    Join Date
    Apr 2017
    Posts
    145
    Rep Power
    3

    Default

    Quote Originally Posted by SPiET View Post
    ... i should see something on my multimeter no? (when the mega cd is off)
    Correct. The fuse is gone.

    TR4 doesn't look good to me. I will replace it.

  4. #724
    Hedgehog-in-Training Hedgehog-in-Training
    Join Date
    Nov 2019
    Posts
    17
    Rep Power
    0

    Default

    Yep doing an order now for those things.

    Btw TR4, is it just desolder on top? the left and right pins since it isnt attached through the pcb? (sorry pretty new in soldering )

  5. #725
    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert majinga's Avatar
    Join Date
    Apr 2017
    Posts
    145
    Rep Power
    3

    Default

    Quote Originally Posted by SPiET View Post
    Btw TR4, is it just desolder on top? the left and right pins since it isnt attached through the pcb? (sorry pretty new in soldering )
    Sorry, it's not clear to me. What do you mean?
    TR4 is an SMT component. Probably a to-252 or 263. Do you need some advice on how desolder it?

  6. #726
    Hedgehog-in-Training Hedgehog-in-Training
    Join Date
    Nov 2019
    Posts
    17
    Rep Power
    0

    Default

    Yes please since i dont see any pins going through the pcb to desolder it.

  7. #727
    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert majinga's Avatar
    Join Date
    Apr 2017
    Posts
    145
    Rep Power
    3

    Default

    That's because it is a surface mount component.
    I would remove it with hot air. Probably is possible to use something like the chip quick to desolder it, but i would not use this method. Or just two Irons.
    Or you can cut the two little legs, and desolder one piece at time.
    Whterver you choose to do, be careful. The pad under the component can be damaged. You risk to tear it away, and end with more work to do. If you are not confident with this kind of work, i suggest you to do some pratique on some other board first.

  8. #728
    Hedgehog-in-Training Hedgehog-in-Training Kamon's Avatar
    Join Date
    Jan 2019
    Location
    Melbourne, Australia
    Posts
    18
    Rep Power
    0

    Default

    I have an update on my broken mega cd! So, I've been able to get a spare Sega CD main board off a buy and sell group. The issue I currently have is faulty ram/ic chips leading to pcm audio glitches with my current main board. This new main board is the same model no. as the old one ignoring the NTSC bios & timing crystal but has the ram chips needed. While I could just swap the ram out and call it there I've got another idea. The new board is in much better condition so it makes sense to use it instead. Swapping out the bios chip seems easy enough but the real question is what will happen when I slot a pal bios in a board with a 60hz timing crystal? What would happen if I ran a pal game and switched to 60hz on a modded megadrive during gameplay? Are there any advantages to leaving the 60hz crystal in, or will I just get timing issues in pal games? Any insight welcome!

  9. #729
    Outrunner Chibisteven's Avatar
    Join Date
    Aug 2010
    Posts
    537
    Rep Power
    15

    Default

    Quote Originally Posted by Kamon View Post
    I have an update on my broken mega cd! So, I've been able to get a spare Sega CD main board off a buy and sell group. The issue I currently have is faulty ram/ic chips leading to pcm audio glitches with my current main board. This new main board is the same model no. as the old one ignoring the NTSC bios & timing crystal but has the ram chips needed. While I could just swap the ram out and call it there I've got another idea. The new board is in much better condition so it makes sense to use it instead. Swapping out the bios chip seems easy enough but the real question is what will happen when I slot a pal bios in a board with a 60hz timing crystal? What would happen if I ran a pal game and switched to 60hz on a modded megadrive during gameplay? Are there any advantages to leaving the 60hz crystal in, or will I just get timing issues in pal games? Any insight welcome!
    I don't think the crystals are different between NTSC and PAL territories for the Mega CD. The Genesis M68K runs at different clock speeds 7.67 MHz for NTSC and 7.61 MHz for PAL and has different crystals. The Mega CD M68K runs at 12.5 MHz for both NTSC and PAL. The only differences between regions are BIOS and the logos and stickers on the units themselves from what I'm aware of.

  10. #730
    Hedgehog-in-Training Hedgehog-in-Training
    Join Date
    Nov 2019
    Posts
    17
    Rep Power
    0

    Default

    ok thanks for the info.

    Well i would try to desolder it from the top. Starting with leg 1 and 2 and then around it (since there is solder there too).
    Attachment 15254

  11. #731
    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert majinga's Avatar
    Join Date
    Apr 2017
    Posts
    145
    Rep Power
    3

    Default

    Again, no attachment.
    You must melt the solder on each PIN together. Try to bend the single PIN is risky, you can apply too much force on the central pad.

  12. #732
    Hedgehog-in-Training Hedgehog-in-Training
    Join Date
    Nov 2019
    Posts
    17
    Rep Power
    0

  13. #733
    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert majinga's Avatar
    Join Date
    Apr 2017
    Posts
    145
    Rep Power
    3

    Default

    No, still not able to see the attachment.

    Some progress in the repair?

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •