NAD 1020 Preamp Problems

[gmilitano]

Originally posted by adyf
hi... any news on your 1020? did you have any good results from your upgrades?

I have a 1020 too I'm interested in upgrading...

adrian

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.

[adyf]

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

[gmilitano]

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.

Originally posted by adyf

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

[commsysman]

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.

[anatech]

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