Colecovision No Audio or Video

[kf6rcp]

HI! I finally found out what was wrong with my system. I checked voltage with it powered up and found that the +5v was dropping to .228 volts when the switch was put to on. I unplugged the power supply from the board and i put a load on the +5 pin and ground with a bulb and it surely dropped so basically a defective power suppy. Made a temporary +5v and the system work perfect. Anyone knows where to get a schematic of the power supply? Thanks!

[FABombjoy]

It's probably a 7805 regulator or something of that sort. There shouldn't be too much to the inside of that supply, just crack it open and see what you see.

[kf6rcp]

yeah I got a 7805 but I am debating if I should jsut install it using the 12v as the inout voltage and jsut cut the 5v wire and connect it to the 7805. Have you cracked open a power supply? I was hoping there is a scew under the metal label but there was none. Let me know what your expirience is on this?
Mike

[FABombjoy]

I've never opened one, but in my experience most power supplies like that are glued around the edge. Sometimes you can hit them with a hammer & break the glue loose, sometimes you just gotta bust 'em. But hey, duct tape is available in black

[InsaneDavid]

I've never opened one, but in my experience most power supplies like that are glued around the edge. Sometimes you can hit them with a hammer & break the glue loose, sometimes you just gotta bust 'em. But hey, duct tape is available in black

I go at it with a cutoff wheel on a dremel myself, after a couple slices the two halves seem to pop right apart with most power supplies.

[FABombjoy]

Well... I guess that could work too, but the hammer is such an underutilized diagnostic tool

[kf6rcp]

I opened up the power supply with the dremel and everything went good. Found a couple of regulators and power transistors that might be at fault. Regulator is a CA723CE and power transistor is TIP41A. Not really sure which is bad so I ordered both. I have a feeling its the voltage regulator. Any ideas?

[FABombjoy]

Sounds like there isn't much inside to troubleshoot, really. Maybe diode test the TIP41 first and see if it can be ruled out immediately. As long as you have the parts, might as well change all of them just for fun.

[kf6rcp]

Thanks! I did get the parts in and I first changed the CA723CE and still did not work. So, I changed the TIP41A. TIP41A did fix the the problem and now I'm playing with it. Thanks for all the input.