Hi Alan,
Guy comes highly recommended, 35+ years in the business, long work history with big hitters.
So ok on that front.

Latest from him:
”Unsure whether Protection Circuit or Power Supply. There are two Zener Diodes faulty [ short-circuit ] but need schematic to identify circuit. Hopefully not a serious problem.”

Contacted Densen for Service Manual or Schematic with following reply:
“Hi Gary,
I’m afraid a schematic no longer exist on this model – so I cannot help in that regard.

My service technicians might have a couple ideas – I put them on as CC.

When repairing them, we rely on the engineers who designed it who fortunately got it all in their head. If my technicians cannot help we can forward the unit on to an engineer, however this is a rather expensive option at 3000 DKK – however, they can always work some magic.

Marvellous....

Quote Originally Posted by Firebottle View Post
Not necessary an easy fix unfortunately, sorry to say Gaz.

If the output relays aren't 'engaging' it could be that the protection circuit is detecting a fault and keeping the relays open.
Possible faults are blown output transistors or faulty psu on one rail.

I hope your 'tech' is sufficiently experienced to work it out, it can be a challenge without a circuit diagram but many amps have similar topography.

Hope it works out OK.