Fibonacci
New member
So I have been having a problem with the sound board on my TMNT pin and narrowed it down to the preamps (long story). I replaced them and got no change...
I checked all the voltages at the test points on the power supply board, everything looks good. Seemed like a good idea right, nice and convenient. So I got thinking about mayeb the preamps were getting bad voltage. Chek the voltage at one of them, and the -5VDC line has .26VDC on it.
That's not good...
Check the 7905, its input seems to be floating. Check the voltage at the connector, also floating.
Go to the connector on the power supply board, and the wire for the -12VDC line it completely missing... WTF?
Get looking at it, and someone had pulled it out of the IDC and just tucked it back into the bundled harness. Soldered it back into the connector, suddenly I had voltage at the sound baord. Hook everything back up, and it works! Woot!
Lesson: Check your voltages at the point where they are needed, not where they are generated. This will save you time, money and frustration.
I checked all the voltages at the test points on the power supply board, everything looks good. Seemed like a good idea right, nice and convenient. So I got thinking about mayeb the preamps were getting bad voltage. Chek the voltage at one of them, and the -5VDC line has .26VDC on it.
That's not good...
Check the 7905, its input seems to be floating. Check the voltage at the connector, also floating.
Go to the connector on the power supply board, and the wire for the -12VDC line it completely missing... WTF?
Get looking at it, and someone had pulled it out of the IDC and just tucked it back into the bundled harness. Soldered it back into the connector, suddenly I had voltage at the sound baord. Hook everything back up, and it works! Woot!
Lesson: Check your voltages at the point where they are needed, not where they are generated. This will save you time, money and frustration.
