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No sound output from a DAC - any simple checks I can do?

Thanks for the replies and apologies in my delay in responding. Had my first covid jab yesterday and spent most of yesterday afternoon and evening with a progressively worsening headache (plus the expected bruised arm sensation), though it has gone overnight.

Continuity on both plug and case fuse is fine. I have just had a chance to check the voltages on the TDA1541A chip, results look not so good unfortunately:
pin 15 measures -15.24V;
pin 26 measures -10.34V;
pin 28 measures +5.05V.

I have looked at the area highlighted around the slightly scorched capacitor (well spotted, by the way) and see the regulator mentioned. How do I go about measuring the voltages there? Is it simply a case of placing the negative probe to a chassis screw and touching each point that the regulator is connected to the circuit board, recording each measurement found? I can the post those results too, assuming the ones already posted taken from the TDA1541A chip dont mean that it is now confirmed non-functioning/unfixable.
 
oscillating voltage on a regulator was also accompanied by failure of the S1 in my CD3, suspected failed tant cap.

had no joy finding a genuine S1 let alone a genuine TDA1541A, unless removing from a donor player
 
Thanks for the replies and apologies in my delay in responding. Had my first covid jab yesterday and spent most of yesterday afternoon and evening with a progressively worsening headache (plus the expected bruised arm sensation), though it has gone overnight.

Continuity on both plug and case fuse is fine. I have just had a chance to check the voltages on the TDA1541A chip, results look not so good unfortunately:
pin 15 measures -15.24V;
pin 26 measures -10.34V;
pin 28 measures +5.05V.

I have looked at the area highlighted around the slightly scorched capacitor (well spotted, by the way) and see the regulator mentioned. How do I go about measuring the voltages there? Is it simply a case of placing the negative probe to a chassis screw and touching each point that the regulator is connected to the circuit board, recording each measurement found? I can the post those results too, assuming the ones already posted taken from the TDA1541A chip dont mean that it is now confirmed non-functioning/unfixable.

Bugger - same as mine - you have a dead S1 :( Any TDA1541A will do - S1s are rather expensive and lots of fakes around. I scored a stash of S1s a few years back, but am down to one now and plan to use in a Micromega DAC I have.

Two Woodside's with same fault suggests something not great with the -5v rail - I would suggest replacing the regulator and the smoothing caps for the -5v rail. I'll be doing mine before playing it again...
 
Any TDA1541A will do - S1s are rather expensive and lots of fakes around.

Indeed.

Far more important to get broken player working again than worrying about whether it has a S1 chip in it. Fit a socket of you want and then if you do ever manage to pick up a genuine S1 chip you can just slot in straight in.

It really isn't hard to pick up TDA1541 chips, there are loads out there. I just pick any up when I see them being sold at sensible prices. The main thing to avoid are any being sold on ebay from China and Hong Kong. You should be able to pick up a donor player for <£50.

Here are some of stash and I have another half a dozen residing inside players too.

P1120010 by Michael Pickwell, on Flickr

Extra points if you can spot the re-marked one.
 
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Indeed.

Far more important to get broken player working again than worrying about whether it has a S1 chip in it. Fit a socket of you want and then if you do ever manage to pick up a genuine S1 chip you can just slot in straight in.

It really isn't hard to pick up TDA1541 chips, there are loads out there. I just pick any up when I see them being sold at sensible prices. The main thing to avoid are any being sold on ebay from China and Hong Kong. You should be able to pick up a donor player for <£50.

Here are some of stash and I have another half a dozen residing inside players too.

P1120010 by Michael Pickwell, on Flickr

Extra points if you can spot the re-marked one.


Third from the top right?
97 but not Taiwan?
 
Don't know but the number that have been marked S1 or S2 is scary.
In saying that logic says the later Taiwan chips should be as good as the manufacturing process was vastly improved and quality would have been higher you would imagine.
Yet conversely some of the earlier A chips can sound very nice indeed. Think it down to how good the QC was on each production line and operator.
Also i might be wrong but the first A chips there was no S1 or S2 grading so potential for early chips to be that grade as well?
Of course not everything connected to this chips that you read is true lol
 
Thanks for the replies and all the advice/assistance. Shame it isn't easily fixable (at least easy by my standards :)) but at least I now know mostly what the problem is. I'll stick it in a cupboard until I decide what to do with it.

Thanks again.
 
Having had a bit of a think about it, I may still have an original Arcam Alpha CD player in the shed which could be a potential donor for the DAC. I bought it as fully working on ebay ages ago but when it arrived it had sustained damage in transit with the fascia part snapped away and no longer able to play, the seller refunded after receiving photos and it has sat there ever since. I guess the transit damage may not have affected the TDA1541A inside....
 
Having had a bit of a think about it, I may still have an original Arcam Alpha CD player in the shed which could be a potential donor for the DAC. I bought it as fully working on ebay ages ago but when it arrived it had sustained damage in transit with the fascia part snapped away and no longer able to play, the seller refunded after receiving photos and it has sat there ever since. I guess the transit damage may not have affected the TDA1541A inside....

Perfect
 
Thanks for the replies and all the advice/assistance. Shame it isn't easily fixable (at least easy by my standards :)) but at least I now know mostly what the problem is. I'll stick it in a cupboard until I decide what to do with it.

Thanks again.

