PC input on my old 4xtda1541

[Dyolf]

Hi
I have a completely non-working Cambridge CD3, with the lovely DAC section just sitting there. Is there any easy way 🙂 to wire/rebuild the thing, so that I can use it as a dac for my computerbased music? I dont need USB input, just a digital coax would be OK.
Steen

 

[rfbrw]

Easier than Lego. Borrow, build, buy or steal some kind of SPDIF board, get the relevant datasheets and in no time at all you're done.

 

[Dyolf]

Yeah..
This was exactly the kind of answer i feared. I am not your averidge DIY forum guy with a knowledge of an electro-engineer. There are 3 main boards in the Cambridge. The top one is the dac-board, the middle must be the power supply, and the bottom makes no sense to me. What do I scrap, and what do I need?
Sorry for my ignorance.
Steen

 

[amc184]

If you don't have much experience with this sort of stuff, I wouldn't recommend you try this. The idea Ray suggested is the best option, but still won't be really easy. If you are willing to persevere, I'm sure the forum members could talk you through it though.

The other option would be to sell the CD3 and buy a kit. Even a broken CD3 should fetch decent money.

Yet another option would be to fix the CD3. How broken is it?

 

[Dyolf]

Its broken.
Both transport (CDM1 mk2) and display is dead. Selling it is not an option, then i'd rather give it away. But if anyone in here were willing to explain a new S/PDIF access to the dac, it could be fun, for me🙂, to try this.
Maybe this has been explained before, and I only need a link to another thread or site.
Steen

 

[rfbrw]

If you start with one of those TDA1543 boards found on EBay, like this one, then it becomes a fairly straightforward wiring problem once you remove the TDA1543.

 

[amc184]

Its broken

Okay, fair enough. Like Ray said, the easiest way to get a S/P DIF input is to buy a DAC kit with a S/P DIF input. This one here looks like what you want. It has the well liked DIR9001 receiver, and is the cheapest I saw when I had a quick look on eBay.

How you connect it to the DAC part of your CD3 depends on whether you want the DAC to be oversampling or not. So to OS or to NOS, that's up to you.

 

[rfbrw]

How you connect it to the DAC part of your CD3 depends on whether you want the DAC to be oversampling or not. So to OS or to NOS, that's up to you.

It would be best not to go there given the nature of the SAA7220 and the following circuitry. Rigging the output of the DIR9001 in order to bypass the SAA7220 is far from simple.

 

[Dyolf]

Okay
Now at least I'm beginning to understand the concept. A cheap dac kit from ebay, and then replace the whatever dac chip is on, with the 4x1541a.
Is it that simple?😕
My musical taste are mostly classic and laidback jazz, so from what I've read, I will opt for the NOS type.
Is there a chance that I will mess up badly when I start with this?
Again, excuse my ignorance
Steen

 

[rfbrw]

Okay
Now at least I'm beginning to understand the concept. A cheap dac kit from ebay, and then replace the whatever dac chip is on, with the 4x1541a.
Is it that simple?😕

It is if all you do is link the DIR9001 to the SAA7220.

My musical taste are mostly classic and laidback jazz, so from what I've read, I will opt for the NOS type.

Then you would have to extensively modify the circuitry that precedes the 4 TDA1541's or add the logic needed to reformat the output of the DIR9001 to match that of the SAA7220.

 

[Dyolf]

Then you would have to extensively modify the circuitry that precedes the 4 TDA1541's or add the logic needed to reformat the output of the DIR9001 to match that of the SAA7220.

The original layout from cambridge is 16xOS and i loved the sound, so I guess I'll stick to that then. You guys already recommended 2 different S/Pdif boards.
I've checked on eBay, and there seem to be loads of options. Is it the DIR9001 + TDA1543 types i shall go for, with no other considerations?
Steen

 

[rfbrw]

The only other thing to consider is MCLK signal. Originally the SAA7220 and the other upstream chips would have been driven by a 11M2896Hz crystal attached to the SAA7220. For correct operation you would need to use the MCLK recovered from the SPDIF datastream. Looking at the picture of the mini board, it looks like the pins that determine the frequency of the MCLK are tied together. They may be high or low, something that does not matter with the TDA1543 as it does not require MCLK but either way it means the wrong MCLK frequency for the SAA7220. The board would have to be modified to correct this.