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]

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.

 

[rfbrw]

When the TDA1315 in my Dacmagic 2 went south, the relays continuously stuttered. I'd go through the TDA1315 datasheet and check all the voltages and logic levels as you switch through the different inputs but there is every possibility that the TDA1315 is faulty.

 

[smaalen]

I have a similar problem with my DacMagic 2 Mk2. I think it went wrong when I accidentally fed it with a sample rate that was too high (192khz).

Connected with an optical toslink cable to a PC computer source it now still locks on to the source ('locked' LED is on) but it does not produce any sound at 44.1khz and 48khz, the sample rate indicator LEDs for 44.1 and 48 do not lit either. With my TEAC cd transport the result is the same, no sound. I also tried the coax connection (only at 48khz) but that did not work either.

When I feed it a 33khz or below signal it does produce sound but it plays too slow, like a vinyl single at 33rpm. With my MacBook Pro as the source however there is sound at 44.1khz but it has a crackle and the sample rate LED for 44.1 blinks like there is a loose contact. At 48khz there is no sound with the MacBook either.

Would it be the TDA1315 that is broken and would it be a relatively straightforward repair?