Hi everyone ! I have a problem with a JBL PRX 515 speaker amplifier! after having replaced the damaged mosfets in the woofer section, as soon as I turn on the amplifier, it doesn't start! looking at the diagram I found on the internet I noticed that on pin 11 of U2-B I should have 4MHz and instead I have nothing! I tried to replace U1A but nothing changed ! Has anyone had the opportunity to repair these modules? do you have any advice? I am attaching the schematic of the entire amplifier
Hi , check all the mpsw42 transistors and the zener diode(D607) if working .......inject a 18vdc across c634 and limit your bench power supply to 0,5amp.your psu should be drawing around 50ma or less......now check the waveforms on U602 ...pins 9 and 10.From there check output of FAN chip and then gates of mosfets.............PLEASE NOTE IF ITS YOUR FIRST TIME DOIN A REPAIR L;IKE THIS ......PLEASE STOP........DONT DO ANYTHING !!!!!!!!!
ADVISE TO TAKE IT TO AN REPAIR TECH!!!!
ADVISE TO TAKE IT TO AN REPAIR TECH!!!!
HI ! thanks for the advice ! I made several repairs on class d amplifiers but no one used a system like this to get the square wave! I'll let you know if I have any news
Transistor check instruments typically test at 2 volts or lest. A MPSA42 can operate at up to 100 v in linear application, 300 v switching. Do check in circuit that the Vbe is 0.6 to 0.7 v when it is supposed to be on, and Vce is something between the rail voltage and 1. When doing in circuit tests use only one hand at a time, voltage over 25 from one hand to the other can stop your heart. Wear no rings or jewelry on hands wrists or neck, 1 v at high current can burn your flesh to charcoal. Wear safety glasses, parts can explode. Solder can splash. The Mains voltage areas can throw molten copper. Use a scope probe or Pamona grabber to measure voltage to avoid slips that short things together.