Repair Help need for Sinulive SLA-1500

[Funkbase]

Hi repairfriends,

income a Sinuslive SLA-1500 for repair.
What the Problem: Many Transistors of pa and of the dc-converter explodet or burned.
i have changed all mosfets and burned resistors i found. also an smd transitor found was dead and changed.
I have unsolderd the Diodes to look the function of DC-Converter. 8V up the powersupply of my bench goes to short circuit. Which Points i can search for faults?
Any ideas? The schematic is on my bench.

Thanks….

Heiko Hinke aka Funkbase

 

[Perry Babin]

Does the supply do anything, as far as oscillating, before the 12v supply goes into overload?

Did you check the drive signals before installing the FETs?

If you don't already have a diagram:
http://www.bcae1.com/temp/SLA1500.pdf

 

[Funkbase]

Yes this diagram i use.
I have no checked the drive Signals to the mosfets in the dc-converter.
The 12V supply goes now in overload. Which current i must expected in standby?
So i can use the currentprotection of my benchsupply!

Thanks

 

[Perry Babin]

A current limiting resistor is more predictable and often works much better than the ones built into a supply. Do you have something like a 2 ohm, 50-100w resistor that you use for a dummy load?

 

[Funkbase]

As dummyload i have 2*3,9 Ohm 150Watt Resistor and a bunch of high-watt resistors in series or parallel from 2 ohm to 16 ohm on a heatsink!
ok i test the dc-converter with resistor in series of 10 Ohm!
Thanks…

Heiko

 

[Perry Babin]

10 ohms is likely too high. Try 2 ohms.

If it does anything, check the waveforms on the gate pads. The FETs will likely get hot quickly so have the test set up before applying power.

 

[Funkbase]

With currentlimiting 5,6Ohm in + the blue-led is blinking and in the section of the coil it Comes a click-noise in time of a second.
in the Moment of clicking the red led of protect going down and comes up now.

Heiko

 

[Funkbase]

The waveform on the gates with mosfets in the board is only a spike just in the moment then ist clicks in the Coils.

 

[Perry Babin]

I think you'll have to remove either the NPN driver transistors (lift 2 legs is good enough) or remove the FETs to check the drive signal.

 

[Funkbase]

ok,i will remove all Mosfets and try a Startup without.
i report tomorrow the result.

 

[Funkbase]

Now i have unsolderd the mosfet in the dc-converter. The amplifier comes up without overcurrent protection. The blue led lid .
the Picture show the gate drive. One side Show a lower drive. One Transistor of the Driver was burned and i Change it to BC807/817.
Whats the next?

An externally hosted image should be here but it was not working when we last tested it.

 

[Funkbase]

Pictures

This Pictures from the Gate-Resistors.

 

[Funkbase]

i changed Q27/28. One of them was burned. The Signal was a Little lower as the original Transistors.
TNX.

 

[Perry Babin]

Do you now have good drive signals?

 

[Funkbase]

The Pictures from Oszi now. This is the drive-signal. Is this ok now?

 

[Funkbase]

What is a good drive Signal?

 

[Perry Babin]

Post the drive signal taken at the gate of the PS FETs (one from each bank if they're not the same).