NAD 319 rebuild project - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 11th January 2006, 11:27 PM   #1
cviller is offline cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
Unhappy NAD 319 rebuild project

Hi

I have an old nad 319 amplifier, which unfortunately is completely screwed up. The protect circuit would not turn off. In the beginning, it was only the relay that messed up the signal, but when I got that fixed, the voltage wouldn't drop on the TA7317 (protection circuit). After days of soldering measuring and burning components, I have come to the conclusion that I need a new psu-pcb. The only thing keeping this pcb together is the soldering mask. There is a +/-67V and a +/-60 V on the board. The 60V, which supplies the emitter-followers appears to be very stable, but the 67V running the protect circuit and signal amplification is very unreliable. This is the bottom view of the pcb:

Click the image to open in full size.

(I have added some resistors to discharge the capacitors, while trying to fix it).

The question is: Do you think I should try to make an exact copy of the old layout or should I just make sure the connectors are placed correctly?
Before I start my pcb program - has anyone else done this before? The pcb is the same as the one in nad 317.

Regards
Christian
  Reply With Quote
Old 11th January 2006, 11:56 PM   #2
Leolabs is offline Leolabs  Malaysia
diyAudio Member
 
Leolabs's Avatar
 
Join Date: Dec 2004
Location: Bukit Mertajam
Send a message via MSN to Leolabs
To be place safe,follow the old layout
  Reply With Quote
Old 11th January 2006, 11:58 PM   #3
diyAudio Moderator
 
pinkmouse's Avatar
 
Join Date: Apr 2002
Location: Chatham, England
I would ask myself, is it really worth rebuilding?
__________________
Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?
  Reply With Quote
Old 12th January 2006, 09:30 AM   #4
cviller is offline cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
I think it is worth rebuilding, because I really liked the sound when it worked.
I know there are many in here that don't like nad, but besides the bad pcb quality, I think it is a matter of taste and I think the sound is very good compared to the price.

I have another question. In the 67psu, there are some 100 Ohm fusible 1W resistors that died during repair.

The part of the schematic with these resistors can be seen here:
Part of psu schematic

I can't find the components in Denmark. Do you guys think it will safe to use regular power resistors?
Some of the resistors in the amp are "flame proof". Are most power resistors not flame proof?


Christian
  Reply With Quote
Old 13th January 2006, 08:45 AM   #5
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Quote:
Originally posted by cviller


I have another question. In the 67psu, there are some 100 Ohm fusible 1W resistors that died during repair.

I can't find the components in Denmark. Do you guys think it will safe to use regular power resistors?
Some of the resistors in the amp are "flame proof".

Hi Christian

If you can't find "flame proof" resistors , change the R203 FP resistor for the place of the R205 resistor and use a regular resistor in the place of R203 , because this last one , is not in a so critical position , as R205 , in case of a short in the + 67 Volt rail.

Cheers
__________________
Jorge
  Reply With Quote
Old 13th January 2006, 10:58 PM   #6
cviller is offline cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
Default Layout DONE!!! ;)

I have finished the all the layout work. I might change something before i do the actual pcb, but it won't be much. It took me forever, because I had to draw schematics and footprints also.

Tube dude: Thank you very much for providing a solution. It was not flame proof, but fusible, but the idea of using ordinary power transistors for the none critical parts should stil be valid.

I really hope I can make it work now. Someone interested in the pcb.ps when it's working?
  Reply With Quote
Old 1st February 2006, 03:55 PM   #7
diyAudio Member
 
Join Date: Feb 2006
Location: Oulu
I have also problems with 319 psu, and might be interested in making a new pcb. If you have finished with the layout, I'd be very glad to get that as well.

Thanks a lot and regards,
Petri
  Reply With Quote
Old 1st February 2006, 06:03 PM   #8
cviller is offline cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
I did complete the layout and I found only one mistake (the schematics from the service manual had some errors). I can correct that mistake and give you the layout. I've done the layout using the GPL program called "pcb", but I can export to ps, pdf and gerber - whatever you prefer.
  Reply With Quote
Old 2nd February 2006, 07:23 AM   #9
diyAudio Member
 
Join Date: Feb 2006
Location: Oulu
I think pdf is the best choice, I can be sure that I will get it opened.
  Reply With Quote
Old 2nd February 2006, 11:27 AM   #10
cviller is offline cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
I have placed the pdf ps files here:
PCB and schematics
(The files won't be there forever, but mail me if they are gone and you need them)

I recommend using the ps files if you have access to a postscript printer, but the pdfs should also work.

Use of this layout is at your own risk. I cannot be held liable for any damages to humans,property,animals etc., caused by using the layout. Nadelectronics holds the copyright for the schematics and layout structure. This is a reproduction of the psu-pcb and only intended for repair purposes.

The layout does work for me. The sound appears to be like before - no distortion. An important thing to do if you plan to use my layout is to make sure that there are no shorts. I had some shorts I needed to scratch away using a knife, but it might have been because I didn't gave the board enough time in the developer-fluid.
I have made most of the drill holes smaller than they should be to make sure the solder pads would be completely covered with copper, but if you do the pcb drilling your self, you can just look on the original pcb.
My program does not have a symbol for all those shorts on component side, so I have drawn them on the componentside as copper traces. You'll need to print the component side to get those locations. All components and shorts are placed very close to the original, so you can just take one at a time.
I think it is a good idea to start with all the psu stuff for the 5V, +-60 and +-67, and then make sure you have the correct voltages and no smoke.
Remember to discarge the big capacitors before you start soldering!

Why do you need to make a new pcb? Is it because the the solder pads are falling apart?
  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
ESS speaker rebuild project Bndkoss Multi-Way 4 22nd February 2009 04:07 PM
Cab Conversion, Radio Shack Project Rebuild Thor74 Subwoofers 7 12th April 2005 04:58 AM
Help with amp rebuild zeke Tubes / Valves 15 4th October 2004 01:39 AM
next project: rebuild using fisher 500c trannies zobsky Tubes / Valves 27 15th March 2004 07:58 PM
HFT-90 anyone rebuild one before? ajhawkins Tubes / Valves 10 12th July 2003 05:38 PM


New To Site? Need Help?

All times are GMT. The time now is 02:16 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