Marantz CD-63SE manufacturing error (resistors instead of inductors in DAC filter)? - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 4th November 2010, 12:20 AM   #1
diyAudio Member
 
Join Date: Nov 2010
Location: London
Default Marantz CD-63SE manufacturing error (resistors instead of inductors in DAC filter)?

I have always felt that my Marantz CD-63SE was a bit 'toppy' in the high frequencies, so I decided to look in to it, and perhaps mod it. After inspecting the PCB and its components, it seems I don't have the 220uH inductors at L601 and L602. They are 2.2 Ohm resistors instead! There's no question about it. One measures 2.3 Ohms on my meter (taking tolerance of the resistor and my meter into account, that's okay), and they have the colour coding of: red, red, gold, gold. There is no question about that either - definitely two wide rings of gold. So even if it was an inductor, it would be a 2.2uH one, and not 220uH as it's supposed to be. And they are identical in body colour and shape to the adjacent resistors. All other passive components seem to be the correct value as stated in the service manual circuit diagrams.
Should this be right? Does anybody know of a change of design Marantz performed during the run of this model? Without the gentle curve of audible high frequency cut (made up for by the slight lift of the other aspects of the filtering) leading to a notch at 350kHz, no wonder my machine sounded so toppy and fizzy!!
I suspect the wrong component may have been loaded into the machine that populates the empty PCBs during manufacture....
Anyone know for sure, or would hazard a guess for me?
  Reply With Quote
Old 4th November 2010, 12:10 PM   #2
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
A frequency sweep with a test disc and 'scope will confirm if the response is incorrect.

I would doubt very much there is an error, more likely a production change if they really are resistors. Usually full copies of service manuals and their service bulletins detail changes with reference to serial number.
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 4th November 2010, 02:32 PM   #3
diyAudio Member
 
Join Date: Nov 2010
Location: London
Although I appreciate your reply Mooly, I wish I could share your trust of manufacturing and industry... Many, many experiences of mine and others are to the contrary!
Even if the response measured flat as a pancake to 20kHz on the 'scope, the very presence of the inductors is critical to generating a notch out of the frequency range at about 350 kHz (8* Fs). Without these, the following circuitry is blasted with a much higher level of 350 kHz oversampling noise. Of all the mod'ing articles and contributions that I have searched for from the internet community about mod'ing this particular CD player (both on diyaudio and beyond, and there are a lot!), none mention removing the inductors, and none mention the radical design change of them being removing by Marantz either. In fact the many references to the inductors from other mod'ers out there are about upgrading to better quality inductors, and additionally changing the value of them, in concert with other slight changes in the filter to nudge the roll off curve about, while maintaining the all-important 350 kHz notch. Considering how little a 2.2 Ohm resistor would do in this circuit (and how much cheaper it would have been for Marantz to simply put a 0 Ohm wire link in instead), I'm really beginning to warm to the idea of it being a manufacturing error.

Anyone else?
  Reply With Quote
Old 4th November 2010, 03:00 PM   #4
diyAudio Member
 
Join Date: Nov 2010
Location: London
I also forgot to add Mooly, that I did check the service manual, and the addendums I have for the CD player, and none of them refer to replacing the inductors with a resistor. I also have thought, that considering the extreme rarity of using very low value impedance resistors (sub 10 ohms) in low power solid state audio circuits, and considering how close the colour codes are, it probably is a mistake on the component suppliers side, not Marantz who simply failed to spot it. I have EXTENSIVE experience of being offered the wrong value components when purchasing, especially from a local Maplins (more often than not in fact! I eventually got into the habit of borrowing a multimeter from their own shelves to test components every time I went in to get passives!) but even professional industrial suppliers like RS components have fallen foul of this, for me....
  Reply With Quote
Old 5th November 2010, 08:12 AM   #5
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
If you are in doubt the only way is to take one out and test it using either an L meter, bridge, or a sig gen and scope and rig a simple LCR network up. A small 220uH coil would have a DC resistance of around 2 to 4 ohms anyway, so the fact they actually measure around 2.2 ohms doesn't in itself prove much.

You will never be happy unless you prove it to yourself. You have the advantage of having the unit in front of you too. If it were a manufacturing error, it would affect a whole production run, not just yours, so many would be affected. Not saying it's impossible, but it's up to you to prove it now.

Maplins and other component suppliers are a world away from manufacturing... as an electronics engineer I can only recall one instance of an incorrect part being fitted (as opposed to mods that appear in production) and that was a Toshiba TV years ago that had 1N4148 diodes fitted in place of a ZTK33 voltage reference... they all had tuner drift as a result.
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 5th November 2010, 11:39 AM   #6
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
I always though it was a bad idea to make small inductors which look like resistors!

You need to check the components, as Mooly suggests, or use an oscilloscope to compare the 'before filter' and 'after filter' signal.

This unit might not have been built by Marantz, but by a factory somewhere else which was contracted to do it. Modern companies are often 'virtual', so their products never actually exist (except as prototypes) in their own premises. Brand 'A' has their products designed by 'B' and built by 'C', then stored in a warehouse by 'D', who responds to orders from distributor 'E' to send to shops 'F', 'G' etc. 'A' might never check that the products delivered to 'G' are actually as they should be, unless a customer complains. 'C' might not be too bothered about getting things right, as it is not his name on the box, so as long as gross errors are avoided (i.e. the thing vaguely works, and doesn't explode) he can be confident that 'A' won't check.

