Phoenix Gold Phorum

Well, you guy wanted me to post up some repair threads, but not long after I posted that I started mostly only getting zed amps in for some reason, and since I don't find them interesting, inspired, or even ask that decent sounding.

I had one client who asked me to do some custom work to a pair of ti600.2s.i had done some work for him about two years ago, a pair of ti500.4s, one with a rewound transformer that bumped it's power output up so it would make its 4R power into 8R, upgraded power supply transistors and op-amps upgraded to burr brown plus a handful of other mods.

Anyhow, a bit over a year ago I designed some new input boards for 2 and 4 channel ti amps that bypass all of the crossover and other garbage as well as adds a custom touch in that the tri-leds are now capable of showing amplifier status. The first versions I built used green/red bi-color leds that basically caused the tri leds to mimic the ZX status lights :green for power good, yellow for thermal and red for o/l.

So this pair of amps got fully cleaned, the power supplies were upgraded with modern high current fets, the power supply caps were replaced and upgraded and the rail caps were replaced and upgraded as well. New input boards were built, Burr brown op-amps installed, color changing tri-led boards were built, this time with blue/red leds and it also got new switchcraft bulkhead style rca connectors.

http://cloud.tapatalk.com/s/6021dbb371f ... 122444.mp4

very cool and creative. Thanks for sharing

Do you have to change any resistor value's when you upgrade the FET's

It all very much depends on what mosfets you choose. There isn't a super simple answer to this question. If you use the fairly popular irf3205, then you should use gate resistors of somewhere around 30R. In the case of a ti500.4 the 33R gate resistors will be fine with irf3205s. Not all PG amps have values this low, nor can the power supply pwm controller properly drive modern fets in the vast majority of the early amps. You can get away with it in some, but any of the amps with an unbuffered pwm drive will struggle or fail at the edge cases if you try to drop in a handful of modern fets. The exception are the amps with very few power supply fets, like the m50 for instance. It wasn't until the zxti series that PG started buffering the pwm drive. Prior to those you will find 100R or 300R gate resistors and very mellow easily driven mosfets.

Later,
Jason