I've got a question about a small car amp that I was wanting to use for an amp in my garage. The address to the schematic is posted below:
elektrotanya.com/pioneer_gm-600_sch.pdf/download.html
Trying to see if this thing still worked, I had my phone plugged into the audio in, hooked up a speaker, and powered up the amp.........nothing. I opened it up and started checking voltages. Everything was looking good until I got to the "Isolator Power" and "Isolator Circuit". Voltages were way off and audio ground to power supply ground was about 12V. When I went to hook up a scope to the input signal coming in, as soon as I hooked the probe ground to amp (power) ground, the thing starts working. All voltages looking good. At this time, I had my laptop (which was plugged into the wall) hooked up to the audio and the amp running off a 12v power supply (also plugged into the wall). I got the same positive results when I unhooked the probe and connected the 12v supply ground to earth ground on the wall plug. When I switched the audio supply back to my phone, I got same problem again. Audio ground is floating around 12V. I'm not 100% sure how the isolator and isolator power circuit works and how it deals with the grounds at 2 separate potentials. Do you have to have what is supplying the audio have the same ground as the amplifier to work, or do I have something weird going on? Thanks!
