NAD 2600 speaker output relay replacement

[jamesmafyew]

Hi, I'm a longtime lurker, first time poster. I've searched the forums on this subject but haven't found what I need.

My old NAD 2600 has been having the typical problem of spotty sound on one or both channels at low volume. When the volume is turned up, the sound punches through. I've reflowed the solder joints throughout, and opened and cleaned the relays with DeoxIt and a brush. That cured the problem for about 5 months, but it's back now. Reapplied DeoxIt and a repeat cleaning isn't working anymore.

I can temporarily fix the problem by turning the amp off and turning it back on, so that the relays click off and back on. A day or two later, it will start having problems again.

I want to replace the relays, but don't know where to begin to source a part. The original part is listed as PXS-2405U, which is now unavailable. There doesn't seem to be a datasheet available for the part, and there are no markings on the relay itself to indicate its specs.

The service manual I'm working from is available here:
http://user.faktiskt.se/phon/misc/2600.pdf

I've attached an image of the relevant part of the circuit.

Can anyone help me find a substitute relay? Preferably a good sealed one, that won't be susceptible to these kinds of problems? I understand how relays work, but am not familiar with their parameters and how to choose some for this application.

I know there are repair places that work on these amps specifically and replace the relays, and I'm wondering what they're using. I'm not really willing to pay $150 to find out.

Thanks!

[h_a]

The link to the service manual is dead and there's also no attachement.

In fact you just need to know 2 things: supply voltage for the relay and necessary power rating. The former you can measure with a multimeter and for the latter you get the strongest part you can find that has the proper supply voltage, like the Omron G5Z part.

However, be sure to check pin-dimensions first.

Have fun, Hannes

[jamesmafyew]

Hi Hannes,

Thanks. The SM link was working yesterday, and I apparently lost the attachment in editing the post --- sorry.

Please correct me if I'm wrong: it looks like the supply voltage for the relay coil is 44V, from this picture.

And a new SM link:
http://www.anchorstates.net/nad2600sm.pdf

[megajocke]

faktiskt.se doesn't seem to allow hotlinking, try copying the link and pasting instead of clicking if it doesn't work.

It's two relays in series so each gets 22V, probably 24V relays.

I'm amzaed how similar (identical except the case and volume controls from a quick look) this amp is to the NAD2200, it looks like it's even the same boards

It looks like it uses the same relays (the circuit is identical) as the NAD2200 if it's of any help.

[jamesmafyew]

Yes, as far as I know, the 2200, 2400, 2600, and 2600A are all essentially the same amp --- same power supply, same boards, same protection, just slightly different chassis and front panel controls with some tiny tweaks. The difference is 99% marketing.

Are the relay part #s for the 2200 also listed as PXS-2405U?

The specs for the amp say it's capable of producing 50A of current but I'm assuming that that's ludicrous into an 8-ohm load, and that I'm looking at needing probably an absolute max of 20A rated contacts? I can't imagine that what's in there now is rated that high.

And from the looks of things, I won't be able to get something with similar pin spacing --- is it ok to use wires + heat shrink to connect new relays to the board?

[djk]

Be sure and adjust the value of R413 after changing the relays, the new ones are likely to have dfferent coil resistance.

[skifflemusic]

"Yes, as far as I know, the 2200, 2400, 2600, and 2600A are all essentially the same amp --- same power supply, same boards, same protection, just slightly different chassis and front panel controls with some tiny tweaks. The difference is 99% marketing".

Yes I did get a schematic for the 2600, I have one for the 2700, that is the amp that I own. I've listened to the 2400 and I believe the 2200 is the amp in the Nad 3300 which I own.

The sound of my 2700 is much different than the 2400, I was looking for a NAD that sounds like the 2700, thats why I was going to look at the schematics for the 2600 I've heard they are identical.

I see on Audiogon the NAD productions lists 92 and I believe the 2600 is 87' five years difference. I was looking at other amps 214, 208 etc. to see if the sound is the same. I prefer a wide soundstage that some people might consider thin or not warm, is all I can describe it. I also would say that the sound does not fill the space in between the speakers as much as most amps.

[stevenmaxva]

any luck with your NAD 2600?

I have a pair of them. one does not output at all. the other only outputs in stereo mode but not bridged mono. I would love to repair both of them. Luckily my 2200 is running great. I know nothing about electronics but would be willing to pay a small amount to have them fixed.

[BoboandRita]

My NAD 2600 was also punching thru at low volumes. I sent the unit to these folks. They upgraded the speaker relays and did a couple of modifications. The unit sounds better now than it did when it was new. Here's the info on the company.

http://www.angelfire.com/art2/stereorepair117/NAD.htm

[wizardofoz]

I have a 2200, and have had massive spikes out the left speaker when turning off the amp.

On removal of the left channel relay I found the contacts fused in the operated position - hence power off spikes in left channel

on opening up the top of the relay you might be able to burnish the contacts with some very fine wet n dry sandpaper.

My contact arm was actually deformed - by a short and heat too much for it, but managed to straighten it up with no problems and burnish up with the sandpaper and good as gold for now.

Will be looking for 2 replacement relays from farnell i am guessing and also looking to replace the horrendous binding posts with some decent banana plug types.

Hope this helps somebody out there...