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NAD 3020 Rebuild and Upgrade

Copying and pasting into an online translator doesn't really help, I could have done that (and I did). I/we need to know what your problems are, and what you are trying to do. It sounded like something was running too hot after replacing some transistors. The recommended suggestions are in my thread above, unless there is a problem sourcing the BD139/140 combo, then use those. If you have a bad output transistor, you'll need to replace that too.

Like I said, we need to know clearly what your problems are before we can help.

Lee.
 
Hi Lee,
Your original post going back to 2012 is a great read and learning experience.
There was a comment that ceramic caps should not be replaced with films.
In your 3020 rebuild, were most of the ceremics replaced with film? If so, what was the impact on the sound?
Thanks and keep the posts coming.
Robert.
 
Soundphile said:
Hi Lee,
Your original post going back to 2012 is a great read and learning experience.
There was a comment that ceramic caps should not be replaced with films.
In your 3020 rebuild, were most of the ceremics replaced with film? If so, what was the impact on the sound?
Thanks and keep the posts coming.
Robert.
Click to expand...

Hi Robert,

I never changed out the ceramic caps, I also left in the green Mylar film caps. When I did the 1020 into 3020 project, I used almost entirely WIMA brand films to replace the green mylars, and TDK stacked ceramic capacitors to replace the ceramic disc type. The TDK ones had a much tighter tolerance than the disc type. That one sounded really good!

I'm currently running a 3120 which is a 3020 without tone controls. I completely redid the power amp stage with metal film resistors, WIMA and TDK caps, and all new transistors except for the outputs.

Hope this helps,

Lee.
 
Hey Lee Sonic!

Just want to say you inspired me to recap my old NAD 3020 also, I'm just about done with replace the capacitors and it sounds great. I have a question, though I'm a newbie to the electronic work. Do i have to replace the resistors also? have you made any changes with the capasitors that demands any resistor to be changed? and does it make any difference to the sound?

thanks once again for inspiring me, its such a good amplifier!:thmbsp::smoke:
 
leesonic said:
2SD669 replace with BD139
2SB649 replace with BD140

But for the drivers, you might want to use :

2SD669 replace with BD237
2SB649 replace with BD238

Lee.
Click to expand...

I'm rebuilding a Proton D940 which also uses the 2SB649C/D and 2SD669C/D as drivers which I might replace, but another thread listed a very different substitute for them. Depending on the specs you need, the BD's might not be the best substitutes. Here's some of the key specs of each:

2SB649A (2SD669A)
Vcb - 180
Vce - 160
Veb - 5
Ic - 1.5A
Pw - 20W
hfe - 100-320 (for C/D variants)
ft - 140MHz (typical)

BD140 (BD139)
Vcb - 80
Vce - 80
Veb - 5
Ic - 1.5A
Pw - 12.5W
hfe - 100-250 (for the 16 version)
ft - ???

BD238 (BD237)
Vcb - 100
Vce - 80
Veb - 5
Ic - 2A
Pw - 25W
hfe - 25 - ???
ft - 3MHz

KSA1220AY (KSC2690AY)
Vcb - 160
Vce - 160
Veb - 5
Ic - 1.2A
Pw - 20W
hfe - 160-320 (for the 16 version)
ft - 175MHz (typical)
 
thenomadsoul said:
Just want to say you inspired me to recap my old NAD 3020 also, I'm just about done with replace the capacitors and it sounds great. I have a question, though I'm a newbie to the electronic work. Do i have to replace the resistors also? have you made any changes with the capasitors that demands any resistor to be changed? and does it make any difference to the sound?
Click to expand...

If you change ALL the resistors to 1% metal film, it improves the sound. It's a lot of work though, and not as big an improvement as replacing the capacitors with new ones and upgrading to films where possible.

What I usually do is replace the two dropper resistors in the power supply with 3 watt metal film. These should either be 10 and 27 ohm, or 10 and 100 ohm depending on what model you have. I also replace the dropper resistor for the power meter with a 5w one, these are 680 ohm. It won't make anything run any cooler, they will still dissipate the same amount of heat, just now they will be running a little less close to the edge.

jheu02 said:
I'm rebuilding a Proton D940 which also uses the 2SB649C/D and 2SD669C/D as drivers which I might replace, but another thread listed a very different substitute for them. Depending on the specs you need, the BD's might not be the best substitutes.
Click to expand...

That's very interesting, I'll certainly bear it in mind for any further restorations. I doubt if the old 3020 needs all that bandwidth, it's not a "fast" amplifier like some of the older Pioneer non-switching amps. Thanks for posting.

Lee.
 
Last edited:
I was mainly looking at the voltage the BDs could handle. Not sure what the NAD rails are running at, but may not be much leeway there. When subbing, I go for as many close matches as possible to the original Q. Here is the thread I was referencing for the KSA/KSC combo which got me looking at the datasheets.
 
leesonic said:
If you change ALL the resistors to 1% metal film, it improves the sound. It's a lot of work though, and not as big an improvement as replacing the capacitors with new ones and upgrading to films where possible.

What I usually do is replace the two dropper resistors in the power supply with 3 watt metal film. These should either be 10 and 27 ohm, or 10 and 100 ohm depending on what model you have. I also replace the dropper resistor with a 5w one, these are 680 ohm. It won't make anything run any cooler, they will still dissipate the same amount of heat, just now they will be running a little less close to the edge.

