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Hearing Loop PDA500/2


Cinema-John

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This equipment was working fine and then stopped after showing the Greatest Showman. Could I have over loaded it somehow?

I can still get a flash from the LED level indicators when I tap the Mic.

During playback there is nothing. The Loop test receiver is not picking anything up either.

Can anyone help please.

PS the unit is only 11 mths old.

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There are a few possibilities...

 

No signal reaching the unit (although it seems that the bar-graph is moving - so may be that's OK)

 

The loop amp itself has failed

 

The loop cable is disconnected / broken

 

I have encountered a situation with those units that if driven hard, they go into a silent 'protect' mode. Try slowly raising the level from nothing to make sure that's not happened.

Also, measure the loop continuity/resistance.

 

It's not unknown for loop amps to pack up - after all it's just another version of an audio amp - but trying out the above should help rule out external problems...

Edited by Simon Lewis
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Likely the loop has failed if there was damage to it, OR the amp has failed.

 

Disconnect the amp from the loop and measure the loop resistance, should be low probably sub 10 ohms. If the loop and all it's connections then get (send) the amp for service after a cursory look for blown fuses on the rear of the amp in the loop circuit.

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Likely the loop has failed if there was damage to it, OR the amp has failed.

 

Disconnect the amp from the loop and measure the loop resistance, should be low probably sub 10 ohms. If the loop and all it's connections then get (send) the amp for service after a cursory look for blown fuses on the rear of the amp in the loop circuit.

 

Whilst you have the loop disconnected from the amplifier, also check for continuity between the loop end and mains earth (there shouldn't be any). At least some amplifiers sense current coming back through the "-" loop terminal, but miss it returned via the mains plug earth, which can lead to them over-driving themselves if the loop is shorted to anything earthed in the building.

 

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