Colecovision component mod

disgraceland · Post by **disgraceland** » Thu Jun 19, 2008 6:51 pm

Got a Colecovision that was working fine (except for crappy video) and did the component mod, which worked out great as soon as it was done, but when I put the console back together it stopped working. Now, in the places on the board where it seems it should have a mighty 12 volts it is showing a puny 2. Ever seen this? Thanks.

Dr. KillGood · Post by **Dr. KillGood** » Thu Jun 19, 2008 7:36 pm

AC adapter might be dieing?

disgraceland · Post by **disgraceland** » Thu Jun 19, 2008 7:41 pm

Tried 2 different power adaptors, both tested 12v fine, and the board has 12 at the switch, but is losing it somewhere.

Dr. KillGood · Post by **Dr. KillGood** » Thu Jun 19, 2008 7:58 pm

disgraceland wrote:Tried 2 different power adaptors, both tested 12v fine, and the board has 12 at the switch, but is losing it somewhere.

Perhaps some solder fell onto some leads and is connecting them where they should not be?

GonzoMPM-1 · Post by **GonzoMPM-1** » Wed Jul 23, 2008 5:07 pm

It may be that your TV is touchy on voltage and impedance matching.

The reference schematic in the datasheet for the chip Coleco uses in the daughterboard in that RF box for mixing signals requires, in a composite out configuration, that there be a capacitor and resistor after the transistor.

I presume the capacitor (47uf works) removes the DC component from the signal, and the resister (75 ohms) provides the impedance match.

See if it works for you.

Then check your power switch and motherboard connections, not to mention the connection of the power supply to the plug in the back.

Finally, it could be that you had a trace or two lift.