newbie needing help i got this amp months ago and i never really get to work on in sinse i was allways have other units to work on.Here is the deal local trade in jl 500/1 slash pcb rev-3 100006 .Before me posting here i spend good 2-3 hours inspecting the unit and i didnot foud and bad power supply or output fets.All resistors near the output are teasted and all with the tolerance.There is no burn marks or signs of previous repair ,when conected to the power supply them amp works but the audio output is very very low -10 watts max.i left it working for good 30 min and no overheating in the power or output side,no current on the speaker conectors.The audio output is clear with no distortion but very low.No ternal or low ohm lights any help is apresiated
The input voltage switch near the RCA input jacks may be in the wrong position. I'm assuming that you have the gain control fully clockwise.
input voltage sellection is set to low .week aggo i had same rev-3 jl audio for repair and i swaped the input boards but the amp keeps playing very low.The only part that i see must be changed is those large capacitors near output section 1200uf 100v-they have the bubble on the top.I ve seen plenty amps working fine with those capacitors bad.
That bubble is just the plastic blow out shield for the caps vent on the top, they just about always look bubbled, but have nothing to do with the capacitors health state.
nope when i apply power to the unit power light comes right away .I spend like 30min watching the unit working and at no point there was and termal or low ohm light.No smoking or overheating parts .Audio is clear all the time no distortion but very very low.
Ok perry i got the voltages
Pin 1: 0.00v
Pin 2: 15.1v
Pin 3: 14.6v
Pin 4: 7.5v
Pin 5: 14.5v
Pin 6: 14.5v
Pin 7: 0.7v
Pin 8: 14.4v
Pin 9: 14.4v
Pin 10: 0.00v
Pin 1: 0.00v
Pin 2: 15.1v
Pin 3: 14.6v
Pin 4: 7.5v
Pin 5: 14.5v
Pin 6: 14.5v
Pin 7: 0.7v
Pin 8: 14.4v
Pin 9: 14.4v
Pin 10: 0.00v
Can you desolder Q515? If you can lift two legs and leave it in place, it will be easier to reinstall it later.
The transistor is under the preamp board near the large white resistor near the speaker terminals.
It's going to appear that it's leaking if you check it. That's normal.
With that transistor out of the circuit, does it produce audio at a normal level?
The transistor is under the preamp board near the large white resistor near the speaker terminals.
It's going to appear that it's leaking if you check it. That's normal.
With that transistor out of the circuit, does it produce audio at a normal level?
Yep i took it off and now the amp works great.Man u really know ur amps ,what parts i have to replace
I don't have a schematic diagram so I'll have to trace the circuit back on a junk board I have here. I may not get a chance to do this until tomorrow.
What is the resistance between the two legs on the bottom of the transistor? It should be about 30 ohms.
What is the resistance between the two legs on the bottom of the transistor? It should be about 30 ohms.
Since the amp is working, measure the DC voltage directly across the speaker terminals (red on +sp term, black on -sp term). What is the DC offset?
Check that transistor to confirm that the gate (at the top of the transistor) is not shorted to the other two legs. On diode check, you should read ~0.6v one direction and open when you reverse the position of the probes.
sorry for the delay in repply i had internet conection problems.I mesured the dc offset at the speaker terminals and its steady 0.00v from min to mac gain.when tested the transistor shosw ~0.9 one direction and ~1.2 in the other
If at least two of the legs of that transistor were off of the board, it appears to be defective.
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