Nikko ALpha III

[EchoForge]

I would expect the emitter voltage to increase as input voltage increases

A properly functioning regulator should maintain approximately ±57 V at its output once sufficient input voltage is available, rather than simply following the input voltage.

Your latest measurements confirm that both regulated rails are reaching approximately ±80 V at full mains, instead of the specified ±57 V.

That's a serious concern, particularly since those supplies feed the amplifier's driver stages. Continuing to power the amplifier under these conditions risks causing additional damage.

At this point, I would avoid any further full-mains testing until the power supply regulation issue has been properly diagnosed and corrected.

I think we've established the most important issue to address before moving any further with the amplifier boards. I'll leave it there for now.

 

[philster]

I agree. Should I pull the outputs to avoid damage of do they need to be in place for the regulator to function properly

 

[EchoForge]

I agree. Should I pull the outputs to avoid damage of do they need to be in place for the regulator to function properly

We've now established that there's a problem with the PSU voltage regulation. Both regulated rails are following their unregulated inputs, reaching approximately ±80 V instead of the specified ±57 V.

This issue needs to be properly diagnosed and corrected before proceeding with any further troubleshooting of the amplifier stages, as continuing to power them under these conditions risks additional damage.

I think we've narrowed down the immediate problem sufficiently at this point. I'll leave the next steps to those who wish to continue the troubleshooting.