B2 MA 6000.1

[Achim1409]

Emitter is supplied by a 5V Zener,
collector to pin 6
Base and collector are bridged with a 100K resistor, and goes over another resistor to a diode to each driver.
Behind the diode i have 6V, after the diode 2V.
Somehow the 2V musst be suppressed. I will remove the diode to the driver, to check if there is something leaking.

 

[Perry Babin]

The base is 3v lower than the emitter. That generally indicates that the transistor is defective.

 

[Achim1409]

If i open pin 6 again, i have 5V at the Base.
Pin6 on the maiboard goes to two resistors in series, with a ceramic cap paralleled.
Than it goes to a J111 Drain..

How does it works? Should it pulled down from the mainboard? It seems, that on the drive board everything is ok.

 

[Achim1409]

Here is a picture from that circuit

 

[Achim1409]

I found in my store a new FR transistor, and exchanged. No i have 0V at the collector, and 5V at Base and emitter.
If i heat up, it seems to stay ok with closed pin 6..

 

[Achim1409]

Problem still there, but i think, i found it. if i heat up a diode in this circuit, going to a drive ic, the amp goes in protect. Marked with "A". I will see, if i can find something similar.

 

[Perry Babin]

1SS355TE or bav19ws possibly?

 

[Achim1409]

Its a 1ss355te, i look for a replacement from other drive boards i can use.

 

[Achim1409]

I have only T4 1N4148W with 4ns speed, the original has 1,2ns


could i use it, or is it too slow?

 

[Achim1409]

i used T4 for testing. Wasnt the reason for switch off. Only two caps beside this diode..i will remove them .

 

[Achim1409]

Removed this cap, with 10uf,and used two with 4.7uf 35v.now the problem is gone. I hope the voltage will be OK. I measured 12v across.

 

[Perry Babin]

The replacement diode is likely good enough but if you still have the original, reinstall it.

 

[Achim1409]

I replaced the old diode back. Heating up the area and testing was good. No Protect anymore.
For the people reading this:
I called B2, they normally mount a fan in front of the drive board to get rid of this problem. Drivers are 2092s.
The 10uf Cap makes the problem. If heat up, it starts leaking.