Soundstream xxx4000d driver board

[Perry Babin]

I wouldn't be concerned about the rail voltage discharge rates. I doubt that it's an issue (I could be wrong).

All of the amps with the driver board using the TO-220 drivers and the large outputs have the same problems as you're seeing.

The high-side outputs run hotter because there isn't enough drive voltage.

Adjusting the resistor in the constant current source changes the low side drive but getting more voltage for the high-side output isn't as easy.

 

[maurosubito]

Now amp is in the chassis and seems working well.
I have to test with a charge.
Mje340-350 works fine, now with fan the temperature of low side pre-drivers is about 45-50 C.
In the high side there is only one transistor that become hot.
I change his position in the board from q130 to q134 and only this transistor is hot.
I think need to change but I haven't a replacement.
With insulator and lock it seems works.

The only problem now is that R361-R362 arrives at 80-90 celsius degrees in 5 minutes.

I have changed from 10k-3watt to 10k-5watt but temperature is very high

 

[Perry Babin]

In other amps (and likely in this one), those resistors are connected directly across the rails and are used to bleed off the charge in the rail caps. Heating is normal. That's why they use large resistors. The larger size helps them to better dissipate the heat.

 

[maurosubito]

Ok thanks Perry, amp works, I leave 5watt resistors

Thank you very much

 

[juannoguera]

Hello, i'm repairing an xxx4000d driver board.

Now amp works fine but it has a bump when start sound and the small transistors (ktc3228-kta1277) become hot in 30 seconds after power on.

Is it right or I have a problem in the amp?

I think to replace small transistors with mje340-mje350

you will have the diagram of this driver board? I need resistors r192 r190 q124 q123, all burn

 

[maurosubito]

I'm sorry but I've lost all the pics of the board when my hard disk is dead