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Philips DAC960 rebuild

Mike P

Trade: Pickwell Audio
Here I go again...


My newest project is a rebuild of a classic Philips DAC960, which I've taken on for @k90tour (Richard).


Richard was already quite smitten with the Philips but wanted to check if it I could squeeze a bit more performance out of it. I'm glad he did because there are some very substantial gains to be had (read on).


I'm really not sure where to begin with the one, except to say that it must be one of the strangest and most perplexing jobs I've ever dealt with!


Someone else has been at Richard's DAC960 before me and they went berserk replacing everything they could. And I really do mean everything. The bizarre thing is that they've replaced stuff without any consideration as to whether or not it needed replacing, or if there's any benefit in replacing it. And they've simply replaced parts based on the value without any consideration of the type. For example, they might have replaced a film cap with a ceramic etc.


Here's an overview of Richard's DAC960

20210512_091746 by Michael Pickwell, on Flickr


And here's a pic of the internals of my Marantz CDA94 to show you how it looked when in left the factory (more or less).

20210512_091750 by Michael Pickwell, on Flickr


As you can see the whole thing has been 'carpet bombed' with the same blue BC Components caps. I'm certainly not against recapping a piece of kit that's this old but the capacitors they've used are not up to the same quality as the originals. The DAC960 deserves better and I shall be taking most of these back out and replacing them with top quality and better sounding top spec audio grade capacitors (like it had originally).
 
And here's where it gets really bonkers - the DAC board.

DAC and analogue filter on the Philips
20210512_091944 by Michael Pickwell, on Flickr

And on the Marantz (not 100% original)
20210512_092031[873] by Michael Pickwell, on Flickr

The first thing you'll notice about Richard's DAC960 is the lovely 1997 S2 double crown DAC chip. You have no idea how much I want it!.

But look closer...

The original high quality 100nF polyester film bit decoupling caps around the DAC have been replaced with....100nF Wima polyester films. No harm done but why bother?

All ceramic caps have been replaced. Again, no harm done but why?

All of the resistors have been replaced.

The diodes have been replaced.

I think the transistors have been replaced too.

The original JRC5534D op amps have been replaced with....yes you guessed it JRC5534D.

The film decoupling capacitors around the DAC have been replaced with MLCC's.

The DEM oscillator cap has been pointlessly replaced, and only with a ceramic too.

And here's the really painful bit...

The 2% tolerance polystyrene foil capacitors in the filter have been replaced with Wimas (I could have cried).:(

And the precision polypropylenes in the filter have been replaced with ceramics. Yes, you read that correctly, ceramics! :eek:

I shall be doing my very best to reinstate parts of the original quality.
 
Wow. The DAC960 is my dream TDA1541A-based DAC- I know it is extremely similar to the Marantz CDA94, but those 1980s Philips looks and colour scheme are just heavenly to my eyes. (This is k90tour's actual unit):



Following this one with interest.
Super nice to my eyes as well and will never look outdated.
 
The DAC board.

20210515_132426 by Michael Pickwell, on Flickr

Every electrolytic, bar one, has been replaced with a top quality audio grade part. Mostly a mix of Elna Cerafine and Elna Silmic but there are a couple of Nichicon KZ in there too. Some of the values have been increased too.

The polystyrene capacitors in the output filter have been reinstated, as have the other film caps.

The 100nF Wima bit decoupling matched but two of them didn't have the same markings on their tops. Whilst that obviously has no functional significance it's the kind of thing that gets my OCD going. I removed the two non-matching caps and moved the ones on the MSB pins into their place. I then replaced the caps on the MSB pins with larger 470nF Wimas.

The ceramic DEM oscillator cap was swapped to a Wima FKP 680pF.

The two big smoothing caps are now 8200uF Mundorf M-Lytic AG.

The cables were all 'dressed' to match the layout in my Marantz CDA94.

Any suspect solder joints reflowed with fresh solder. Especially those those around the input/output connections and anything that gets hot.

20210515_132458 by Michael Pickwell, on Flickr

And that's it. Over sixty new parts fitted and that's one Philips DAC960 restored back to it's former glory and even better than when it left the factory. :)

20210515_140146 by Michael Pickwell, on Flickr
 
Quick question : were the boards in good condition or you had to do a few bypass with small wires ?
No lifted pads or traces and overall very minimal damage to the boards from the previous recap. Whoever did it was very neat good at soldering, they just made a lot of very poor component choices and replaced loads of stuff that didn't need replacing.

There are a few small jumpers and cut traces but it it's a factory revision. Both my CD960's had similar.
 


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