Shure PG88 Receiver killed by Phantom Power??

[memoguy]

Today I connected a Shure PG88 Dual Channel Diversity Receiver to a foreign sound system, but was not able to get any single out of the receiver. The receiver was clearly on, as the display was showing the radio Chanel, however even when the beltpack mic was on the correct channel, the receiver would not show any signal (the AF light was off, the ready light was off). I then took the system back to my usual sound system, and it still did not work, however using an identical receiver the mics were picked up just fine. This receiver worked yesterday, and now after connecting to this different system does not work.

I then found out that the foreign system which I connected to is setup to supply phantom power on all input all the time, and that this function cannot be disabled. So this makes me think that the phantom power killed the PG88. However, I have always thought that all audio gear is built to be idiot proof, rejecting phantom power if it is not needed. In fact I had a trainer tell me that phantom could do no harm to any gear, so if in doubt I should just turn it on.

I called Jands, the Australian distributor for Shure, and they said that the PG88 would be find if it had phantom power on the input. However we then walked though all the troubleshooting steps on the phone (reconfiguring system, using a different power supply) and it did not resolve the problem. He said that if the PG88 is still under warranty then the failure will be covered.

I am not sure that we still have warranty (I think it has expired), do you think the phantom power could have caused this issue?

 

[FMEng]

It is very unlikely that phantom killed your receiver. Theoretically, if it had, it would have killed the audio output stage, but the indicator lights would still work. The indicator lights are showing that something else is wrong with the unit.

There are instances where phantom power damages other equipment, but wireless receivers are designed to accept it without damage because it is so common on mic connections.

 

[memoguy]

Ok, I see. I wonder what killed the unit then. Because it worked, then I plugged it into this other system with 48 volts, and now it no longer works.

 

[FMEng]

Ok, I see. I wonder what killed the unit then. Because it worked, then I plugged it into this other system with 48 volts, and now it no longer works.

Impossible to tell why it died. It could have been a component ready to fail, and turning the unit off and back on or thermal cycling gave the final push.

 

[Chris15]

I have actually heard of phantom causing Shure receivers to get grumpy.
I can't remember the details clearly, but I think it was more a case of better with it off rather than smoke release category...

 

[museav]

I agree with FMEng, even if it the phantom was questionable is might take out an output cap but very unlikely to affect the front end of the receiver so it could be just coincidence that this occurred when they had phantom power turned on.

Sort of grasping at straws but any chance that receiver is a different Group (H7, K7, M7, etc.) than the transmitters you tried using with it? Were all transmitters powered off when you plugged in the receiver?

 

[David Ashton]

phantom power is most unlikely to cause the problem, but phantom power and a miswired lead is a possibility worth checking, pin 1 crossed with 2 or 3, or shorted to 1 or 2.

 

[memoguy]

any chance that receiver is a different Group (H7, K7, M7, etc.)

DAMN! You were right. Why we have three receiver/transmitter pairs, two of which have the same group and one that is of a different group baffles me They were all bought at the exact same time...