Phoenix Gold Phorum

Hello. I'm obviously a new member to the forum, but I've been a PG fan for many years (my ex actually worked there as graphic designer in the late 90's and helped create the PG logo). Living in Portland, I see older PG stuff for a pretty reasonable price. I picked up a 1999 era Ti 500.4 that was having a loss of sound issue in one of the channels. After some reading, it seemed like a fixable problem and I hooked it up on my bench. But as soon as I power it on the red overload light comes on and that's it. No other lights, just the overload (D51). Any ideas where I should start? I already know I should replace the caps, but they all appear to be in functional condition and there's no visibly bad spots on the board.

Thanks in advance for your help.
Aaron

Welcome to the phorum. I live in Tigard myself. Caps should be ok in a ti500.4, its the zx475ti that has bad caps. It's probably a bad fet or resistor. There are a bunch of better repair guys than me on the phorum though. Good luck with your repair. I've got the same one I'm repairing myself.

Weaklink wrote:Welcome to the phorum. I live in Tigard myself. Caps should be ok in a ti500.4, its the zx475ti that has bad caps. It's probably a bad fet or resistor. There are a bunch of better repair guys than me on the phorum though. Good luck with your repair. I've got the same one I'm repairing myself.

Does anyone have a sheet that lists what the FETs should be? I'm more familiar with repairing plasmas and you can find the factory service manuals available online.

What's wrong with the one you've got Weaklink?

One channel is stuck at full gain. I should have it fixed by now but I've been busy playing with my truck.

The red overload LED always turns on first then 3 seconds later it turns off and the fan cuts on as well as the tri-blue LED's on top. So if its stuck in overload then it has some issues, perhaps a shorted channel (this will prevent the amplifier for powering up as it will see the high dc offset.).

When you say FETs, do you mean the semi's used in the power supply? It uses 8 STP55N06 for the power supply and 2sa1943\2sc5200 for the final outputs. Not to mention the amplifier has a few fuse resistors (those may open and show no sign of damage), so check all of them they are greenish pale and grayish pale coating (not shiny like the rest of the resistors).

OK I need to change the title of the thread. The red overload light does shut off, but within 15 seconds the breaker on my converter pops. The 3 led's on top never light up, and the fan doesn't come on. I took a pic of the inner red led's that do light up if that'll help.

The two inner channels are out, each channel has two red LEDs so in the two outter channels are working and the two in the middle are out. Check out the outputs as they may have been shorted.

trickyricky wrote:The two inner channels are out, each channel has two red LEDs so in the two outter channels are working and the two in the middle are out. Check out the outputs as they may have been shorted.

Sorry I'm not familiar with the terminology. When you refer to outputs, what exactly are you talking about?

pk7tanner wrote:

trickyricky wrote:The two inner channels are out, each channel has two red LEDs so in the two outter channels are working and the two in the middle are out. Check out the outputs as they may have been shorted.

Sorry I'm not familiar with the terminology. When you refer to outputs, what exactly are you talking about?

Output would means channel, so when I stated two outputs where out that means two channels are not going to work.

I would suggest removing the fan assembly. Under it is the power supply, but you'd also have to remove the heat sinks. Be careful to take lots of pictures and note where everything goes so you can get it back to how it was. You might see something obvious under there, like burned up resistors. I bought a 600ti that wasn't obvious until I removed the heat sinks and I knew what needed to be repaired.

Btw that appears to be an older board (maybe a zx475ti leftover), the caps might need to be replaced. Notice the "zeropoint" on the board.