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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

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.

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!

And i need another info about a C54 ceramic cap what's the value?

https://www.smspower.org/uploads/Development/PALMasterSystemIIICBDM4JrPAL-Compon...

https://www.smspower.org/Development/SegaMasterSystemIIServiceManual#PartsListFo... says 0.1uF 16V for the PAL RF version, but 100uF 10V for the RGB version.

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

Author	Message
kaini Joined: 24 Aug 2012 Posts: 15 Location: Italy	Sega Master System 2 CXA1145P wire bridge Posted: Thu Jan 07, 2021 1:13 pm
kaini Joined: 24 Aug 2012 Posts: 15 Location: Italy	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

Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	Posted: Fri Jan 08, 2021 2:08 am
Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	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.

kaini Joined: 24 Aug 2012 Posts: 15 Location: Italy	Posted: Sun Jan 10, 2021 10:50 am
kaini Joined: 24 Aug 2012 Posts: 15 Location: Italy	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!

kaini Joined: 24 Aug 2012 Posts: 15 Location: Italy	Posted: Sun Jan 10, 2021 11:08 am
kaini Joined: 24 Aug 2012 Posts: 15 Location: Italy	And i need another info about a C54 ceramic cap what's the value? https://www.smspower.org/uploads/Development/PALMasterSystemIIICBDM4JrPAL-Compon...

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14732 Location: London	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.

kaini Joined: 24 Aug 2012 Posts: 15 Location: Italy	Posted: Sun Jan 10, 2021 1:34 pm
kaini Joined: 24 Aug 2012 Posts: 15 Location: Italy	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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