One interesting thing is that these mistakes almost always involve a cheap component replacing an expensive one. Must be coincidence!
  Reply With Quote
Old 5th November 2010, 01:28 PM   #7
SimontY is offline SimontY  United Kingdom
diyAudio Member
 
SimontY's Avatar
 
Join Date: May 2003
Location: Sheffield, North England
Send a message via MSN to SimontY
Hi,

Indeed, my first question would be have you measured the inductance? If you don't have an LCR meter/bridge maybe you can borrow one.

Secondly, it's been pointed out by some who have measured and/or simulated it that the DAC filtering on the CD63 doesn't generate a flat response, but one that peaks in the treble about 1dB IIRC. This is partly why some people have changed one of the capacitor values to reign it in. I would like to say that, personally, I don't feel a small alteration here will fix the sound of this cd player. You need to spend time reducing the psu noise and jitter and, crucially, regulate the servo driver op-amps in order to remove the harsh, thin and woolly sound and lack of detail.

Thirdly, the CD63 will always have a slightly bright and upper-mid-forward sound, it can't be completely tweaked out. I assume it's the nature of the chipset.

Simon
  Reply With Quote
Old 5th November 2010, 06:03 PM   #8
diyAudio Member
 
Join Date: Nov 2010
Location: London
Hey! Thanks for the input, people. Of course I've definitely got some testing to do. But first:

Mooley - I agree about the low impedance of inductors, and that it is not conclusive that it's a resistor from that. But considering the colour code definitely is red, red, gold, gold, it is therefore 2.2 something (ohms, or microhenries) , unless there is a colour coding error on the correct component. Still an error there though! I did check many of the inductors on Farnell's website (including those suggested by some other mod'ers lists of components to upgrade to), and the DC resistance hovered between 5 and 9 ohms... If it is an inductor, it's a bit of a coincidence that its DC resistance matches almost perfectly with the colour code on its body, (and even then it would be out by a hundred fold from the 220uH inductor that's supposed to be there)... But testing it is the DEFINITIVE way, I agree. Now I have an oscilloscope, a multimeter, and stacks of passive components around my workshop (but no signal generator, except for a CD test disc with audio frequencies on it which I play through another CD player, if necessary). Could I go about setting up a rudimentary rig to test if it is an inductor (and hopefully its value too, although at this stage that's not so important) with the above ingredients, and if so how? I assume it could be basic enough to be described in writing, and as we're on the very edge of my relatively modest knowledge of electronics, I'd be most grateful! I did think that I could lift R607 from the circuit so as to form an RLC network after the first opamp based filter, and could raise C605 to 1uF from 1pF. That would cause the response to fall away rapidly at from as little as 10Hz and go on to cause a -90dB notch to form at a few kHz instead of 350kHz (which would rise back up 20 dBs or more above that) - if it was an inductor. However if it wasn't an inductor, and was effectively just an RC network, then the response would just gradually roll off from 10kHz or so a few dBs. I could use my test disc and 'scope to measure for that. Have I got all this right?

DF96 - Yes.... This is my experience of things... It used to amaze me that life is as error free as much as it is, with all those areas for mistakes to creep in.
I used to have a strange desire years ago for reading up on aircraft disasters and their causes, and you wouldn't believe how many aircraft have been downed due to the communication breakdown along the chain of engineers in construction and maintenance, and how tiny and trivial some of those errors are, with such devastating consequences sometimes many years later. And that's in something as serious as aviation. God knows how many errors actually occur in consumer electronics! It will be interesting to see if my current issue is another one though...

SimontY - Thanks for the input. Definitely some testing coming up. I've since also been looking into the various improvements this CD player can garner. I'll take your advice into consideration for some of the more up market tweaks, but first things first!
  Reply With Quote
Old 5th November 2010, 07:06 PM   #9
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Do you have frequency sweep on the test disc ? or if not what frequencies does the test disc have ? (preferably high such as 10khz etc)
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 5th November 2010, 07:27 PM   #10
diyAudio Member
 
Join Date: Nov 2010
Location: London
Hi Mooly,
Yes, there are sweeps. It's the Sound Check CD by Alan Parsons and Stephen Court mastered at Abbey Road. I actually got it from RS - stock number 245-376. There may be more on it at RSs website, but it has:
a variety of pink noise bands and phase test combinations,
22 separate 1/3 octave band tests from 20 Hz to 20 kHz, and sweeps from 20 Hz to 8kHz,
spot sine freqs from 60 Hz to 15 kHz in 11 steps,
sine sweep from 20 hz to 20 kHz

Plus other stuff, but the above is what I think is what we're interested in. Which one(s) should be used?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Marantz CD 63 'Radial error' dingzie Digital Source 2 16th March 2007 07:01 PM
Modded Marantz 63SE vs. NAD 542 Samuel Jayaraj Solid State 4 13th May 2006 08:00 AM
Tray opening error MARANTZ CD-94 EIRA Digital Source 1 18th February 2005 12:04 PM
Marantz 63SE - Is it a candidate for mods? Bill Fitzpatrick Digital Source 16 24th September 2004 01:21 AM
Aleph 3/Marantz CD-63SE Tweaks/DIY vsr123 Pass Labs 14 31st December 2003 09:13 AM


New To Site? Need Help?

All times are GMT. The time now is 05:50 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2