Lanzar Opti 2200

[mike49504]

This amp has very very low output.

The sg3525a reads
pin1=1.24 pin9=1.11
pin2= 1.23 pin10= .04
pin3= .03 pin11=0.41
pin4=0.1 pin12= .01
pin5= 2.05 pin13=8.73
pin6= 3.87 pin14= 0.42
pin7= 2.05 pin15= 13.70
pin8= 4.96 pin16= 5.22

Fet readings are leg1 (gate) 0.42 middle= 13.86 third=0

output readings (tip36c) = leg 1=0.41 middle= 33.99 3rd= -.02
tip 35c = 0.41 middle 34.02 3rd= 0.41

wondering what might cause the very low output

 

[I Am An Idiot]

What is the voltage on pins 4 and 8 of the op-amps? Or pins 4 and 11 if they use a 4 channel amp.

 

[Perry Babin]

What's the DC voltage on leg 3 of Q48?

Place the black probe on the RCA shield ground.

 

[mike49504]

Q48 = 0.64

 

[Perry Babin]

Pull D20 and see if it's leaking. With your meter set to ohms, you should read several mega ohms in one direction and infinity (OL) with the probes reversed.

 

[mike49504]

ok d19 and 20 both read the same set meter to ohms 0.28 in both directions

 

[Perry Babin]

Out of the board or in the board?

Meter set to ohms or diode check?

 

[mike49504]

out of the board sitting on work bench set to ohm 0.28 in both directions

meter set to diode check 0.28 both directions

 

[Perry Babin]

Replace them to see if that solves your problem.

Remember, be very careful on these boards. They're very easily damaged.

 

[mike49504]

Thanks Perry that was the problem amp works great now

 

[erikv79]

I am fighting the very same problem, although, D19 and D20 are both working properly. I do get a slight increase and decrease in volume, kinda like a wave. Any suggestions?

 

[Perry Babin]

Does the voltage on the third leg of Q48 correspond to the audio output level?

Does the rail voltage go up and down with the audio level?

Place the black meter probe on one of the non-bridging speaker terminals. Place the red meter probe on the point where you need to measure the voltage.