Phoenix Gold Phorum

I had a 475ti that I sold to a friend around five years ago, he has just told me the left channel seems to be blown. Symptoms left side sounds distorted switched everything from one side to the other and right channel is working fine, switched speakers, RCA's, etc. Now my friend has replaced the amp and said that if I want the 475 back I can have it. Does this sound fixable? Where should I start with diagnostics?

I would say that nearly anything is fixable, just depends on time and money... As for where to start, I would start with the output transistors. Normally they fail shorted and the amp will either blow fuses, or burn up it's power supply, but it is possible for an output transistor to fail open, and will cause extreme distortion. There are also fusible 22 ohm (if memory serves) resistors in series with the base of each output transistor, if one has blown you will get a distorted channel. The fusible resistors will blow and show no signs of burning up. You have to check them with a meter.

Aside from that, it could be a problem with the pre-driver for the bad channel. It may be more worth your time to send it in.

If you decide it isn't worth your time to fix it, let me know, and I will likely buy it from you.

Later,
Jason

PG has flat rates that are pretty reasonable. They do an awesome job of going through the amp and making sure that it's 100%. I'd send it in....

werent the crossover board prone to malfunction? I dont know if it would cause the problem you described, but I just thought I would throw it out there.

joyride wrote:werent the crossover board prone to malfunction? I dont know if it would cause the problem you described, but I just thought I would throw it out there.

Yes!

Fiddle with all of the pots on the input side of the amp. Sometimes they turn scratchy and make the amp sound blown.