That Tl49c if apply pressure to the corner of that chip the buzzing noise goes away on the inductors and the DC voltage on the speaker output start to go away
Ok replace tl494c pwm controller. inductors are not buzzing anymore but still not getting the two LEDs by the RCA inputs to light up and still have 24 volt DC output on the speaker terminal. Got my oscilloscope in now. ready for some real testing
This is only 7 terminals and I don't know which IC is which but these are far different from the other set before changing the ICs.
Looking at the positive speaker terminal, what is the DC voltage on that terminal before and after LED 400 switches on?
Looking at the positive speaker terminal, what is the DC voltage on that terminal before and after LED 400 switches on?
Before amp turn on it's showed 18 volts and decreases with the remote wire not connected. Once amp turns on it goes to 23 volts DC.
Do you have a 120v incandescent bulb (not LED or fluorescent) that you could connect across the speaker terminals? A dummy load would work but may draw excessive current, you'd have to be ready to quickly remove power/remote.
Connect whichever you have to the output terminals. When you power it up, doesn't it draw more current with the load than powering up without a load?
Check before and after LED400 lights up.
Check before and after LED400 lights up.
Yes. with dummy load it pulled 23 amps powering on. without dummy load it only pulled 3.8 amps. Before LED 400 turns on there's no difference before or after with the amp drawn
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That should have disconnected all drive from the opto-couplers. You can confirm by measuring the DC voltage between the diode pins of the couplers. They should remain at 0v when the amp is on.
One of the opto-couplers may be leaking. You need to remove them AND install a jumper between pin 5 and 6/7 on each one. Don't apply power without the jumper. Do you still have significant DC?
One of the opto-couplers may be leaking. You need to remove them AND install a jumper between pin 5 and 6/7 on each one. Don't apply power without the jumper. Do you still have significant DC?
All opto-couplers show on pin 2&3 .243 volts but it fluctuates between .243 and 0 volts. I set my oscilloscope to diode function.3 of the 4 opto-couplers on pin 2 and 3 show 0L. One of the opto-couplers shows 0.005. I will be pulling the opto-couplers out that show 0L out now and jump pins 5 and 6/7
I removed all four opto-couplers and jump 5 and 6/7 together still have dc 23 volts at the speaker terminal.
That would make it seem that you either have a leaky output.
All outputs should be at 0v (gate to source). Is that what you have on all outputs?
All outputs should be at 0v (gate to source). Is that what you have on all outputs?