Cambridge Audio 540A V1 Fault

[Vespertinestar]

Hey guys, hopefully I can get some advice on a fault with my CA 540A V1 Amplifier.


When plugged in I get one of a few things happening:


Often: Hum from power supply, nothing else.
Often: Single flash from standby light, click from relays, VERY occasionally protection light flash. Constant power hum.


VERY VERY occasionally: Unit boots and powers on. Works as normal, sounds great. A few hours/days later when left in standby the unit will cut out again and return to the previous two faults.


When plugged in even when not functioning it draws around 5W of power.


I have uploaded a few videos to try and show what happens:


VimeUhOh
VimeUhOh


I have a multimeter so I can fault find if someone tells me where to point the probes


I've had an offer of a repair from someone who knows what they're doing but I can't afford it at the moment as I'm out of work :/


Many thanks in advance


Matt

 

[nigelwright7557]

I would check first for DC on the output.
It should be less than +/- 100mV.

 

[Vespertinestar]

Thank you for your reply. After looking up how to measure DC on the output I can confirm that each output is measuring approximately +440mV. This sounds like it is a lot higher than it should be?

 

[tiefbassuebertr]

if you are able to upload the schematic diagram from your service manual, I will give you some advices.
check also out this thread under
Wide range of unreliable Amp Models with SANKEN's SAP/STD Series - Why ?
and check out the kind of output devices, which are in use.

 

[Vespertinestar]

I wish I could find the service manual for the V1 amp. I can only locate the service manual for the V2 and I'm not sure how similar they are internally


How would one go about testing the SAP15s to see if there are any issues?

An externally hosted image should be here but it was not working when we last tested it.