NAD 502 230V conversion

[Ronj]

This has been a lucky week for me...

Just now I got another give away, well a trade in which is more or less a give away... Somebody traded in a truck load of partially faulty stuff and some cash in exchange to my pair of Wharfdale Diamond 8.3 Floorstanders.

Among them is a NAD 502, as per the original owner with a dead display. Also it's a 110V set and voltage here in Singapore is 230V.

Having replaced/modded display bulbs on many number of NAD-705s and like; I knew the mid 90 NADs display bulb is always the culprit! And I have the right medicine; pair of $0.5 high intensity white LEDs with 470Ohms each in series! As usual, when checked; the bulbs are powered by +/- 15V DC voltages.

Anyway while I was at it, I noticed that the power supply section is fairly simple and I should be able to replace it with a similar 230V transformer. And make my NAD 230V player. So I went online and downloaded the NAD502 Schematic!

Then wow! I am such a lucky bastard! Look what I have found on the power section. Let this part of Schematic, talk for itself...



Too good to be true... Is it real? Removing the Jumper J504 and soldering it back at J505... Is that all required? I can see polyprop or mylar C506 is 400V so it can take 230V AC. And no other connection from transformer to the main board; other than those 3 wire AC 12-0-12 lines.

Anyway I removed the AC lines from the rectifier section and going to change the jumper and measure the secondary voltage as a matter of precaution. Wish me luck guys!

[jitter]

Without the benefit of having seen the service manual, I would say it is indeed that simple.

For extra peace of mind, remove F501 and F502 first, then move jumper from J504 to J505 position, switch on and measure the voltages. Expect to measure a bit more than 12 Vrms as there's no load on the transformer without the fuses.

If everything seems OK you can put the fuses back.