Trying to resurrect a dead Sega Master System

[Chad Tower]

Hi, I'm new to electronics repair and am trying to learn all I can.
I've been reading the FAQ here, and while it's helping me in a very
general beginner's way, I figure coming here and posting can't hurt
either.

The SMS console is dead and was dead when I recently got it. I did a
search here and came across this post:

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&threadm=19990717145317.12878.00001947%40ng-fr1.aol.com&rnum=2&prev=/groups%3Fq%3D%2522sega%2Bmaster%2Bsystem%2522%2Brepair%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26selm%3D19990717145317.12878.00001947%2540ng-fr1.aol.com%26rnum%3D2


This post is basically stating to replace a 7905 component, but NOT TO
REPLACE IT WITH A 7805, even if a Radio Shack employee tells you it's
the same thing. Well, I'm looking at the board under the heat sink
and there is a component here labeled 7805 and it appears as though it
may have been poorly soldered in after the fact. Could this have been
a poor attempt at repairing this thing before it got to me? As I
said, I'm very new to this, but... this looks like it may be the case.
Any advice at all would be highly appreciated.

 

The 7805 and 7905 are 5 volt regulators, BUT the 7805 is a positive
regulator, and the 7905 is a negative one.
So the Radio Shack is full of BS.


"Chad Tower" <tower@gis.net> wrote in message
news:1acd7c9.0403170937.20e01c41@posting.google.com...

Hi, I'm new to electronics repair and am trying to learn all I can.
I've been reading the FAQ here, and while it's helping me in a very
general beginner's way, I figure coming here and posting can't hurt
either.

The SMS console is dead and was dead when I recently got it. I did a
search here and came across this post:


http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&threadm=19990717145317.12878.00001947%40ng-fr1.aol.com&rnum=2&prev=/groups%3Fq%3D%2522sega%2Bmaster%2Bsystem%2522%2Brepair%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26selm%3D19990717145317.12878.00001947%2540ng-fr1.aol.com%26rnum%3D2


This post is basically stating to replace a 7905 component, but NOT TO
REPLACE IT WITH A 7805, even if a Radio Shack employee tells you it's
the same thing. Well, I'm looking at the board under the heat sink
and there is a component here labeled 7805 and it appears as though it
may have been poorly soldered in after the fact. Could this have been
a poor attempt at repairing this thing before it got to me? As I
said, I'm very new to this, but... this looks like it may be the case.
Any advice at all would be highly appreciated.

 

[Chad Tower]

It's good to know the difference... though, since the board I see here
has a 7805 on it... and I found a schematic for the SMS that shows a
7805 in this place... could that post be just as full of BS?

Chad

<oldfogie@earthlink.net> wrote in message news:<Sl06c.88433$JN2.49760@bignews4.bellsouth.net>...

The 7805 and 7905 are 5 volt regulators, BUT the 7805 is a positive
regulator, and the 7905 is a negative one.
So the Radio Shack is full of BS.