Soundstream XXX6500

[mike49504]

I replaced the outputs in this amp. Also repaired some of the work done by someone else.


Amp powers up and relays kick on But no output.

I set my scope to 10us 20V/div I dont see a square wave on any of the outputs.

The amp is producing both + - rail and regulated voltages .

Wondering where i go from here?

 

[Perry Babin]

If you set your scope to AC coupling, 2mS and 5v/div and drive a strong signal into the amp, do you see any sort of signal on the gates of the outputs?

 

[mike49504]

Scope set to 2ms 5volts/div AC coupling. Sine wave generator set to 100 hz.

I dont see any kind of wave the trace just deflects

 

[Perry Babin]

Can you see the deflected trace or does it go off of the display?

 

[mike49504]

on 1 side i can see a deflected trace on the other side the trace doesnt do anything

 

[Perry Babin]

Is the board marked with all of the various supply voltages?

Are all of those present?

What DC do you have on the FB pin?

Do you see audio on the input pin?

 

[mike49504]

I have audio signal on the input pin for the driver board.

The FB PIN:0.46 V

The FB_G:0.46 v

+15V:11.95

+18V:12.42

-15V:-10.92

-18V:-11.92

 

[Perry Babin]

I can't read all of the silkscreen on the powerbass I have here (similar to the SS amp you're working on). Here are the voltages from the driver board. Pin 1 is the input pin. Are yours similar?

It doesn't appear that your amp is producing rail voltage.

 

[mike49504]

Heres the readings i have

1:0
2:0
3:12.9
4:12.1
5:0
6:-11.0
7:0
8:-120.0
9:-119.6
10:-118.7
11:-118.8
12:-118.6
13:0
14:-118.3

 

[Perry Babin]

9 and 14 should be 15 and 18v above pin 8. Find the regulators feeding those pins and check them.

Why are the voltages so different than the previous voltages you posted?

 

[mike49504]

I reflowed the solder on the driverboard pins that might be why the voltages are different.

I have a MJE172 That connects to pin 14

The other one next to it is a MJE182

Are thoose my regulators?

If so what pin is ground?

 

[Perry Babin]

Qa1-4 are drivers for the outputs.

Those voltages are being produced by the small transformer adjacent to the power supply driver board. Do you see a square wave on the FETs standing near the transformer?

 

[mike49504]

Well i have a problem with QA3 and QA4 there is no voltage present on all 3 legs.

 

[Perry Babin]

Check the operation of the small power supply.

 

[mike49504]

On the Irfz44's (fet30,31) I have the following voltages

Leg1:3.02
Leg2:9.06
Leg3:0

I also see a square wave on leg 1 of thoose fets.

 

[Perry Babin]

Do you have at least 12v feeding the amp?

What's the DC voltage on the cathode of DP11?

 

[mike49504]

Guess my current limiter took a dump I only had 9 volts feeding the amp.


DP11:-93.1

 

[Perry Babin]

Does the amp work without the limiter?

 

[mike49504]

Just checked that amp powers up fine without the limiter but still no output.

 

[Perry Babin]

Are pins 9 and 14 still on the negative rail?

If so, are R18 and R19 within tolerance?