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Help replacing DAC chip?

bluefish

pfm Member
My Avondale CD3 stopped giving any output, so after speaking to Les, who has stopped doing close up circuit work, I've sourced a new TDA1541A chip. Only problem now is working out how to swap it. Is it going to pop out or is it a soldering job?

Here are some photos:
https://flic.kr/p/2jXaTuZ
https://flic.kr/p/2jXbJgH

(hope those links work OK)

All help gratefully received.
 
the first pic you show is a dac in a socket; if this is what you have in your ACD3, as many are, you can do this with no tools. Slip a chopstick or sim under the pcb in the middle under it so it is solid before you seat the chip (try this with the one you have first!! if no audio then try again, with your spare dac ...*)

The second pic you posted shows the dac soldered on the main PCB - is this inside your ACD3?
If so, it requires de-soldering from the underside to replace. This is not a problem for any competent DIYer - whereabouts are you? you might find someone here on pfm to assist. If you are near Bath, I would be happy to :D



*the CD3 dac is flexible by design and only supported at the far ends , deliberately.
DO try the chopstick trick, re-positioning it to suit each of /firmly re-seat all IC chips that may now be a push-fit in sockets - before worrying about the DAC.
 
Is the first pic the replacement and the second the CD3?
That's right.

It does look to me as though the current CD3 DAC chip wasn't mounted in a carrier, so will need to be unsoldered.

I'll try checking all the chips are in firmly first. And then I've had dry solder joints before that just needed a quick touch with a hot iron to re-wet.
 
If so, it requires de-soldering from the underside to replace. This is not a problem for any competent DIYer - whereabouts are you? you might find someone here on pfm to assist. If you are near Bath, I would be happy to :D
I'm in Warwick. Bath's is a bit of a trek, but thanks for the offer. Is there anyone around here who's comfortable around these chips and boards?
 
well that is marked as 1997 going by the code is it not?

there was a brief rerun in the late 90s but I was told they have not been made since I went looking for an original had to sell for a non crown version as genuine ones were going for silly money
 
First DACs don't just die that easily, so I'd have checked the analog session of the circuit
Your DAC chip is the S1 while the replacement is plain vanilla version, that means a slight decrease in sound quality. One more reason to check the rest of the circuit. I don't know what modifications Les makes but the original is OPA based so I'd check voltage to these chip as well the analog input and output.
Good luck.
 
I've never had a silent TDA1541A, they've always gone noisy or lost a bit or two. The mute circuit on the output of the CD3 needs all of the analogue supplies to be working correctly to lift, so I'd check there first. This is something you really need a scope for if the PSUs are correct. Look for data, L/R word and clock on the digital input pins, then look for any analogue signal from the output. If there's data going in and absolutely nothing coming out then I'll accept it's a dead DAC.

There are loads of R1 DACs floating about at the moment - avoid them. A donor player should yield a good working plain variant. If you're worried about the lack of Crown markings there are simple modifications that can be done to the supplies around the DAC that will yield far better returns than worrying about 1/2 of an LSB error.
 
I've never had a silent TDA1541A, they've always gone noisy or lost a bit or two. The mute circuit on the output of the CD3 needs all of the analogue supplies to be working correctly to lift, so I'd check there first. This is something you really need a scope for if the PSUs are correct. Look for data, L/R word and clock on the digital input pins, then look for any analogue signal from the output. If there's data going in and absolutely nothing coming out then I'll accept it's a dead DAC.

There are loads of R1 DACs floating about at the moment - avoid them. A donor player should yield a good working plain variant. If you're worried about the lack of Crown markings there are simple modifications that can be done to the supplies around the DAC that will yield far better returns than worrying about 1/2 of an LSB error.

MJS, interesting to read your post, which tells me this job is way beyond my level of tinkering. Any chance you might feel like taking on a rescue project?
 
Sorry, I'm not doing any of this sort of work at present for a few reasons.
 
I've never had a silent TDA1541A, they've always gone noisy or lost a bit or two. The mute circuit on the output of the CD3 needs all of the analogue supplies to be working correctly to lift, so I'd check there first. This is something you really need a scope for if the PSUs are correct. Look for data, L/R word and clock on the digital input pins, then look for any analogue signal from the output. If there's data going in and absolutely nothing coming out then I'll accept it's a dead DAC.

There are loads of R1 DACs floating about at the moment - avoid them. A donor player should yield a good working plain variant. If you're worried about the lack of Crown markings there are simple modifications that can be done to the supplies around the DAC that will yield far better returns than worrying about 1/2 of an LSB error.

Good advice.

The classic failure mode of the TDA1541 is static like noise that gets worse as the chip warms up.
 
If you're worried about the lack of Crown markings there are simple modifications that can be done to the supplies around the DAC that will yield far better returns than worrying

I am aware of many of the improvements to the supplies around TDA1541a but would be interested which mods you are referring too (sorry if this is a little off topic).

Cheers
Ian
 
I've never had a silent TDA1541A, they've always gone noisy or lost a bit or two. The mute circuit on the output of the CD3 needs all of the analogue supplies to be working correctly to lift, so I'd check there first. This is something you really need a scope for if the PSUs are correct. Look for data, L/R word and clock on the digital input pins, then look for any analogue signal from the output. If there's data going in and absolutely nothing coming out then I'll accept it's a dead DAC.

There are loads of R1 DACs floating about at the moment - avoid them. A donor player should yield a good working plain variant. If you're worried about the lack of Crown markings there are simple modifications that can be done to the supplies around the DAC that will yield far better returns than worrying about 1/2 of an LSB error.
 


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