I have one of these at the moment and it has a fault that is built into the operation.
What it does is it does'nt give a signal to my d/a convertor unless it is playing music, it drives me nuts as the d/a convertor is searching madly for a lock, relays going beserk, until the transport is playing. and this starts up again after the disc ends.
Can anyone tell me what mod to do to make it give a signal when it is turned on like normal transports do. I have included a diagram of the decoder it uses, it seems that it has an intergrated dac in the decoder, but Audio Research do'nt use it, as it is a transport only.
Thanks for any help
Cheers George
What it does is it does'nt give a signal to my d/a convertor unless it is playing music, it drives me nuts as the d/a convertor is searching madly for a lock, relays going beserk, until the transport is playing. and this starts up again after the disc ends.
Can anyone tell me what mod to do to make it give a signal when it is turned on like normal transports do. I have included a diagram of the decoder it uses, it seems that it has an intergrated dac in the decoder, but Audio Research do'nt use it, as it is a transport only.
Thanks for any help
Cheers George
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If it is an aspect of the design as opposed to a fault, getting around it might prove difficult given that mute on the SAA7341 is a uc controlled function. You may be able to connect the kill signal to standby but you would need the datasheet for that. It might be easier to trigger mute in the dac using the out of lock signal from the input receiver.
Thanks for the reply rfbrw, I was beging to think this one had everyone stumped. I have the full data sheet on this SAA7341 if you want I could email it to you, I have found on it some of the info you talked about I'll post one in this reply and the other one in another, Hope you can give me some simple steps to fix this problem from this data sheet, as I have zero knowledge in digital, but I can instal ckock modules and such.
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The problem is only mute-like signal you have access to is the Standby signal which effectively shuts everything down including DOBM, which isn't too helpful. The mute signal which puts digital silence on the DOBM output is micro controlled and that makes it much easier to tackle this at the dac end. It is an odd problem though as most dacs have some means of addressing this problem.
BTW what input receiver is in the dac?
BTW what input receiver is in the dac?
rfbrw said:
It's the CS8420 in a Musical Fidelity A3/24
Just post another portion of the data sheet above, does this help?
Cheers George
georgehifi said:
I can see no easy way of getting access to the datastream so that one can generate digital silence when there is no audio data.
Do you know how the muting relay in the dac is triggered? Is it off RERR on the CS8420.
rfbrw, you probally cannot see from the posted diagrams, but RMCK and RERR it says on my diagram are not connected.
Cheers George
Cheers George
From what I can see of the diagram there is no attempt to mute the dac on loss of signal lock. If you have a meter, monitor the level of the RERR pin when there is no signal. If you have no meter a 470R resistor in series with a LED to ground will do. It may be possible to trigger the relays or mute the dac using RERR .
Thanks rfbrw, but I've decided not to keep this transport as it is the only one of many that has caused this problem. It 's not worth moding the dac to make it compatible, as the CS8420 is SMD and my poor old eyes could make a mistake and trash it.
Thanks for all your help.
Cheers George
Thanks for all your help.
Cheers George
Never had the misfortune of working on one of these. I have run across transports that kill the SPDIF output when the laser isn't burning. A real PITA in some applications. Whether it is done in the decoder chip, or they kill it externally, I have no clue.
Jocko
Jocko
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