Xtant 3300C idle current

[AlphaC]

Hi do anyone know the idle current of this amplifier?


Thanks

 

[Perry Babin]

The idle current is going to depend on the bias setting for each channel.

Do you think there is a problem with the idle current of your amp?

Have you tried contacting xtant to see if they could help?

 

[AlphaC]

When first powered up it draws 6.5A. After approximately 30 seconds it steadily drops to around 2.3A. Add another minute and there is like an arcing sound coming from the psu fet's / diodes. I bought this as non working. It would make sound, but fades out after a minute. I could try to contact Xtant for service manual or a schematic.

 

[Perry Babin]

It will be helpful if you can determine whether the excessive current is passing through one of the audio channels.

If you power down then immediately power up again, do you have the same 6+ amps of current draw?

 

[AlphaC]

I have the same audio level in all channels until it drops out and no dc offset. I have only 13V on the rail with 14V going in. Sounds to me like the psu fet's starts to oscillate (crackling sound) the pwm controller also get very hot. Checked the fet's for shorts and didn't find any.

 

[Perry Babin]

The 3525 shouldn't be getting hot.

Do you have a scope?

 

[AlphaC]

Yeah I thought so. I have a scope.

 

[Perry Babin]

Are you getting clean square waves from both outputs of the 3525?

 

[AlphaC]

Well both puts out 360KHz thats how far I got before D3 started unsoldering itself. A schematic would be nice.

 

[Perry Babin]

360K is FAR too high. Are you sure that it isn't 36k?

 

[AlphaC]

Seems to be legit if I didn't mess it up My scope skills are limited.

 

[Perry Babin]

For most testing with a scope, you can get by with 2 timebase settings. 2ms for audio and 10us for power supply. When you set it to 10us every time, you will see about 3 cycles on the display and immediately know that the frequency is about right.

Either the timing capacitor or one of the resistors for deadtime or timing could be out of tolerance.

 

[AlphaC]

Nice tips there, thanks. I have checked the timing resistors RT - RD and timing cap CT they are all in spec. Based on those values I calculated the frequency to be around 40KHz. I could try to swap the 3525 maybe its internally shorted?

 

[Perry Babin]

The problem is most commonly with the timing components but the 3525 could be defective.