U301
PIN1: 1.750
PIN2: 0.001
PIN3: 0.001
PIN4: -5.95
PIN5: -0.045
PIN6: 1.750
PIN7: -4.27
PIN8: 6.09
PIN1: 1.750
PIN2: 0.001
PIN3: 0.001
PIN4: -5.95
PIN5: -0.045
PIN6: 1.750
PIN7: -4.27
PIN8: 6.09
What is the DC voltage across the speaker terminals?
Make sure that you have the black probe on the negative terminal.
Make sure that you have the black probe on the negative terminal.
Confirm that it's not in protect mode.
What is the DC voltage on pins 2 and 3 of each of the 3706 driver ICs.
What is the DC voltage on pins 2 and 3 of each of the 3706 driver ICs.
The amp does have a hard time powering up with squeeling and current draw but eventually it subsides and powers up. The protect light is not on but the voltages are as follows:
U400
PIN1: 5.46 vdc
PIN2: 5.46 vdc
U410
PIN1: -0.449 vdc
Pin2: 5.45 vdc
U400
PIN1: 5.46 vdc
PIN2: 5.46 vdc
U410
PIN1: -0.449 vdc
Pin2: 5.45 vdc
Slide R316 off of its pads. This shouldn't cause any problems but you need to be careful.
Does that change anything?
Does it allow the outputs to oscillate?
Does that change anything?
Does it allow the outputs to oscillate?
R316 is a through hole ressistor, I can remove it but just want to be sure we are on the same page.
That does make a change. The amps power supply makes all kinds of wierd buzzing squeelchy noises but does draw enough current to where I think its powering the output board properly and it puts -50 vdc on the output terminals.
Perry...... I have found a mistake I have made, I forgot or missed to solder one of the legs of the new transformer I soldered on the board. I soldered it re-installed R316 and the amp produces clean audio on the scope.
I am going to clamp it down and re-test to ensure the problem is solved.
I should have caught that something was wrong when the one 3706 IC had a different voltage reading on pin 1 of U410......BRB!!!!
I am going to clamp it down and re-test to ensure the problem is solved.
I should have caught that something was wrong when the one 3706 IC had a different voltage reading on pin 1 of U410......BRB!!!!
Do you have two low value resistor (2 ohm or 4 ohm dummy load resistors) that you can insert in the red and blue supply wires to protect the output transistors?
Do you still have the potentiometer that you used to connect to the op-amp in a previous repair (BD1500?)?
Do you still have the potentiometer that you used to connect to the op-amp in a previous repair (BD1500?)?
Problem WAS solved......I resoldered resistor and powered up the amp and produced clean audio and all was good. I removed the output board to put thermal grease down and forgot to disconnect the power.
Re-installed output board and was hooking up red/blue/white wires and when I hooked up the red wire HUGE spark and now amp wont power up does nothing but squeels really loud, so I unhooked output board to see if the problem was there but no.....still same issue.....none of the p/s fets test shorted but amp will not power up now.
I dont know what I have done here any ideas????
Re-installed output board and was hooking up red/blue/white wires and when I hooked up the red wire HUGE spark and now amp wont power up does nothing but squeels really loud, so I unhooked output board to see if the problem was there but no.....still same issue.....none of the p/s fets test shorted but amp will not power up now.
I dont know what I have done here any ideas????
Are you getting a good square wave on the output pins of the 3526?
Is the DC voltage being produced across the red and blue wires exceeding the rated voltage of the rail caps?
What's the current draw when it attempts to power up?
Is the DC voltage being produced across the red and blue wires exceeding the rated voltage of the rail caps?
What's the current draw when it attempts to power up?
Pins 13 and 16 on the 3526 have a perfect square wave as well as all the p/s fets gate legs. I dertermined this with just ground and remote hooked up.
Upon trying to power the amp it squeels loudly and draws about 20 amps then subsides to about 15 amps but I only leave power to it for a few seconds because I dont want to pop anything.
The voltage across the red and blue wires is about 84 vdc while powering the amp, I just stuck a lead from my meter into each wire and tried to power to get a reading. The rail caps are 160V caps so the answer to this question would be no.
This is very frustrating the amp was working great.....but still seemed to struggle a bit powering up. I think there is a fault some where in the power supply, but I believe the output section to be fixed.
The schematic is a little confusing to me I was trying to see what the red wire was tied in with from the power supply side but they show it in like 3 different spots on the schematic and I cant tell which is what. I saw one spot where it was tied in with some small transistors maybe blew those?
What do you think?
Upon trying to power the amp it squeels loudly and draws about 20 amps then subsides to about 15 amps but I only leave power to it for a few seconds because I dont want to pop anything.
The voltage across the red and blue wires is about 84 vdc while powering the amp, I just stuck a lead from my meter into each wire and tried to power to get a reading. The rail caps are 160V caps so the answer to this question would be no.
This is very frustrating the amp was working great.....but still seemed to struggle a bit powering up. I think there is a fault some where in the power supply, but I believe the output section to be fixed.
The schematic is a little confusing to me I was trying to see what the red wire was tied in with from the power supply side but they show it in like 3 different spots on the schematic and I cant tell which is what. I saw one spot where it was tied in with some small transistors maybe blew those?
What do you think?
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