Don't stick it in a cupboard! Get it fixed - the Arcam you have will be a fine donor. And if you decide not to, still better than sticking in a cupboard is to sell it to Mike or I, we'd both repair and bring it back to like - it's a very well implemented design...except, perhaps, for the -5v regulator circuit :) I've never heard of this rail going open circuit inside the 1541 before, and now that's 2 Woodside's - maybe coincidence, but as said, I'll be rebuilding that regulator cct on mine before listening to it again.
 
One of the things I hate about being a hoarder is it seems to pay off just regularly enough to keep believing that hoarding stuff is a good thing. Anyway, I do still have the Arcam player even if I can't presently get to it due to the stupid amount of other stuff I've hoarded in the shed.

A few questions again, now.

I like the idea of fitting a socket for installing a replacement TDA1541A, it seems to reduce by at least once the chance for me to mess up the TDA1541A in the soldering/de-soldering process, as well as giving the option of putting an S1 in if I ever come across one. Is the socket I need just one of the numerous 28 pin IC sockets I see on ebay, is there a special width needed? The regulator with the heatsink fitted is marked LM340T5 with 7805 below. Am I correct in assuming any regulator sharing this number will be okay to use, and is it just the two tantalum capacitors - the little brown bead shaped ones nearest the regulator with heatsink fitted near the top of the board - that need replacing along with the regulator? I think the value mark says 4.7 and 35+ on them but their position on the board makes it hard to see without removing them, does that sound right?
 
One of the things I hate about being a hoarder is it seems to pay off just regularly enough to keep believing that hoarding stuff is a good thing. Anyway, I do still have the Arcam player even if I can't presently get to it due to the stupid amount of other stuff I've hoarded in the shed.

A few questions again, now.

I like the idea of fitting a socket for installing a replacement TDA1541A, it seems to reduce by at least once the chance for me to mess up the TDA1541A in the soldering/de-soldering process, as well as giving the option of putting an S1 in if I ever come across one. Is the socket I need just one of the numerous 28 pin IC sockets I see on ebay, is there a special width needed? The regulator with the heatsink fitted is marked LM340T5 with 7805 below. Am I correct in assuming any regulator sharing this number will be okay to use, and is it just the two tantalum capacitors - the little brown bead shaped ones nearest the regulator with heatsink fitted near the top of the board - that need replacing along with the regulator? I think the value mark says 4.7 and 35+ on them but their position on the board makes it hard to see without removing them, does that sound right?

For the socket, yes, any DIP28 IC Socket.

On the regulator - the 7805 is a +5v regulator, so is not the right one. The 7905 is the -5v version. But I need to check mine, I'm surprised if they used the 78xx/79xx regulators, and would expect LM3xx versions. I may be motivate to pull mine out this weekend for a listen again, and will check my WS3 if I do.

On the tants, that's just local decoupling - 35v is right, 4.7uF is possible, but I'd suggest 10uF (which is what Naim use) - note they are polarised, note the position of the + sign over one leg...and note on a negative rail it will be connected to ground. If you trace back, you'll find one of the big electrolytics is also being used. I'd be changing this too...and unless you have a way of measuring the others...and intend keeping it...replace the others too just for safety.

Edit to add: I'm a hoarder too. Just forced myself to sell off a few bits, which was a nice CHF 1'000 income...scouting for more faulty stuff now to replace it, LOL :)
 
For the socket, yes, any DIP28 IC Socket.

On the regulator - the 7805 is a +5v regulator, so is not the right one. The 7905 is the -5v version. But I need to check mine, I'm surprised if they used the 78xx/79xx regulators, and would expect LM3xx versions. I may be motivate to pull mine out this weekend for a listen again, and will check my WS3 if I do.

On the tants, that's just local decoupling - 35v is right, 4.7uF is possible, but I'd suggest 10uF (which is what Naim use) - note they are polarised, note the position of the + sign over one leg...and note on a negative rail it will be connected to ground. If you trace back, you'll find one of the big electrolytics is also being used. I'd be changing this too...and unless you have a way of measuring the others...and intend keeping it...replace the others too just for safety.

Edit to add: I'm a hoarder too. Just forced myself to sell off a few bits, which was a nice CHF 1'000 income...scouting for more faulty stuff now to replace it, LOL :)

Thanks for your reply and all the info/advice. I will double check my reading of the numbers on the regulator, I can't rule out eyesight error there. I want to keep to an absolute minimum what I have to do, as I know myself well enough to know that the more there is to do, the less likely I will do any of it at all. Baby steps are required, I think, so I will look at de-soldering the TDA1541A from the Arcam and the Woodside (respecting necessary anti static stuff which I guess is something I should think about) and replacing just the regulator and tants immediately around the regulator to begin with. Once I have actually heard the DAC in action, which I hope that doing the aforementioned will get me into a position to do so, I can then look at doing more in terms of other tant replacement and the larger capacitors too at some point in the future.

I picked up from reading your previous thread that you linked to earlier, Mike P's suggestion of cutting the legs on the faulty TDA1541A and the de-soldering a leg at a time in order to remove it, I will do this so as to minimise chances of me damaging the board (that's the plan, anyway). Any other tips to safely remove the good TDA1541A from the Arcam?
 
That's a much safer way of removing the DAC chip. However, I'd want to be very sure that S1 chip was dead before destroying it.

Maybe treat yourself to some chip quik and whip it out intact, just in case.
 


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