Philips CD104 tweaks

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#562
Yesterday i finished my adapter that enables me to get rid of the SMD caps and replace them with WIMA MKS02. Few more filtering caps are placed near the IC. I used tantalum ones. This is what it looks like on the victim - my beloved Grundig CD7550 😀







Upon future interest I will upload the BRD file for the PCB and will give further information.

As for the sound. It doesn't give that great improvement stated by many people around the web. It gives some audible improvements tough. Few masked details and nuances come up and give a bit richer sound image.

Please don't pay attention to the misplaced 220nF caps. They are now 470nF. All others are 100nF. The two additional filtering caps are 33uF tantalum. 😀

Regards 🙂
 
#563
I need help with my CD104: Trying to recap, I foolishly managed to destroy one SMD cap very close to the clock. Now unfortunately I am not skilled enough to read schematics, but I'll try to attach a pic and perhaps somebody can provide me with the value of the destroyed cap.

Greetings from rainy :bawling: Germany,
Wolfram
 
#566
Hey guys.

Just want to let you know, that I have a CD-104 which in fact had the "need-to-warm-up-for 30-min" issue.

It is now working perfectly.
All I did was resoldering everything on the PSU board and the large griplets on both the mainboard and DAC board.

It's a bit irritating because I first had looked this CD-104 out to be just a sparepart machine.
Darn. What to do but listen to it.
It sounds absolutely great 😉

I have my CD-100 on the table disassembled waiting for new caps to arrive. Hope they will cure the buzzing/humming noise from it.
BTW. Those axial caps....can I replace them with ordinary radial caps ?
I'm thinking of the blue axial ones, not the yellowish.

TIA
 
#569
Valve output

Hi All,

This thread has been lying dormant for a while and in a bid to resurrect some interest here is a pic of my recently completed valve output for a CD 304, note the opamp out removed and a SRPP 6N2P (see lampizator.eu) circuit added on an attached base, with nos dubilier 2.2uf capacitors.

As for the sound, to my ears it is more refined than a AD826 or OPA2134, this together with the NOS mod seems to have removed that HF grain.

I'm still playing with the I/V resistor, at the moment it's 20 Ohms.

I curious to hear what people are using as an output stage for the beloved TDA1540

Cheers,

Richard
 

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#578
Replaced caps on the humming CD-100.

Turned out, that the replacement didn't cure the machine at all.
Resoldering the DAC board cured this case instantly. 😉


I think we have a problem with these machines.
Someone mentioned an issue with the treble not being exact in the middle as intended, but sounding somewhat off-phase or wishy washy.
I've got the same thing going here and noticed it for the first time a couple of days ago on "Clouds on my Tongue", song #10 on [Tori Amos, Under the Pink, 1994 Warner Music].

Wow. That's not what I would call "Precise treble performance", Gentlemen.
I had to go over it again and had it also played on a CD-207.
The problem remains on the CD-207 as well.

Is this a general issue with the TDA-1540/SAA70xx based DAC or are these DAC's so good that they discover bad CD-mastering ? 😀

How well does the 14-bit NOS mod perform ?
Is the off-phase treble also an issue after the 14-bit NOS mod ?
 
#579
Due to the subharmonics (Bernard tested that) of thetda1540 music can sound rather good. But14 bit compared to 16 or even not to mention 24 bit nowadays has 1 big contra: treble is suffering from detail. That's the reason why i never installed the 1540 in my listening room.
 
#580
Well I did another comparison.
Played the CD on a Philips AZ-something (a portable CD from 2000/01)
Still this off-phasing treble continued.

I'm sorta puzzled about this. It's pointing towards being a bad CD.
Need to listen on other machines before making any judgement.
 
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