Old school Soundstream Tarantula

[caraudioguy2100]

Not sure of the model number .

I got this amp in for repair and when I try to increase the input voltage
(Turn the volume up on head unit ) the amp will protect on me and as soon as I lower the volume on head unit it will power back up .

Does this sound like a problem in the preamp section ?

Or wondering where I should start checking

 

[Perry Babin]

Does it do it without a load?

 

[caraudioguy2100]

No

 

[caraudioguy2100]

Let me check a few things and I’ll get back to you since the amp has no output now

 

[Perry Babin]

If it only does it with a load, it's generally due to an emitter resistor out of tolerance, with a bad connection or a leaky protection transistor.

When it gets audio again, drive only one channel with a load to see which channel is causing the problem.

 

[caraudioguy2100]

I found an LM34DZ which appears to be a temperature sensor

Leg 1 is the +5 volts
Leg 2 is the output
Leg 3 is the ground

According to the data sheet I found

Here are the measurements I get

Leg 1 to Leg 2: 30.0 ohms
Leg 1 to leg 3: 16.1 ohms
Leg 2 to leg 3: 16.4 ohms

Does this appear to be defective or is it suppose to measure like this ?

 

[Perry Babin]

If you heat/cool it do you get a varying output?

Those resistances do seem low.

 

[caraudioguy2100]

Heating or cooling it makes no change at all .

I will go through the rest of the amp and see if I find anything else bad .

After going through the amp I will order a new one and take readings off it .

I think the amp is stuck in protection now since it’s not producing rail or regulated voltages

 

[caraudioguy2100]

Ok something in the circuit is causing the temp sensor to read bad .

There are caps that show they are shorted along with multiple transistors reading shorted.

I will have to check the entire circuit to figure out which part is causing This issue