Soundigital 8K

[brandes.cm]

What is the IC located next to the IR2010's, the number is scratched off. I will post a pic in a bit.

 

[brandes.cm]

Photo

I need a resistor value also circled on the pic. Emails sent off to Jose Diaz and others, no reply yet.

 

[brandes.cm]

Anyone from Brazil that can get any info, reps in the US are non-existent.

 

[brandes.cm]

HEF4070 is the IC and the resistor is 10ohm .25watt

 

[timwebb]

i never seen one.... thought it would be kinda bigger for a 8k amp.

 

[brandes.cm]

Efficient, using a microprocessor for all the pwm signals and IC's for the drive signals. All that is left would be the supply and input circuitry.

 

[brandes.cm]

The clip light is always on when I have the outputs enabled. If I disable the outputs with the switch clip light goes out until the input signal is increased.

Anyone have thoughts on this amp?

 

[brandes.cm]

The clip light is figured out, switch was put in the wrong state.

I get very little output of this thing, I can see the carrier with the 40hz on it, but after the filter I get nothing. The inductors are not open, maybe the cap?

 

[Perry Babin]

Is the pulse width of the PWM signal on the carrier going from near 0% to near 100%?

If not, the problem is the signal driving the input of the class D circuit.

 

[brandes.cm]

Is the pulse width of the PWM signal on the carrier going from near 0% to near 100%?

If not, the problem is the signal driving the input of the class D circuit.

It doesn't seem to be, the layout of the 3 quad package op-amps has me baffled. A few have a square wave on the outputs while others have a triangle waveform and a few have the sine wave input signal.

 

[luka]

I would say, that could be input stage of clocked amp... triangle waveform + sine wave = pwm
what is the freq. of triangle waveform?

 

[brandes.cm]

I would say, that could be input stage of clocked amp... triangle waveform + sine wave = pwm
what is the freq. of triangle waveform?

I'm guessing the frequency to be 40-80khz, I don't have it in front of me and basing it on my scope settings that I remember.

 

[luka]

40-80k would still be pretty low for full range amp as this one should be if I remember right

 

[Perry Babin]

The amp requires that the input signal be equal to or greater than the amplitude of the triangle waveform to drive the amp to clipping. If the signal has an amplitude lower than that of the triangle waveform, the problem is in the preamp circuit, possible in the muting circuit (if it has one).

 

[brandes.cm]

What are the original outputs for this amp? The one I have is using IRFP90n20d. It was worked on before me without success, so I'm thinking these are not correct.

 

[brandes.cm]

Gate signals look good, just don't know why the output is not right.

Gate signals with no input signal.
5V/div

An externally hosted image should be here but it was not working when we last tested it.

50V/div

An externally hosted image should be here but it was not working when we last tested it.

 

[Perry Babin]

Those transistors are commonly used in the Brazilian amps.

What's wrong with the output?

 

[brandes.cm]

This is the signal out of the amp, with or without an input signal.

50V/div 10us/div

 

[Perry Babin]

It appears that you have a defective output filter (either the capacitor, inductor or both).

You didn't include the timebase setting so I'm assuming that it's set to 5-10us.

Are you using a differential probe setup to view this signal?

Does it appear to be trying to produce audio?

 

[brandes.cm]

10us/div

Differential measurement is being used.

Yes you can partially see a sine wave if I slow the time base down.

I will pull the cap and measure it.