Cambridge Audio Dacmagic mk2 faulty, HELP!!

[Puggie]

I have a faulty Cambridge audio Dacmagic Mk2. when you power it up the power, SCMS and 44.1k LEDs light up, I get no output (not even output relays click on) and it won;t clock to any input.

any ideas what is wrong or where to start looking, I've searched and the usual faults are the initial balanced line driver chip for the electrical inputs blown, that is fine, I get a very healthy sized signal out of it. The only service manual info I can find only covers the analogue side of the DAC (from the D/A chip onwards) I feel the problem is more likely to be in the switching circuitry in the digital domain.

please help

[rfbrw]

Do you have a signal at both inputs of the SPDIF receiver ?

[Puggie]

yes, both SPDIf inputs get a signal at the chip and both outputs working. What else should I look for? I'm going to have another go tonight and check the following:

Voltages from all the transformers

if the SPIDIf in puts are relayed to the SPIDIF output correctly and switch properly.

what else should I look for?

[Puffin]

Try putting a post on one of the threads that John Westlake the designer of the Dac posts on. From memory they are something like " Da Capo issue (JohnW) " or "John Westlake products info"

[rfbrw]

Originally posted by Puggie
yes, both SPDIf inputs get a signal at the chip and both outputs working. What else should I look for? I'm going to have another go tonight and check the following:

Voltages from all the transformers

if the SPIDIf in puts are relayed to the SPIDIF output correctly and switch properly.

what else should I look for?

Are the clock and data signals present at the dacs inputs ? Does the schematic you have show the conditions that trigger the muting ?

You might also check for excessive DC at the outputs of the AD712's.

[Puggie]

I shall have another look at the board tonight and see what I can find. IIRC there are test points for clock and data signals on the board.

Thanks everyone for the advice.

[Puggie]

I'm not measuring any signal at all at the DAC inputs

so it could be the digital IO chip (TDA1315) or the buffer chips before that.

I guess check the digital input to the TDA1315 next???

[rfbrw]

Check the voltage supply to the TDA1315 and then the clock and data outputs. Given that the clock is derived from the SPDIF datastream, it is likely that the TDA1315 at fault in the event of a failure to lock.

[Puggie]

Voltage to the TDA 1315 seems ok, analogue and digital, digital data is going in too. I'll check clock and data outs next.

[Puggie]

I can't seem to get anything out of the clock and data outs.