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Cambridge A3i Down

Iain

Iain

pfm Member
Power LED is on. No output at all, as if the mute circuit is engaged. Inside all fuses ok.The main board has some LED's all of which sparkle. one more dimly.

I have a feeling that there is a muting relay that is sensing (or thinks it is) DC, but I can't get a circuit diagram off the net.

It has done this in the past and eventually come back to life, but not this time. Interestingly it has never failed in use, but has been found with the volume full on after my daughter has been playing in the vicinity, although switched on it was not playing at these times as far as a I know.

Does anyone have any experience of this cheapy ,but goody? Any advise appreciated please. Or a copy of the cambridge a3i circuit diagram please


Thanks :)
 
I have had a few A3i's. While they sound wonderful, they are not the most reliable.

It sounds like the relay could be defective. This relay switches on when the unit is powered and off when the mute is activated.

My A3i is having a relay problem at present.

The designer (Alex Nikitin) sometimes posts on DIY Audio (user name x-pro) and has posted the schematic of the power supply board one or two times.

If all the led's light I would say there is very little wrong.

What could have happened is the amp when played with the volume right round could have activated the protection circuit and burned the relay contact.

It could be that, or the protection circuit is activated all the time, hence no sound.
 
Thanks. What are you going to do about yours? Is it easy to identify the relay on the board?
 
The relay block is at the back of the power amp board. The relay is housed in a small black plastic box with 'Cambridge Audio' written on it.

When I get round to it I will take out the power amp board and try and find a replacement relay and replace it.

My problem is not as severe as yours. I just loose the right speaker every so often. Muting the amp a few times gets the relay working again and right channel comes back.

if you can live with the problems, the A3i is a truly fine integrated.
 
It have just realised that my Creek 5350SE went through a pair of relays. Similar problems to the A3i (loss of channel etc..)

Later Creek amps (the A3i was a Creek designed product) all have relays near the output and it seems to be a problem. The lower powered Creek amps (4330 for example) do not seem to suffer poor conact problems. However the higher current designs (i.e. 5350SE, and my A3i) are more suspect to relay problems.

This is in my experience. I have owned three A3i's, one 4330 and one 5350SE. The 5350SE and 2 A3i's have had relay problems.

When I cange the relay in my A3i I will buy the best quality I can get hold of.
 
Cheers BradNad.
I have a slipped disc at the moment. So trying to use my vertical time well (Info gathering). When I recover I will have another look inside and post my findings. If you get there first can you let me know the part number you come up with for a replacement relay

Cheers

Iain
 
Iain, I contacted Richersounds service department and managed to get a relay. When it arrives, I will keep you informed.

The guy there was very helpful and knew a lot about the A3i.

He says the most common problem was thermal runaway caused through faulty transistors (not the main output transistors) but the small grey/silver ones (there are 2 of them). He is sending some of these as well. I wonder if this is your problem?

Also the LED's were soldered to close to the PCB on early A3i's which caused problems.

What I did not know was the A3i runs in pure class A! So yes, it is a 50W class A integrated. I was always led to believe that it was class A/B heavily biased to class A, but I was wrong.

It really is a superb integrated, that few know about.

Will keep you posted.
 
Cheers.

I hope you kept his name! If I end up on this path I may change a few other bits in there too!

I agree it is a good amp, but 50w class A? Maybe that is where all the heat related probs come from.

Keep me posted

Cheers

Iain
 
Hi BradNad

Did those relays arrive? I am hoping to be well enough to fix my amp in the new year, so interested in your findings.

I noticed on another posting that you appear to have a wider experience of Integrateds around this price point, than I do.
I have got hold of a Rotel 931 and a Cambridge A300 and have to decide which of the 3 to keep, without being able to compare the broken one.

Have you or anyone else got an opinion? Wished I had started another thread now!

Cheers
 
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