Master System 1 no power

Dear all,

Recently I bought a defective SMS1. Upon opening I saw a few things missing like the 7805 IC. Easy fix is what I thought. Upon placing a new one the board still did not turn on. Replaced almost every capacitor that had continuity on it but without avail. Between I and C I measure continuity. Between C and O I measure a short circuit. I have been checking everything to see nothing is touching ground but all seems ok.

Any ideas

I have following board.
http://www.smspower.org/uploads/Dev...nent.jpg?sid=fb7cb45f39b25c7d33d83915a9629fe9

I can make photos of my own board if necessary.

Greetings,
Michiel

 

You might have installed the 7805 backwards from the sound of it, as the front of the 7805 actually faces the right-hand side of the system on early boards such as yours. Also make sure your new 7805 has a good heat sink mounted on it if you didn't get the original heat sink with yours.

 

I installed it correctly, the measurement was without the 7805 IC. Or is it normal to have such a reading without the IC?

 

Sry if this is a noob question but what do you mean by ' I and C I ' and ' C and 02 ' ?

 

Between I (input) and C (common), I (me) measure continuity. Between C (common) and O (output) , I (me) measure a short circuit.

Sorry, English is not my mothertongue.

 

Then it sounds like you have a short between ground and the voltage output somewhere along the line. I know you said that it didn't, but there might be just a fleck of solder somewhere that can throw everything off and cause the problems you're having.