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Hello Pedja,

Voltage at R107 and R108 is 2.5 VCD; Pin 1 & 2 of TDA1541A have ~5 VDC ... that seems to be too much, right?

Best, Christian

R101 & R102 3.3V; Supply at quartz 5 VDC (quartz is 5 V type)

Yes, it most probably means that the flip-flops output constant 5 V DC ("high"). So the problem is apparently with reclocking part.

What flip-flops and oscillator exactly do you use?

Hello Pedja,

I got the clock from our mini-group-buy so I unfortunately don't know. Is far as I know it is as suggested in your PDF. There is "DC P2SR // 50M // 01" written on it.
The flipflops are Philips 74HC74D.

Unfortunately, the new old scope i got today is broken ... and while testing i missed an interesting ebay auction ... i will see.

Best,
Christian

I have none 50 MHz Crystek at hands to check the marking, but that's it probably. A 3.3 V DC you measured at its output is strange though, it points out either significantly asymmetrical waveform, or some problem. Otherwise you should expect half supply voltage here too.

Now, it is hard to go further without a scope. And 10 MHz would be useless here anyhow. Yes, interesting stuff can pop up at e-bay, or you can try to borrow something... But there is something wrong with reclocker for sure.

Hello Pedja,

unfortunately i can not borrow a scope around here. I guess i will have to buy one. 35 MHz will be sufficient in this case, right? As the aya dac is promised so play in the USD 1000 league a USD 500 scope has to be within the budget

Thanks for your effort on helping me so far!

Best,
Christian

Hi Christian,

US$ 500 will buy a new 35 MHz scope. If you watch carefully, you can find something second hand in very good condition, 50 MHz or more, for 100 EUR or a bit more. And it will work not only to debug this DAC, but will serve you in the future too.

(Of course, you can change all the parts in the reclocker for a fraction of this money, and the oscillator is in my view prime suspected, but it will be kind of shooting in the dark.)

As for the required bandwidth... The frequencies you have here are ~2.8 Mhz (bit clock) and 44.1 kHz (word select) at flip-flops input and outputs. This is when receivers locks. When it looses the lock, the frequencies are about one half of these, so ~ 750 kHz and ~ 11 kHz. A 35 MHz is obviously enough to check this. However the frequency of the oscillator driving the flip-flops is 50 MHz, so it will be barely visible at 35 MHz scope, at best.

Hello again,

a friend came back from a long holiday ... he has a 100 MHz scope, I have a date on tuesday He is quite experienced in debugging audio and dvb devices, so this will be double help ...

I will report then. Fortunately I have a second clock etc so there is a chance to get the dac working.

Best,
Christian

I am placing my bets on it being a problem with the clock - poor or incorrect solder joints. You can't make it without solder paste or at least using flux. Very easy to bridge a pin to the case, which is also connected to ground. (yes I have been there and done that) The other SMT parts are easy, but the clock's ground pin is connected to a large ground plane and it was not easy to have the correct amount of heating.

Pedja - what method have you used to solder the clock? I believe it's best to reflow here.

Christian,

Waiting forward to the results, possible further questions etc...

Michael,

You're right, and that's what I do, but it is possible to do this successfully with relatively narrow soldering tip too, as the pads/contacts are also partially accessible when the part is in place.

Hello,

fortunately, there is access ... and the pads of the clock have a small contact area on the side of the device so i was able to resolder one joint that wasn't properly done... i thought i had some training in doing that but who knows. To make it short, even without scope I could find the defect and now my AYA DAC is playing music! Thanks for your help again! (And thanks for the project in general)

I will do some comparisons to my CS8420-DF1704-PCM1704-OPA627-DAC and report my impressions. Until now the aya dac did play three CDs or so and it started already promising.

I used all parts as suggested in the PDF despite some capacitors. So all 0.1uF and 1uF decoupling caps are WIMA MKS (=MKT), the smaller electrolytics are Oscon or replacement types; the larger electrolytics are low ESR types of different brands. The film caps are non-inductive (EMZ) KP or KS, some silver mica. The coupling caps at the output are Black gate as suggested in Pedja's parts list. All resistors in digital and analogue signal are non-inductive (Allen Bradley, PRP, Vishay RN55D), power supply etc. have standard 1% metal film resistors. I use one special wound torodial transformer.

Is there a quick-and-dirty way to connecting two DACs to one source at once (for comparing...)? I am afraid just paralleling would not work. Right?

BTW, what CD player or DVD player _with silent drive_ is a good source for the AYA DAC? I would like to build a one-chassis player from it.

Best,
Christian

... i just won an ebay auction on a 150 MHz tektronix scope ... hopefully I will need it and use it some time ...

Oh, well...

Are you using MKS instead of BG as those 14 TDA1541A decoupling caps too?

As for the resistors, I not at all inclined to metal films. I've tried using PRP for some time but I’ve given up of them too.

Plain paralleling will surely spoil the impedances, but you can try some 75 Ohm T-adapter.

Honestly I’ve never had a problem of this kind with regular audio CD drives. PC drives are different, they run at high speeds and produce mechanical noise, but dedicated audio drives are for me normally silent enough.

Anyhow, to make some one chassis player, if you start with some machine which already uses I2S it will simplify the things. Generally, old Philips machines with CDM-0 and CDM-1 are in my view about unbeatable as a basis, and you can count also those using TDA1540, as it is easy to turn TDA1541A into synchronous mode and make it compatible with them.

And, wish you a happy DAC and scope.

Hello Pedja,

yes, MKS also used for decoupling the TDA.

So you usually use carbon film resistors and match them yourself?

Agreed on audio CD drives; I would like to have one capable of playing CD-RW, so the old ones would probably be not working for me. I tried some DVD drives but most of those now have PC drives and they are producing mechanical noise. DVD players are quite cheap and the data quality should be OK, so that was why I thought of DVD drives. But maybe this is not the right place for that discussion as this is the audial forum here ...

Best,
Christian

Hello Christian,

Maybe you shouldn't miss last chances to get some Black Gate NX. The stocks are getting emptied slowly and there won’t be another chance then.

Allen Bradley is where I am currently at. I will probably even replace Rikken used in the Model S up to now with AB. They are a bit lazy but still are sweeter than Rikken, and latest Model S has quite open tonal balance, so everything gets in place with AB. Both Rikken and AB are carbon resistors. Rikken tolerances are tight enough, but AB must be matched when used as I/V resistors.

I don't use CD-RW myself, so I'm surely not the best person to talk on this, but Philips VAM mechanisms should be able to read CD-RW, so some newer Marantz CD players can be candidates.

Hello Pedja,

I understand your advice on the black gates that you thing these are much better than MKS. OK, so i will give them a try.

I will look for a marantz player, I like some of the front panel designs, so I have to put in the AYA dac only in order to get a nice cd player.

Best,
Christian.