Author Topic: Sega Genesis VA2 Board Rev. SMD Component Replacement  (Read 1817 times)

0 Members and 1 Guest are viewing this topic.

Offline DHeth

  • Contributor
  • Posts: 9
  • Country: us
Sega Genesis VA2 Board Rev. SMD Component Replacement
« on: August 22, 2016, 03:22:44 am »
Hello, I'm pretty new to electronics repair and I've been repairing Old Video games consoles mostly. I have been able to fix everything so far but I'm stuck on this one.

I have a Sega Genesis VA2 Board Rev. that outputs garbled video, the sound output is fine.

https://goo.gl/photos/JxpuiPovkzVbCTSU7

I went inside to look for for bad solder joints when I discovered this : https://goo.gl/photos/oqYceUjPzATbUrmy8

the small (light beige) ceramic component in the picture. It appears to be chipped in half, or blown do apart ? can these explode?

(zoomed out) https://goo.gl/photos/z4nwXXsQkXuBfdKj6

It think it is a surface mount ceramic capacitor but I'm not sure. I'm hoping replacing this part fixes it , however I can't identify it to know the specifications to buy a replacement part.

http://www.mouser.com/Passive-Components/Capacitors/Ceramic-Capacitors/_/N-5g8m/

This is the first part I have had to replace that is not labeled or easily identifiable.

I tried following the traces on a schematic but one of the pcb pass throughs was underneath an IC and I could no follow it.
http://gamesx.com/wiki/lib/exe/fetch.php?media=schematics:genesis-2-md-2-schematic-va1-1_of_4.png
 

Offline nidlaX

  • Frequent Contributor
  • **
  • Posts: 649
  • Country: us
Re: Sega Genesis VA2 Board Rev. SMD Component Replacement
« Reply #1 on: August 22, 2016, 03:33:52 am »
You should look at the circuit board layout diagram in the service manual, find the identifier for that capacitor, and then match it to the correct part on the parts list. The layout diagram will show where each part is located precisely on the PCB.
 

Offline DHeth

  • Contributor
  • Posts: 9
  • Country: us
Re: Sega Genesis VA2 Board Rev. SMD Component Replacement
« Reply #2 on: August 22, 2016, 03:57:16 am »
 that one diagram is all I have been able to find for the Sega Genesis MK1 and I'm not even sure it is the correct board revision.  :-// For some reason I can find plenty of Service manuals for the Sega Genesis MKII though :(

What are the primary specifications needed for choosing a new Capacitor, Capacitance and voltage?


The capacitor I'm looking at replacing:
It is surface mount.
It is ceramic.
I don't think it is polarized.
Voltage rating? As long as i'm equal to or higher than the original I'm ok ?
Capacitance ? There is probably no way to measure the capacitance since the part is damaged.

I'm not sure what changing the capacitance rating does, too low and It can't store enough energy? Too high and it ____ ?




I found this list of all the electrolytic(only) capacitors in the Genesis Mark 1 VA3, not really helpful since it doesn't list the ceramic capacitors though.




Label
        Voltage Rating (V)
                Capacitance (uF)
----------------------------
C1   16   220
C13   16   10
C23   10   100
C24   10   100
C30   16   10
C31   16   10
C32   10   220
C38   16   10
C4   10   100
C40   50   1
C41   10   10
C42   50   1
C43   16   10
C44   50   1
C49   10   100
C5   16   10
C50   10   220
C51   10   220
C52   10   100
C53   10   100
C55   16   10
C57   16   10
C58   50   1
C59   16   47
C60   16   47
C61   50   1
C62   50   1
C63   16   47
C64   16   10
C65   10   47
C66   10   47
C67   10   47
C68   10   47
C71   16   10
C72   16   10
C74   10   100
C79   16   100
C86   10   100
JP1   10   47
« Last Edit: August 22, 2016, 04:03:21 am by DHeth »
 

Offline CJay

  • Super Contributor
  • ***
  • Posts: 3304
  • Country: gb
  • M0UAW
Re: Sega Genesis VA2 Board Rev. SMD Component Replacement
« Reply #3 on: August 22, 2016, 01:26:54 pm »
They generally don't explode, looks like mechanical damage.

If that were my board I'd remove the other pale beige capacitor and measure it.
M0UAW
 

Offline DHeth

  • Contributor
  • Posts: 9
  • Country: us
Re: Sega Genesis VA2 Board Rev. SMD Component Replacement
« Reply #4 on: August 23, 2016, 02:50:34 am »
Looks like I get to learn a new function of my (junk)  :-DMM multimeter , it has two sockets on the FCx setting for capacitors. I take it the capacitor has to be isolated to get an accurate reading of capacitance  .  :-/O

I know replacing the capacitor with a higher voltage rated one is ok.
What are the drawbacks if I exceed the capacitance of the original capacitor, it will draw more voltage initially to charge it up ?
« Last Edit: August 23, 2016, 02:55:43 am by DHeth »
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf