Cambridge Audio Azur 540R v2.0 repair, no sound

[Chungalin]

I’m working on this one. From outside it seems a fine set, but inside is rather cheap. All Samxon 85°C grade caps. Those close to heatsinks are toasted.

I find toasted glue around DSP (Decoder) PCB heatsink (with 12V and 5V regulators). Tracks corroded by roasted glue, 12V track is burnt and open.

I clean everything, removing heatsink, large caps and even rectifier bridges (2 DB104G). Repair tracks, replace C102, C94, C93, C143, C141, C144 that are "tanned" from "heatbathing". Now there’re all voltages (12V, 5V, -12V, 2.5V), but still no sound. Damn, what a crap!

I’m getting SM from ET to keep wasting time on this.

[Chungalin]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

It was fixed. The problem was that while replacing C94 I damaged positive track and IC9 didn’t get 5V. My fault, but... those traces are really brittle!

BTW, I have a V2.0 set and SM is for v2.0 too, but I can’t see IC18 (3.3V regulator) anywhere in PCB (both sides). IC9 just gets 5V instead of 3.3V.

So, conclusion: beware of toasted glue!! You’ll find plenty of other cases in this forum of this same long-term issue.

[madan1]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

I'm now working on one of those and just got one of that WTF moments... the damn thing produces sound! No, no what you think! No speakers hooked upped to the unit, no headphones connected.. just the bare unit with a wire for FM antenna. Powered it up and it started to play music... I'm not joking!
The sound seems to be coming from somewhere around the power supply boards....
Anyone seeing/hearing something like this?

[petehall347]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

output devices singing .. heard it plenty of times .

[madan1]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

So what could be producing the sound ( not noise... sound.. the sound from the input - in this case FM radio )?
p.s. The sound level is affected by the volume control.

[petehall347]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

the output devices is where the sound is coming from .

[madan1]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

Can you be more specific?
Again - there are no speakers or load hooked up to the amp. Also, it happens when the headphones are plugged in. What components might be vibrating and why?
Might it be something in the power supply affected by the current draw from the power amps?

[madan1]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

p.s. Here is the service manual.

[petehall347]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

there are 2 large heat sinks with a fan blowing on them with the output devices fastened to it . this is where the sound is coming from .
its just the nature of the beast .

[madan1]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

Well, I see the logic here... but big "no, no".

Weird or not, it seems that the ceramic caps on the headphone pcb are singing!
Just googled for singing ceramic caps and it seems that it is not such an uncommon thing.

[hyperglobalmegadude]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

I have a similar issue with a Cambridge 540R - no sound output. Do you folks happen to have a parts list for the replacement caps?

[hyperglobalmegadude]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

...I probably need to find the failed one first and my test equipment is lacking - the display works fine so I suspect an issue in the decoder board.

[madan1]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

Here is a link to the service manual https://www.badcaps.net/forum/showpo...65&postcount=8

Start with probing the voltage rails.

[hyperglobalmegadude]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

Got it - thanks.

I poked around a bit and replaced a few caps I thought were bad..no luck there though.

Did notice though that the headphone output has a faint/crackly signal from the source (should have checked that before...)..hm

[madan1]

Re: Cambridge Audio Azur 540R v2.0 repair, no sound

Check if IC17 has proper power supply ( +7V and -7V ). Also, when you plug the headphones, do you hear relays clicking?