Ayuda soundstream L1.2100D

[Mjimenez]

I'm already connected yet I don't see a change in the oscilloscope

 

[Perry Babin]

Do you have audio reaching the driver board?

 

[Mjimenez]

I injected 45 Hz without the rectifiers he could not see anything before if it was seen in pad 1 of the board

 

[Perry Babin]

That sounds like a preamp level problem. You'll have to determine where the break is. It could be a dirty switch or pot.

 

[Mjimenez]

I already checked the preamp is fine but I still have 10.5v in the oscillation card I found an o74c in fault and a resistance of 470 ohms, now it oscillates well but the 10.5v continue in the gate of the output mosfets I try to turn on the amplifier with the mosfet and the current consumption increases to 18 amps and I quickly turn it off I can't find why because of so much volt now on pin 1 and 2 of the board I get 3.4v

 

[Perry Babin]

See attached.

 

[Mjimenez]

Hi Mr. Perry, how are you? tl072I believe if I have but lm6172 no ... If I notice that those two heats up is this the problem?

 

[Perry Babin]

What's the DC voltage on the supply pins of those op-amps.

What's the frequency of the square wave on those op-amps?

 

[Mjimenez]

power supply pin 8. 11v and pin 4. -10.3v is for the two operational amplifiers and the square wave was only found in the lm6172 and is 117.3khz and in the tl072c it is triangular of 117.3 khz both in pin 7

 

[Perry Babin]

I think they're running hot because they're operating at high frequency. Are they producing the 117k without the 14 pin IC in the circuit?

 

[Mjimenez]

it's inside the 14 pin ic

 

[Perry Babin]

Are you saying that the 74hc00 is in the circuit?

 

[Mjimenez]

yes it's set

 

[Mjimenez]

It already oscillated but in gate I only get 2.5v on one side on the other 1.8v I will continue checking the plate

 

[Perry Babin]

Is that amplitude measured with a meter or using a scope? You need to use a scope.

 

[Mjimenez]

In the end I managed to oscillate good, 4.8v a each side of mosfets but the coil that goes to the output makes too much noise and the current consumption increases to 18 ampers ... now I found a 10 ohms 5w resistor open and a capacitor of 10mf 100v flown, I remove them but still making that noise ... will the coil be damaged? and this is a resistor or a diode? it marks me 85kohms

 

[Perry Babin]

The part in the center image is a thermistor. You can put yout meter across it and hold your finger on it and you'll see the resistance change.

The inductors in the older amps like this had a high failure rate but I think that's been resolved. The shorts (can be seen as a change in current when it's twisted) are generally on the terminal windings or very near and repairable by insulating the bare area.

 

[Mjimenez]

I already checked the coil, it is fine still making a sound
3 capacitors and 1 resistor heats up immediately ... what should I check right away?

 

[Perry Babin]

Post a photo of the parts that are heating up.

 

[Mjimenez]

are marked with red circles