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View topic - Sega Master System 2 CXA1145P wire bridge

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  • Joined: 24 Aug 2012
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Sega Master System 2 CXA1145P wire bridge
Post Posted: Thu Jan 07, 2021 1:13 pm
Hi, I recently bought a Sega master system 2, I disassembled it and I noticed that in the lower part of the board there is a bridge with a wire that starts from PIN 12 of the CXA1145P to a PIN of the capacitor C39 of what is it treats?

https://images2.imgbox.com/6c/68/L8YuPmHs_o.jpg
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  • Joined: 28 Sep 1999
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Post Posted: Fri Jan 08, 2021 2:08 am
This modification is documented in the SMS2 service manual here:

https://www.smspower.org/uploads/Development/SegaMasterSystemIIServiceManual-8377559.png

It looks like something done during manufacture and is not a repair but rather a correction. According to the schematic one leg of C39 should be grounded:

https://www.smspower.org/uploads/Development/SegaMasterSystemIIServiceManual-1715922A-3.png

I would guess the PCB layout had an error and that pin was left floating, so the modification makes the PCB match the schematics.
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  • Joined: 24 Aug 2012
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Post Posted: Sun Jan 10, 2021 10:50 am
Charles MacDonald wrote
This modification is documented in the SMS2 service manual here:

https://www.smspower.org/uploads/Development/SegaMasterSystemIIServiceManual-8377559.png

It looks like something done during manufacture and is not a repair but rather a correction. According to the schematic one leg of C39 should be grounded:

https://www.smspower.org/uploads/Development/SegaMasterSystemIIServiceManual-1715922A-3.png

I would guess the PCB layout had an error and that pin was left floating, so the modification makes the PCB match the schematics.


Thanks!
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Post Posted: Sun Jan 10, 2021 11:08 am
And i need another info about a C54 ceramic cap what's the value?


https://www.smspower.org/uploads/Development/PALMasterSystemIIICBDM4JrPAL-Compon...
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Post Posted: Sun Jan 10, 2021 12:01 pm
https://www.smspower.org/Development/SegaMasterSystemIIServiceManual#PartsListFo... says 0.1uF 16V for the PAL RF version, but 100uF 10V for the RGB version.
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Post Posted: Sun Jan 10, 2021 1:34 pm
Maxim wrote
https://www.smspower.org/Development/SegaMasterSystemIIServiceManual#PartsListForMasterSystemIIPALVersion says 0.1uF 16V for the PAL RF version, but 100uF 10V for the RGB version.


On my mainboard C54 is 10uF 16v electrolytic capacitor
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