I bought a used Radio Tech am/fm radio from a member on another forum. Before I installed it, I wanted to bench test it first. The first thing I do is check the in line fuse for the hot wire on the radio wire harness. It's blown. So, I go get a bunch(just in case) of replacement fuses and lo and behold I pop two more.

I'm attaching the black wire to negative terminal. The red wire and the orange/white wire to positive terminal. As soon as I connect the red and orange/white wire to the battery the fuse pops.

I don't think I'm doing anything wrong and what has me worried is the fuse was blown when I received the radio.

Am I not connecting the radio correctly? I know the orange/white is supposed to go to a switch wire, but for testing purposes I think I can go directly to the battery, right?


I have verified that there is no short in the three wires from the battery connections through the deutsch plug connection in the radio wiring harness.

 

I completely disassemble the entire unit isolating each component board. I then hooked each board and associated parts. in sequence starting at the radio wire harness. There were three primary boards and some misc compenents(ie. LCD display, push botton interface, relays). I just hooked each one in turn to the wire harness and using the multimeter checking for shorts, nothing obvious. I then disconnected everything again, hooked up the wire harness to a battery then reassembled each component in turn to see which one was going to pop the fuse, nothing?

Radio appears to work now. Didn't change the red,oragne/white, black battery connections. There might have been a poor connection on the circuit boards and I accidentally fixed it as I disassembled and reassembled the parts.