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  • Joined: 29 Nov 2016
  • Posts: 4
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Add missing video encoder in French Master System 1
Post Posted: Fri Dec 02, 2016 12:36 pm
Last edited by Lenwë on Sun Dec 04, 2016 2:55 pm; edited 1 time in total
Hi

I have a problem with my Master System 1 and my LCD TV.

I have a Model 3005-09-B and the console is connected to the TV with the RGB adapter 3085 SCART cable which is the model for France.

Unfortunately, my TV (a Sony Bravia KDL 40v3000) doesn't seem to properly recognize the native RGB + C-sync signal and I experience severe synchronization issues.

I tried a few things, such as adding a LM8118 on the Csync, switching the console from 50 Hz to 60Hz, none fixed the problem (however, switching to 60Hz dramatically reduced the glitch, it's almost playable now).

The problem with the french consoles is they lack the video encoder components so it's impossible to do a composite/s-video out mod to work around the problem.

Here is a picture of my motherboard in attachment, a SEGA M4 POWERBASE/NTSC 837-6700

As you can see, the IC9 and a bunch of passive components are missing.

What I want to achieve is to draw up the list of those missing components since they are all standard and easy to find (even at local electronics stores) to add the missing video encoder and allow video out mods on the french consoles.

Here is the list of missing parts.
C51
R50

C33
R35
C29

C27
C22
L32
R27

R26
C28
R24

-----

IC9

-----

L31 (component under CA1)
C32
R30
R40
C39 *      (already present on some motherboards)

R36
C37
R15

C18
C17
R16
R6

C12
C13
C14
R7

R9
R10
R11
R8

L50
C143
R145
R144

C20
C21


I noticed that the components of some other revisions such as the 837-6629 (found on this website as well) are 99% identical by comparing the pictures of the mainboard.

Unfortunately, I wasn't able to find the parts list for revision 837-6700 or 837-6629 from 1988 (the only one I found is on this website and it's for an older version from 1986).

If one of you guys have a Master System 1 with a M4 POWERBASE/NTSC motherboard of revision 837-6700 or 837-6629, would you help me retro-engineer the missing parts list ?

Thanks :)
IMG_1328.jpg (2.13 MB)
SEGA M4 POWERBASE/NTSC 837-6700 motherboard without video encoder
IMG_1328.jpg
IMG_1330.jpg (2.18 MB)
SEGA M4 POWERBASE/NTSC 837-6700 motherboard without video encoder (back)
IMG_1330.jpg

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  • Joined: 23 Apr 2014
  • Posts: 131
  • Location: NYC
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Post Posted: Sat Dec 03, 2016 2:47 pm
These are all the pics I have at the moment. All my consoles are in storage, so I can't take new ones for awhile...sorry about that.

http://www.retrorgb.com/files/SMSMotherboardPics.zip
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  • Joined: 19 Oct 1999
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Post Posted: Sat Dec 03, 2016 3:49 pm
Lots of images at http://www.smspower.org/Development/HardwareImages-Index
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  • Joined: 30 Jun 2016
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  • Location: Melbourne, Australia
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Post Posted: Sun Dec 04, 2016 12:43 am
If I can ask a dumb question - Why not build an external encoder, rather than re-adding one back into the French SMS?

It'd be a whole lot less fuss, and be flexible across multiple systems.
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  • Joined: 13 Jan 2024
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Post Posted: Sat Jan 13, 2024 9:41 pm
Please be careful with those values, I went through all the images I could find online and came to following numbers, also I give up on the chokes (L31,L32,L50) and simply put a jumper there. It works for me. so maybe someone would like to use it as well.
I had a biggest problem with c18 so I used values from the CXA1145 diagram.

C12   100nF
C13   100nF
C14   100nF
C143   100nF
C39   100nF
R16   1 k
R35   1 k
R40   1 k
R30   1.3 k
R144   10 k
R15   10 k
C21   100nF
C17   100pF
C27   100pF
C29   100pF
C32   100pF
C20   100uF   10V
C51   100uF   10V
C33   10nF
C28   10uF   10V
C18 (??)   1uF
C37   1uF 50V
R06   2.2 k
R07   2.2 k
R08   2.2 k
R27   2.2 k
R36   24 k
R09   4.7 k
R10   4.7 k
R11   4.7 k
C22   47pF
R145   8.2 k
IC9   CXA1145
R24 (?)   11
R50 (?)   11
R26(?)   33 (or something bt. 23 – 43)
L31   
L32   
L50   

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