chicco_36 said:
I was only considering bypassing caps on the power supply. My limited experience has shown some positive results with this.
It is interesting you mention that bypassing caps in the signal path provides poor results. I have read that in the past, but it did not make sence to me. On a speaker crossover, bypassing electrolytics provides large improvements and is common practice. Why is this not the case in a preamp signal path? In both cases, the signal is AC, so what is the difference between the two?
resolder all RCA jacks
I found that my NAD 1020A needed resoldering of many if not all of the RCA jacks. The wiggling they undergo even broke the copper traces free from the PCBs. I laid braided wire over the traces to reinforce them (soldered of course). I have a crosstalk problem in my 1020A. If any other sources (like Tuner) are turned on I hear them faintly in the background. Why is this? Thanks.
Greg
I found that my NAD 1020A needed resoldering of many if not all of the RCA jacks. The wiggling they undergo even broke the copper traces free from the PCBs. I laid braided wire over the traces to reinforce them (soldered of course). I have a crosstalk problem in my 1020A. If any other sources (like Tuner) are turned on I hear them faintly in the background. Why is this? Thanks.
Greg
Re: resolder all RCA jacks
I recently read about the same problem with the RCA jacks. I will give mine a closer look, but I have not had problems with the sound quality. Another option would be to replace the jacks and hardwire them.
I found a link where some mods were made to the preamp section of a 3020.
http://gnu.295.ca/peak/audio.html#2.2
Upgrading C517/C518 is obvious and I plan to do that. Note that it is reccomended to bypass these with a 0.1uF film.
The mod I find interesting is removing C506, C508 and R514 and replacing with a 0.1uF film. Seems simple enough to try.
BTW - Do you have a schematic for the 1020 that you would be willing to share?
GringoAudio said:
I recently read about the same problem with the RCA jacks. I will give mine a closer look, but I have not had problems with the sound quality. Another option would be to replace the jacks and hardwire them.
I found a link where some mods were made to the preamp section of a 3020.
http://gnu.295.ca/peak/audio.html#2.2
Upgrading C517/C518 is obvious and I plan to do that. Note that it is reccomended to bypass these with a 0.1uF film.
The mod I find interesting is removing C506, C508 and R514 and replacing with a 0.1uF film. Seems simple enough to try.
BTW - Do you have a schematic for the 1020 that you would be willing to share?
Hi GG,
There’s a lot of info on the net about paraleling caps, pros and cons. I use to read a lot in the past, and like always there are diferent opinions on this subject. I’m moding a lot of audio equipment and in my expirience, paraleling elcos with bipolars in the signal path (mostly in DC blocking input-output positions) results are unsatisfectory for me at least. The sound becomes defocuset, strange, a step back from apsolute neutrality. I did’t have any measurments or grat knolige to proof what realy happening with the sound. However, I trust my ears.
About PSU bypasing, I ollways do that, clean power supply is a must for good sound.
I also like to point that today modern audio electrolitic capacitors are far better than 20 or 30 years ago.
There’s a lot of info on the net about paraleling caps, pros and cons. I use to read a lot in the past, and like always there are diferent opinions on this subject. I’m moding a lot of audio equipment and in my expirience, paraleling elcos with bipolars in the signal path (mostly in DC blocking input-output positions) results are unsatisfectory for me at least. The sound becomes defocuset, strange, a step back from apsolute neutrality. I did’t have any measurments or grat knolige to proof what realy happening with the sound. However, I trust my ears.
About PSU bypasing, I ollways do that, clean power supply is a must for good sound.
I also like to point that today modern audio electrolitic capacitors are far better than 20 or 30 years ago.
Now, strangely enough, the supply caps after the regulator are in the signal path. Note I suggested a trial as most opinions are different or follow trends.
GG, relax and have some fun. Panasonics should be fine. Having a look at the jacks is a good idea. More than one brand have a problem with this. A child will tell you what they like for sure if you want the truth about bypassing caps. I am not giving an opinion here at all.
-Chris
GG, relax and have some fun. Panasonics should be fine. Having a look at the jacks is a good idea. More than one brand have a problem with this. A child will tell you what they like for sure if you want the truth about bypassing caps. I am not giving an opinion here at all.
-Chris
Hi GG,
Electrolytics can last over 20 yrs, or less than 2 yrs. It depends on how hot they run, and the level of ripple current through them. The quality of the capacitor matters as well. There have been defective runs of caps before.
If you are looking to get the best quality, consider replacing the electrolytic capacitors. If you have 1 uF coupling caps, replace them with film caps at this time.
-Chris
Electrolytics can last over 20 yrs, or less than 2 yrs. It depends on how hot they run, and the level of ripple current through them. The quality of the capacitor matters as well. There have been defective runs of caps before.
If you are looking to get the best quality, consider replacing the electrolytic capacitors. If you have 1 uF coupling caps, replace them with film caps at this time.
-Chris
adyf said:
Hi, I have not changed any of the capacitors yet as I really need to make a list of what is needed and place an order. Plus, the lack of a schemtic is also holding me back. The pots also need cleaning and I should consider dropping in muting transistors to replaced the dead ones that I had to pull. I am using it as my preamp right now and it works good. The pot is scratchy and there are pops when you power up or switch sources. In reality, there is a lot that can be done to this old unit. Recapping all the electrolytics and adding a condictive plastic pot could be expensive. For the time being it is working and I have other projects on the go, so it will likely sit a while longer. I will post updates if I make changes.
