Finally, an affordable CD Transport: the Shigaclone story

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stefanobilliani

Member
Joined 2002
kevinkr said:


This unit is box stock and the resistors I used for the spdif level reduction are quite dreadful.. :D The original values I chose are not the right ones for the amplitude I measured which was 5Vpp...
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I must say in my tests yesterday I preferred to not have the parallel resistor after the series to ground . Guess why ? becouse the dac has its own 75ohm resistor in parallel at the input . That is at the other side of the cable . After some good listening I am going to choose a value for just series at the output that will vary from a min of 47 ohm to max 100 ohm . Will let you know .
 
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stefanobilliani

Member
Joined 2002
kevinkr said:
Here is a picture of the RCEZ32 electronics in operation
http://img443.imageshack.us/my.php?image=rim00067xz5.jpg
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There seems to be too much un necessary stuff there .

I have been investigatin on the nature of the Motor drive Ic becouse I wanted to separate the supply of it , from the rest of the board ( I am planning to have a different supply for all the 3 ICs ) .
So my third mod was to have 2 supply . It is not very difficult do mod in that direction . I had a listening session with " steely dan -Aja " like never had before .

The ride cymbals on " black cow " are like planets floating out of the speakers , the sax on " aja " is so sweet and so well placed / non agressive in the scene that actually I was seeing it in front of me . The drum kit in " home at last " is fantastically present the bass drum finally sound like you can feel the tension of the skins . And it seems like sitting at least at the side of the drummer . Wow .
I am curious to know your impressions .
Just to let you know , I am using the DAC form Rockna , with the AD1856NK ( 18 bit ) ( thank you P D ) in non os mode . Eavily modified on the PS . That dac incorporates a reclocking circuit . I am a fan of " in sinc " connections when speaking of clocks (infact previously the dac shared the same clock of the dvd source ) , but in this test I am quite positively impressed and curious on what the freshness and dynamics ( which are very correct ) will give to the long term listen .
 
johnm

johnm

Member
Joined 2003
I've just got the main CD board out now and I'm going to be replacing some capacitors today or tomorrow.

However I just noticed that both motors are subject to a little 'rocking' movement if you wriggle them gently. I'm going to desolder them, and then make sure they're soldered down again firmly against the circuit board this time. Obviously as-is the spinning disc will create undesirable vibrations which isn't good.

I'll probably put some hot melt glue or blu-tac around the motor as well to further damp vibrations.

If I put my finger onto the cd hub, I can rock the motor left to right - there's about 0.8mm 'play' from side to side.

Cheers,

- John
 
okapi

okapi

Member
Joined 2004
northwestern.edu/neurobiology/faculty/spruston/People/jarsky.htm
johnm said:

However I just noticed that the both motors are subject to a little 'rocking' movement if you wriggle them gently. I'm going to desolder them, and then make sure they're soldered down again firmly against the circuit board this time. Obviously as-is the spinning disc will create undesirable vibrations which isn't good.

- John
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Hi John, the motor movement you are referring to occurs when they are screwed to the mechanism? if not, it might be possible that loose coupling between the motor and control board may reduce vibration transfer into the control board.

Kevinkr - thanks for posting the pics
 
Peter Daniel

Peter Daniel

Member
Joined 2002
audiosector.com
Paid Member
okapi said:
Hi John, the motor movement you are referring to occurs when they are screwed to the mechanism? if not, it might be possible that loose coupling between the motor and control board may reduce vibration transfer into the control board.
Click to expand...

Yes indeed, I wouldn't worry about it. In fact, attaching them more securely to the boards may influence things in the wrong direction.

I tried to damp the transport frame too and it didn't work well.
 
johnm

johnm

Member
Joined 2003
Just a warning to those who have yet to de-solder the caps on the circuit board, those tracks can lift VERY easily. Be absolutely sure all solder is sucked up before wriggling those caps out. I lifted a solder pad but VERY luckily for me it was for a cap that was to be removed and not replaced anyway!

Peter I'll leave the transport undamped then - certainly a case of 'good vibrations' ;)

- John

P.S. Regarding the motor 'vibes', would it be an idea to totally unsolder/decouple the motors from the lower curcuit board, so that they are only attached to the laser mechanism only by those four grub screws? This would allow the lower board to be mounted seperately to the laser mechanism...
 
johnm

johnm

Member
Joined 2003
For the record - I HATE BL**DY SMT CAPACITORS!!!!!!!!!!!!!!!!!!!!!

If I haven't done any heat damage to the circuit board I soon will at this rate! Can't get the bug*ers off - tried one iron, two irons, tweazers... aghhhh!

I think I'll just leave the two remaining ones in - hopefully they won't affect the performance that much.

- John
 
Q

quan

Member
Joined 2007
shigaclone

Yeah, i had to snipped them off -those small capacitors- luckily they are the ones not required.
Any comment regard putting a better clock with its own power supply? I saw a picture in the original Polish forum-using DIY-HIFI supply clock . Wonder how much a improvement ?
 
kevinkr

kevinkr

Administrator
Joined 2004
kta-hifi.net
Paid Member
One of the biggest improvements so far in my experiments with the RCEZ32 was to replace the 2200uF cap in the psu with a pair of better 1000uF electrolytics in parallel. Quite audible.

So far I have replaced the resonator with a 16.9344MHz crystal of the type recommended by Peter. Citizen CSA309 16.3944MHzMABJ-UB..

I replaced a couple of the 10uF caps the LA9242 servo circuitry (not psu bypass) with BG.

I also replaced the 1000uF/16V and 0.1uF cap filtering the supply to the LC78629 with just a single 47uF/16V BG.

The this unit requires 12Vdc to be always on and turns the +8V supply on and off.. I have hard wired the cd mechanism directly to the 8V regulator. I will build a new supply that is compatible with the old one with two separate 8V supplies on separate windings which will be both controlled by the 12V control signal from the audio board. I have removed the power amplifier from the audio board and will eventually remove the remaining chip (digital vc) at some point. I could replicate all of the power circuitry at some point, but this seems unnecessary as eventually the mechanism will have a totally isolated by 8V supply and just the control lines connecting it to the other boards.

It already sounds much better than the stock unit did last night. I think the Sony is better still, but for a $45 investment plus a few more $$ for the parts I've installed so far it is pretty surprising.
:D
 
S

stefanobilliani

Member
Joined 2002
I just succeded in separating the supply in 2 parts . If you back engeener a little you will see that the 8 volts goes directly to the Motor Driver . The other 2 chips powered by a little stage with a PNP transistor ( the BJT depends itself from the motor driver ) that regulate the voltage to 5V . I think separating that would be a good move . Now is too late for a serius listening , will do that tomorow .

:drink:
 
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