Colecovision Power Brick voltage issue

[Niki]

So, I have a colecovision that has been giving me nothing but problems one after the other. I found out that my power brick has gone out and since I have a lot of spare capacitors/resistors/regulators, etc. I actually would prefer to attempt to fix it first before tracking down a new one and also to be able to have the experience of fixing it.

 

The situation was that one day, it just wouldn't turn on, I would just get static that would get better or worse as I adjusted the power connection. So, I took out my voltage meter and found that on the 12V pin, I was only getting 2.35 Volts, all other pins were fine. So, I cracked the thing open with intent to change out the 12 V regulator. As I was testing it to see which one of the regulators was acting up, I found that for whatever reason, the readings I would get from the 12V regulator were inconsistent. Sometimes, I would get 2V, other times, it would read properly at 12V and other times, it would just jump around. So, I just decided to change out the regulator anyway and now, it's consistently reading 17V, so I bet something else is messing up in there or that I got a faulty part (It was bought way too long ago to return the part but it was new, as in I didn't scrap it from another unit.)

 

I currently just put it away as I was frustrated with it. I probably will be able to figure it out after a while, but if anyone can point me in the right direction to save me some time, that would be very much appreciated. As I stated in the last post about the same colecovision, I have some basic electronics knowledge but not a lot. Kind of learning as I go here.

[+Stephen Moss]

What voltage do have you go going into your regulator? If it is about the same (17V) then there are two possibilities. One is that you have the inserted the regulator back to front as many have a protection diode across them which will conduct under this situation hence the output voltage will be roughly 0.7v less than input voltage. The other is that the ground (0V) connection to the regulator is open circuit and the regulator cannot regulate with no current flowing through it to ground.