BTW - do you have a manual/schematic for the 1020?
Cheers,
Gio.
hi...
yes. i have a 1020 that i'm planning on using as a preamp to my upgraded Quad 405-2 power amp..
at the moment i'm using a nad 3120 as a pre but was interested in the upgrade possibilities of the 1020 so i could use my 3120 somewhere else...
i have the schematic for the 3120, which is the stripped down version of the 3020.. has pretty much the same preamp section as the 3020 and 1020. It's not exactly the same though, as it doesn't have the MM capacitance switch or tone controls.. i can email it too you.. attachment size is too limited on this server!
Don't know if you've noticed but a UK company called fidele audio does upgrades to the original 3020 which these are all similar too and has quite specific details about these.. might be worth looking at.. here's the link http://www.fidele.co.uk/3020_details.htm
yes. i have a 1020 that i'm planning on using as a preamp to my upgraded Quad 405-2 power amp..
at the moment i'm using a nad 3120 as a pre but was interested in the upgrade possibilities of the 1020 so i could use my 3120 somewhere else...
i have the schematic for the 3120, which is the stripped down version of the 3020.. has pretty much the same preamp section as the 3020 and 1020. It's not exactly the same though, as it doesn't have the MM capacitance switch or tone controls.. i can email it too you.. attachment size is too limited on this server!
Don't know if you've noticed but a UK company called fidele audio does upgrades to the original 3020 which these are all similar too and has quite specific details about these.. might be worth looking at.. here's the link http://www.fidele.co.uk/3020_details.htm
HI,
I have the 3020 schematic and the preamp section is pretty much the same. There are some differences, but I think that is because mine is a 1020B.
The capacitor upgrades are fairly obvious. For the pre-amp, I don't think beefing up the PSU will help much. What do they charge to do that service to the 3020? That is a lot of work to replace all of those caps.
Cheers,
Gio.
I have the 3020 schematic and the preamp section is pretty much the same. There are some differences, but I think that is because mine is a 1020B.
The capacitor upgrades are fairly obvious. For the pre-amp, I don't think beefing up the PSU will help much. What do they charge to do that service to the 3020? That is a lot of work to replace all of those caps.
Cheers,
Gio.
adyf said:
NAD 1020 and 3020
I have owned both the 1020 and 3020 and the problem you described is very common and has strange symptoms, and an
even stranger cause. I originally suspected a bad power supply diode, because you can see the garbage in the DC power suppy output on a scope.
The power switch on these things gets a high resistance condition in the contacts that causes wierd things, including what you describe (frying noises in the audio, or sputtering). The switch is very marginally rated, and the solution I found was to replace it with a new 1.5 amp switch but then use that only to supply coil current to a relay with 10 amp contacts which actually turns on the power to the transformer. I glued a relay with a plastic case upside down between the switch and transformer on the circuit board using epoxy. I did this on two 1020s and one 3020 with good results. Just get a multi-purpose relay with 120v (or 240v) coil and 10A rated contacts.
I have owned both the 1020 and 3020 and the problem you described is very common and has strange symptoms, and an
even stranger cause. I originally suspected a bad power supply diode, because you can see the garbage in the DC power suppy output on a scope.
The power switch on these things gets a high resistance condition in the contacts that causes wierd things, including what you describe (frying noises in the audio, or sputtering). The switch is very marginally rated, and the solution I found was to replace it with a new 1.5 amp switch but then use that only to supply coil current to a relay with 10 amp contacts which actually turns on the power to the transformer. I glued a relay with a plastic case upside down between the switch and transformer on the circuit board using epoxy. I did this on two 1020s and one 3020 with good results. Just get a multi-purpose relay with 120v (or 240v) coil and 10A rated contacts.
Hi commsysman,
Crydom makes SS relays that might be easier to use. More $$.
But since you have a relay in there, why not go all the way and put the contacts across a power resistor (2R2 ~ 10R) and create a soft start circuit. The old power switch ultimately carries the current, but there is a reduced surge current. This has far more advantages.
You are almost there.
-Chris
Crydom makes SS relays that might be easier to use. More $$.
But since you have a relay in there, why not go all the way and put the contacts across a power resistor (2R2 ~ 10R) and create a soft start circuit. The old power switch ultimately carries the current, but there is a reduced surge current. This has far more advantages.
You are almost there.
-Chris
My problem was with a 3020A, which has the same preamp as the 1020 (A&B). Is your preamp actually a 1020, 1020A, or 1020B?
In any event, the FET J111 (Q509, 510) has a 10MegOhm resistor on the gate pin, 470 Ohm on the source pin, and 39K Ohm on the drain pin. Run a jumper from the 470 Ohm resistor to the 39K Ohm resistor and the JFET has been bypassed.
In my case on the 3020A, the capacitor powering the JFET's gate pin had 80VDC on it but was only a 63VDC cap. The result was predictable. I replaced it with a 100VDC cap and the mute circuit has worked properly since.
Anyway, that's what worked for me on a 3020A preamp - as you can see no one ever answered my inquiry.
Just make a habit of turning the volume all the way down before turning on the preamp or switching input signal sources, lest you damage your amp or speakers (most likely). Or your ears if you use earphones.
Glad you got it working.
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