Finally, an affordable CD Transport: the Shigaclone story - Page 443 - 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 9th March 2011, 04:03 PM   #4421
johnm is offline johnm  United Kingdom
diyAudio Member
 
johnm's Avatar
 
Join Date: Sep 2003
Location: Hampshire
Quote:
Originally Posted by commstech View Post
John, go to post #1517. get a small heatsink if u do not mount onto chassis.
"On startup it peaks briefly at 450ma and then settles in to 200-210ma DC while running"

Many thanks

- John
  Reply With Quote
Old 9th March 2011, 06:02 PM   #4422
diyAudio Member
 
Join Date: Apr 2002
it seems that woodturner aka fran may be onto something with the SPDIF attenuator.

I initially used it with the 300/100 resistor combo, but frankly I could not hear any change when going from no attenuation to -10dB to -15dB

Reading fran's experience, I decided to bypass the 300/100 combo. Then I added in the 10db attenuator and listened. Something had changed for the better (vs the 300/100). The I added the 15dB attenuator and heard a further change.

The sound seems to open up with the attenuators in place, another so-called veil being lifted. Highs are cleaner and bass has been clarified further.

will do more listening...
  Reply With Quote
Old 10th March 2011, 11:55 PM   #4423
diyAudio Member
 
noSmoking's Avatar
 
Join Date: May 2010
Location: Texas
Default looking good !!!!!!!

Quote:
Originally Posted by Dr.H View Post
Hi nosmoking, I've done the following:

300/100R spdif mod
1. Mains filter
2. Removed choke, C916 and C952 and bypass caps
3. C916 replaced by a OSCON 47uF, 25V cap
4. 300/100 on digital output to 75R BNC connector
5. LM317 based 8V supply with around 2200uF pre and post regulator filtration
6. It is "naked" and sits on a bit of bubble wrap at the moment. No fancy mech isolation etc.
7. Supply 5V off ALW reg

I want to try:
SPDIF attenuator
300VA transformer
Snubbers on power supply diodes
Low resistance Inductors to replace wire links
Tantalum caps to replace some electrolytics (those for PS decoupling)
Possibly a second ALW reg dedicated to one of the chips
  Reply With Quote
Old 11th March 2011, 12:06 AM   #4424
diyAudio Member
 
noSmoking's Avatar
 
Join Date: May 2010
Location: Texas
Hey,
I found a chip LA6541(only one) it was a dip can't get a smt (backordered)It's ic 903,My problem is the circuit on the data sheet and the actual circuits don't compute correctly,I have the picture peter posted and it's what I have , Would some one be willing to pin the chip out to the board as some traces are missing from the board and when I trace the ones that the data says ,they don't go there,like ic 903 pin 2 goes to Lc 78601 pin 32 but no it goes to led segment on the board,,,,,,,,Any help would be appreciated,
THANKS,
A source for a new controler board would fix this TOO,lol.
  Reply With Quote
Old 11th March 2011, 12:20 AM   #4425
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Dr. H - glad you have more or less heard what I have. As I understand it, the RF attenuator is perfectly impedance matched, so it reduces reflections that bounce from one end of the cable to the other. If one of these "bounces" hits as the signal is going from 0 to 1, it causes jitter. So by using the attenuators, these "bounces" are cut. In the shiga, we are lucky - we have a high level signal, so can afford to, or want to, cut the signal.

They actually don't cost much more than some fancy riken or caddocks when you factor postage..... and best of all, what you heard Dr. H - thats what you hear when you use them on most digital sources. Squeezebox, CDPs, etc etc etc


Fran
  Reply With Quote
Old 11th March 2011, 12:21 AM   #4426
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
No smoking - could you get/make a DIP to smt adaptor? Or get someone in Canada to post you over one?
  Reply With Quote
Old 11th March 2011, 12:48 AM   #4427
diyAudio Member
 
noSmoking's Avatar
 
Join Date: May 2010
Location: Texas
well yes probably can but I will hand wire it if I know exactly where they should connect,
I am finding it confusing when they don't match up,The sheets shows one way and the board trace goes to a different location,I'll try a different schematic,maybe that's the problem,

Thanks,
  Reply With Quote
Old 11th March 2011, 01:13 AM   #4428
diyAudio Member
 
noSmoking's Avatar
 
Join Date: May 2010
Location: Texas
I can't put the sheet up for some reason,but here is a link to la6541D,Audio Lab of Ga
Would someone compare it ,The smt and dip are pin to pin identical,but 1c 902 the trans is on pin 12 the picture peter posted 901 is on pins 5 and 6,this is what's got me spoofed,so I wonder if the other pins are right?
Thanks,
  Reply With Quote
Old 11th March 2011, 01:47 PM   #4429
diyAudio Member
 
Join Date: Apr 2002
Default Some observations, more questions

Hi guys,
have looked at the data sheets for the chips used in the shigaclone and a few things pop out:

1. 78601e, the dsp that generates the reference clock, amongst many other things, has THREE separate 5V pins (p6=internal vco supply, p22=digital system power supply and p62 crystal oscillator power supply). The data sheet emphasises that the three pins must be at the same voltage (say 5V) or the chip will latch-up. this is decoupled by c934, 935 and after a 100R resistor by c953 nad 960.

2. As things stand at the moment, this same supply is connected to pin64 (RF system VCC) of 9242, the RF amplifier, amongst other things. There is also a pin56 VCC (servo system and digital system power).

I'd say that there would probably be some merit in supplying some of these pins (for example RF and internal VCO) from a seperate clean supply.

Also, any views out there on VREF at pin58 and the bypass cap at p57? currently, c930 and C928 decouples it. May be worth placing a good quality decoupling cap here (oscon etc).

Last edited by Dr.H; 11th March 2011 at 02:07 PM.
  Reply With Quote
Old 11th March 2011, 02:27 PM   #4430
diyAudio Member
 
Join Date: Apr 2002
something else to add is that the chip la6541 has an internal 5V regulator that generates the 5V for the other chips on board
  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



New To Site? Need Help?

All times are GMT. The time now is 11:03 AM.


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