Please help with NAD 1020 Pre-amp

[pureh2o]

Hi there. I need your help. I need to know the values of two electrolytic capacitors in my NAD 1020 Pre-amp. They are located on the board about 1 inch behind the treble pot. They are marked C533, and C531. Thank you for your help. John.

 

[lineup]

I do not know if this schema can help
http://www.diyaudio.com/forums/attachment.php?s=&postid=707896&stamp=1124659687

from this topic
http://www.diyaudio.com/forums/showthread.php?threadid=62671

this is what previous stuff can be found about NAD 1020
http://www.google.com/search?q=+site:diyaudio.com+"nad+1020"

 

[pureh2o]

Nad 1020 help

Thanks Lineup, but it does not give me the values. Thanks anyway for your help. John.

 

[Mooly]

Are they missing or something ? No markings on the originals ? Lineups link shows only one as an electrolytic, but I think I can make out some kind of text on there. C531 = 0.12 mfd ??? and C533 = 4?? could that be 0.47mfd or 4.7 mfd. You certainly won't harm anything if you get it wrong. 0.47 is a value that could be an electroylitic but it's small.

 

[lineup]

An externally hosted image should be here but it was not working when we last tested it.

this is the preamp section of NAD 3020 ( http://www.tcaas.btinternet.co.uk/index-4.htm )

There are two R531 and R533, but no capacitors with these numbers.
The values is in the lower channel. some values not easy to read.

 

[pureh2o]

Need Help With NAD 1020

Mooly, Lineup, The schematic you sent me Mooly is close to the 1020 but it ended with C528. It appears that the pre-amp section of the 3020 is not exactly the same as the 1020, but close. Lineup, Your schematic shows C531, and C533, but does not give values. Oh, these are Caps, not resistors. My grand daughter decided to grab these and play with them outside, and I can't find them. But thank you guys for your trouble, I really appreciate it. Maybe someone will have the schematic for the 1020. Again thanks, John.

 

[Mooly]

What about the ones in the other channel, or have they gone walkies

 

[zoranaudio]

Hello!
I made a NAD 1020b pre-amp clone long time ago, so I got pcb scans and all values of the components, but did not find the original 1020b schematic, but as I compared with other models of NAD integrated amps, the schematic is quite similar or equal in some parts.
So this is what I wrote for C:
C533=47microF/35V
C531=47microF/63V
This is from the original 1020b I made a clone and still listen on it.
I hope I will help you.
Regards,

 

[zoranaudio]

John!
I hope I helped you, cos this is taken from original NAD 1020b device.
If you find the original schematic I'll be happy.
I made this clone just with PCB,s scans and copying the values of all parts!
If you find schematic please e- mail me:
z37hwxzoki@yahoo.com
Best wishes from z37hwx HAM radio-amateur station
73 de ZOKI

 

[lineup]

So this is what I wrote for C:
C533=47microF/35V
C531=47microF/63V

Are these the same 47uF caps as C524, C523 in my posted schematic?

 

[zoranaudio]

Are these the same 47uF caps as C524, C523 in my posted schematic?

Well it's difficult to say without original schematic which I don't have too.
But, I think no, because if C533 and C531 was for the purpose and place where is signed red in your posted schematic than this caps should be the same voltage and for that purpose" for the feedback" usually is no more than 10 volts., and i wrote in my paper that c533 and c531 47 micro farads both but 35 & 63 volts so I am guessing that this caps are in other place , not the place you marked..
Unfortunately I loose the JPG images taken from the original NAD1020B, , what I found in my pc is just scanned PCB,s from this, and all components values is wrote on the paper by hand.
Perhaps I can open my cloned pre-amp to see what caps are 2 inches behind the treble potentiometer.
I opened so many times and i modified this pre-amp so now i maded "source Direct" option taken from other models of NAD which have this option, cos originaly 1020B does not have "source direct, or tone defeat" how you like it is the same.

Yepp!!!
in the meantime when uploading this image I found my old papers and found there that this C533, minus pole connected to anode of D505 and R550, so this caps is for the mute option perhaps and C531, but now this is not important.
Line up I also found the same purpose caps you red marked in this NAD1020B that caps are C525 &C526.

So now I hope everything is clear, and John again I hope I helped you, because the values of the caps I gave you is 100 % true.
But all will be more clear if we can find electrical schematic or complete servise manual, till now i didn't find , but have my papers with pcb and values of the components.
Good luck.

 

[pureh2o]

Nad 1020 Help

Grrreat! I really appreciate it guys. I can go forward now. 73s, and thanks again for all the help. John.

 

[zoranaudio]

Great dear John.
Now we can trust more cos both are HAM radio operators.
I wonder what's your call sign? we can made a QSO I am QRV mostly on 14MHz both CW ans SSB.
DIY spirit is 90 % in HAM radio operators, we know that very well as we see a lot of HAM's electronic designs.
GL & 73's de Z37HWX