Boss R2400d

[Hexhclass]

Amp is in protect, no short found

SG3525
1: 0.000
2: 5.02
3: 0.013
4: 0.196
5: 2.089
6: 3.572
7: 2.072
8: 0.292
9: 5.46
10: 0.017
11: 0.002
12: 0.000
13: 11.92
14: 0.002
15: 11.92
16: 5.01

Any suggestions?

 

[Hexhclass]

Driver board out for circuit when test was done.

 

[Perry Babin]

Do you have a D21 that connects to pin 8 of the 3525?

If not, is there any diode connected to pin 8?

How close is the diagram below to your amp?
http://www.bcae1.com/temp/classDtype2wdriverboardindexa998.pdf

 

[Hexhclass]

Schematic is very close.

Yes there is a D21 and it is connected same way in the diagram.

 

[Perry Babin]

Lifting D21 may allow the amp to power up but since it's defeating part of the protection circuit, you need to be careful.

With that diode out of the circuit, the softstart terminal of the 3525 should charge to about 5v.

 

[Hexhclass]

With the diode out of circuit it powers up, has rail and regulated voltages but protect LED still on.I install the driver board but no oscillation in the outputs

 

[Perry Babin]

Did you reinstall the outputs? Don't if you haven't.

Do you have any DC voltage across the speaker terminals?

 

[Hexhclass]

Outputs was always in circuit.Only the driver board was removed.
Everything is in circuit right now apart from the diode.I see no DC offset.

 

[Perry Babin]

The 'on' signal is missing, most likely.

Find the optocoupler that drives the on pin of the driver board. What's the voltage on that pin?

 

[Hexhclass]

I see +64v on the ON pin using both grounds

 

[Perry Babin]

There is an optocoupler that has one output terminal going to ground and the other output pin for that same optocoupler section connected to the ON pin. Shorting those two pins together will enable the output stage. It may require an audio signal to start oscillating.

On the diagram, these are pins 5 and 6 of U7. Yours may be different.

Be careful The protection circuit is still bypassed.

 

[Hexhclass]

After shorting the pins I see oscillation and it is producing good audio.

So the optocoupler is bad or something connecting to it?

 

[Perry Babin]

Post the DC voltage on all terminals of the LM393 next to the 3525.


Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:

 

[Hexhclass]

Pin 1: 0.063
Pin 2: 2.259
Pin 3: 0.204
Pin 4: 0.000
Pin 5: 0.071
Pin 6: 2.259
Pin 7: 0.071
Pin 8: 5.01

 

[Perry Babin]

Desolder the thermistor. Does that allow it to power up without protect?

 

[Hexhclass]

Still in protect

 

[Perry Babin]

Have the voltages on the 393 changed?

 

[Hexhclass]

Voltage still the same

 

[Perry Babin]

Find the optocoupler(s) that corresponds to U5 (may be a different designation). What is the DC voltage measured directly across pins 1 and 2?

Across pins 3 and 4?

 

[Hexhclass]

Found a Leakey transistor .The collect is connected to one of the optocoupler input. Replace it as and all seem well.

thanks