Lee.
Click to expand...

Okay, then i should order those also. I´ve got the same model as you. I used your excelfile for the order, except the resistors.

Just to make clear, its the C816,C903 and C904 you´ve upgraded?
thanks for your help and knowledge!
 
jheu02 said:
I was mainly looking at the voltage the BDs could handle. Not sure what the NAD rails are running at, but may not be much leeway there.
Click to expand...

Only 28-30v. It's only a 20w amplifier after all.

I wonder what the specs are of the original 2N6551/2N6554 and 2N6553/2N6556 combos used as driver transistors in the original/later versions? If I ever come across an amp I can't fix, or more likely a 7020 receiver that's beyond economical repair, I pull, test and keep all the working power transistors.

It's funny. People talk about these 3020s and say they were poorly made. While that might be true, they used some decent components in them. The output transistors are usually RCA or Motorola. The drivers are usually Motorola for the 2N versions, and Hitachi for the 2SB/2SD versions. The small signal transistors often have PH on the top, which I think means Phillips. The capacitors, well the earlier versions had a three pointed star, so would these have been Mitsubishi? Not sure how these compare to Nichicon, Panasonic or Elna.

Someone is going to yell "counterfeit!", but remember this was back in the late 1970s/early 1980s. Counterfeit transistors weren't around then, just like counterfeit golf clubs or Land Rovers.

thenomadsoul said:
Just to make clear, its the C816,C903 and C904 you´ve upgraded?
thanks for your help and knowledge!
Click to expand...

Huh? Not sure what these part numbers refer to?

Lee.
 
Yes, the three pointed star (triangle) is the Matsushita (Panasonic) symbol. The only issue i have with their caps are with the ones in the lavender colored sleeves. I've found some of those open and causing problems in some amps. Their blue sleeved ones I've found generally close to spec, though in the Proton I'm redoing, I did find several heat stressed ones out of spec. Interestingly, the one in my pics with the very shrunk sleeve tested fine at the low voltage of my DMM. There were others that the sleeves were turning greyish black that were oout of 20% tolerance. Modern FM, FC, FR, TS-HA series are great caps in my book.
 
Lee,
my name is chris and i am impressed. i know NOTHING about electronics at all, but i am very interested in learning. where might i get a list of all the tools i need, (meters included), that i would need for rebuilding the NAD3020s? and where would you recommend purchasing all the parts you listed in your rebuild?

one final question and i will not bother you any longer... how did your 3020 sound after all your tweeking? i am hooking up my newly acquired 3020 and my 2200 to a set of KEF Q70's and i am anxious to hear what it sounds like. hope to hear from you.

thanks in advance
chris
 
I replaced main filter capacitors with Nichicon BT series capacitors (long life 10000h, 125°C) and I feel significant improvement in bass.
 
c smith said:
Lee,
my name is chris and i am impressed. i know NOTHING about electronics at all, but i am very interested in learning. where might i get a list of all the tools i need, (meters included), that i would need for rebuilding the NAD3020s? and where would you recommend purchasing all the parts you listed in your rebuild?

one final question and i will not bother you any longer... how did your 3020 sound after all your tweeking? i am hooking up my newly acquired 3020 and my 2200 to a set of KEF Q70's and i am anxious to hear what it sounds like. hope to hear from you.

thanks in advance
chris
Click to expand...

Hey Chris,

Thank you for your compliments. All you need to fix one of these amplifiers is :

A decent soldering iron.
A solder sucker and/or desoldering braid.
A basic multimeter.
A transistor tester or one of those universal testing things (search eBay for MK-168).

You can get the components from mouser electronics.

As for the sound, they sound amazing.

Lee.
 
I am trying to recap my NAD3020, and my choices of caps (both electrolytic and film) are a bit limited - Any alternatives for the Nichicon KL series for the low leakage caps in the input side ?
 
Hi, I just joined this forum to read up on recapping a NAD 3020 and found this post. The problem is that most images that he has posted are now not showing. Is there any way that these images can be reinstated? I don't find these posts much use without them (a comment which is bound to cause some to make not very flattering comments).
 
Thanks for that. There are more images showing on that thread but 2 are not showing. I posted about that on that thread.
 
Great to see thead still alive, these are great amps and are going up in value.
I have 2 3020`s and 1 4020a tuner and another amp the 2240pe.
Also a Realistic sta-95 what a beautifull reciever
Plus good old Marantz 2230.
Running through Large Advents
I have recaped all of these and love them all. :beerchug:
 
Hello everyone. I dig up this thread. I am new to the forum and I do not speak English ... so I use a translator. sorry for the rough syntax. I read this forum for a long time.
it's been a long time since I want to restore my nad 3020 but it's an "i". I bought it new in ... I do not know anymore. I decide now.
at first I would like to change the electrochemical capacitors.
- I was thinking of keeping all the values except the 4700μf 35v capacitors that I thought would go up to 6800μF 50 or 63v or more. the diodes are 1N5401, it accepts 3A so I did not think to change them.
What do you think about this ? should I change the values or voltages of other capacitors?
I am waiting for your comments. Thanks for the help, dom2
 
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