Taramps DS 1200X4 output transistors getting hot and amplifier pulling excess current

[cush man]

How much does that type cost Mr Babin?

Okay 100 watt, 1 to 2 ohms.

 

[cush man]

So the amplifier is oscillating and I'm getting sound when I touch the RCA with my finger.

My only issue is it's pulling 2.6 amps while idling. It's not pulling excess current now.

The heatsink is a bit warm though.

 

[Perry Babin]

If you buy only one, get the 2 ohm. I don't know your distributors but if you use octopart and enter ohmite 270 series 100 watt 2 ohm, you'll find those. You can use whatever type you can get with those specs.

Voltages on those points?

 

[cush man]

I have the scope measurements for channel 1.

 

[Perry Babin]

What are the voltages on the points in the graphic. If they're low, that can make the FETs run hot.

To view drive signals with a battery powered scope, black on the source terminal and red on the gate. 5v/div and 5uS, generally.

 

[cush man]

The voltages on the IC?

I'm sorry, what's 5v/div?

 

[cush man]

This how the scope looks with 5V/div and 5us...

 

[cush man]

This is how it looks with 20V/div and 2us.. channels 1 and 2 side of the heatsink is significantly warmer than 3 and 4.

 

[cush man]

A, B and E is basically the same. 10.1 volts. D and C is 9.9 volts.

 

[cush man]

This!

 

[cush man]

And would this alternative be okay?

 

[Perry Babin]

Post #50, yes but it's too low wattage. You need a 100W in my opinion unless you're just going to use it for very short periods.

#51, in general, no. They need a large heatsink to meet their wattage ratings.

Is your scope battery powered?

 

[cush man]

But aren't those 100 watts?

Yes sir, it is battery powered.

 

[Perry Babin]

I just looked at the photo but the part number is for a 100 watt resistor. I wouldn't even consider the aluminum resistors.

Are you grounding to the source leg and probing the gate leg?

Use only one probe. Take the other one off of the scope.

 

[cush man]

So don't bother with those?

Yes grounding to source and probing the gate.

Okay, so take the measurements again?

 

[Perry Babin]

Why does your scope repeatedly say 20v/div?

The 100w ohmite is OK as long as it is a 100w. The photo is a 25w. Look at the dimensions on the datasheet I posted.

The gate signals are not going to be more than ~10v p-p if you have the scope properly connected and set.

 

[cush man]

I see, I'm going to look at it again. Maybe that's the cause of the overheating?

 

[cush man]

Okay, I'm only using 1 probe and it's the same thing. What would cause the pkpk to be almost 100 volts, maybe that's the cause of the overheating?

 

[Perry Babin]

Post a photo of the end and handle of the probe you're using.

 

[cush man]

I attached the probes ground to a banana plug that I plug into the PS negative/ source ground.