Arcam Alpha 10 stuck in protection mode?

Hi everyone,

I have an Arcam Alpha 10 amp that on power up, displays a solid amber LED for around 20-30seconds then drops to the flashing red LED.

I've checked the main rails and the 5v/15v power supplies and they seem to up ok (I can measure them for a few seconds on power up), there are also no signs of DC voltage on the output of the amplifiers. I've also been round and checked all the fusible resistors but these are all ok....

I wondered if anyone had any experience of these and had any advice as to where else I can start looking?

TIA
 

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Hi,

I've attached a manual I found on the web for the convenience of anyone wishing to offer advice.

The fact that you don't find any DC present at the amp output is encouraging. I would investigate the circuits that sense malfunction for clues to what triggers protection. Because the auto bias circuit is so unusual, my suspicion gravitates there.

The DC servo design seems ok, but I'm so unnerved by the description of the auto bias current servo that I'm reluctant to offer any input. I'll follow with interest advice from other members.

My very radical instinct is to disable that network, but I'm NOT suggesting that until it's a last resort.

Good luck!
 

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