NAD M22 Amplifier - Possible to upgrade Amplifier Boards to Newer Model?

[Sokel]

Certainly. Here they are. To me, it looks clean and I do not see any surface mount components on PSU unless they are populated bottom side of PCB.

What looks suspicious to me is the small trafo at the coils and relay board but it can just be its color.

It's certainly odd both modules to take a hit without PSU gets involved with it.

 

[boXem]

Just got response from Hypex and they no longer have replacement boards and ask repair person to find alternative solutions.

I just made some checks, NC400 and NC500 have the same pinout and gain, so an NC500 seems to be usable as drop in replacement to the NC400.
I have an old NC500 sleeping somewhere in the lab, if you are ready to pay for the shipment from Luxembourg to your place, it's yours. PM me if interested.

 

[RickS]

Am also sitting on some NC500 modules if shipping to US is better for you.

 

[Old_School_Brad]

Huge respect to @boXem and @Rick Sykora !

 

[decomo]

What looks suspicious to me is the small trafo at the coils and relay board but it can just be its color.

It's certainly odd both modules to take a hit without PSU gets involved with it.

Yes, PSU may be a culprit too since power amp boards have burnt components. Is there an easy way to find out if PSU is ok?
I have multimeter and Variac if they helps.

 

[RickS]

Yes, PSU may be a culprit too since power amp boards have burnt components. Is there an easy way to find out if PSU is ok?
I have multimeter and Variac if they helps.

Depends a little on how the amp interfaces between the amp module and the power supply. The SMPS may not power or power fully if amp modules report issues or is not present. The Hypex supplies usually have a relay that clicks slightly after power is applied and indicates full power. Otherwise, could be broken or in standby. Experience and/or a service manual help considerably.

The most basic check is for the rail voltages and they should be around 85 Vdc. It looks as though NAD used the standard J1 power connector and here are the pinouts per the Hypex spec (may not match NAD)...

 

[restorer-john]

This NAD M-22 amp is now sitting on my bench in Queensland, Australia.

Initial inspection suggests we have some upstream issues as both L+R modules have taken a hit in the same way. Some considerable collateral damage- smoked up SMD components and a dead amp. Also, the unit has taken a physical hit on the rear panel in the past, which the buyer (current owner) maybe didn't know about. More to come.

I may make a pictorial, depending on how it goes.

 

[GXAlan]

I was reading through the thread, flabbergasted at the disappointing service from NAD and HypeX, thinking about what @restorer-john has to say about the the reliability of these products, then loving the response from @boXem and @RickS and cheering on @restorer-john after hearing that it is in his hands.

If the analysis looks interesting, it’s definitely worth creating a pictorial and then we can tag the mods to try to get it promoted to the home page!

 

[restorer-john]

I was reading through the thread, flabbergasted at the disappointing service from NAD and HypeX, thinking about what @restorer-john has to say about the the reliability of these products, then loving the response from @boXem and @RickS and cheering on @restorer-john after hearing that it is in his hands.

At this point, I'm not going to make any statements as to what has actually caused the failure/s. It's a bit chicken and egg- which came first and why.

I'll upload some pictures soon.

 

[restorer-john]

Well gentlemen, we are all going to find out at the same time, whether the many hours spent on this NAD were wasted or not.

Today is the day.

Stay tuned.

 

[Doodski]

Well gentlemen, we are all going to find out at the same time whether the many hours spent on this NAD were wasted or not.

Today is the day.

Stay tuned.

Take it slow and take care!

 

[Old_School_Brad]

Take it slow and take care!

No, rush through it and make sure to film it for maximum entertainment.

 

[restorer-john]

Well, on the bright side, the power supply is up and running, the micro (3 PICs, two on the Hypex modules, one runs the whole amp) and all it main control is good, the front end, buffers, switchable XLR/RCA (a very cool tiny solenoid operated latching selector which had a faulty drive circuit) all good now.

A lot of SMD microsurgery, but the Hypex amp modules are not working. All rails are good, all local regulators are good and we have differential buffered signal right up to the modules.

We have a low level sawtooth that can be 'sort' of modulated and a virtually silent (just noise) other module. The micro 'knows' the modules are sending a clip/ocp, but we aren't as bad as power supplies being shutdown.

I'll be talking with @decomo to see where he want to go from here. I'm not sure whether I'd be throwing much more money at it, a pair of modules would run about $400 and then there's a lot more labour (it takes forever with this NAD design as they have a million spacers, washers, etc. They don't use the Hypex 'heat spreader' at all, so device tolerances may be different. Maybe, maybe not.

The previous repairer had attacked the unit, mixed up machine and self tappers, threaded holes got damaged and even some random screws got used where they'd clearly lost a few. But I can't totally blame the repairer as I believe this amp has seen at least two potential 'techs' before me.

And I'll post a bunch of pictures (I took heaps), even though it's not as exciting as I'd hoped.

 

[Scrivs]

Any update? I'm waiting with baited breath. Just had my second NC252MP shit the bed within 6 months of the first. One module was built in 2019, the other. 2020. Both very lightly used, with adequate cooling, always disconnect from mains (via IEC switch) when not in use
It seems like the stby ps is coming on (1st relay click), and never makes it past there (no second click/output relay sound.

Identical failure mode for both. It looks like a mechanical design whoopsie, with the PCB having significantly warped due to the way the metal baseplate (heatsink) attaches to it. Poorly thought out, not designed with longevity in mind.

My newest Icepower board is 5 years old, the oldest about 12. I've got two 200ASC, four ASX50SE's that I converted into BTLs, and a 125ASX2.
Icepower failure rate? ZERO.

 

[decomo]

Any update? I'm waiting with baited breath. Just had my second NC252MP shit the bed within 6 months of the first. One module was built in 2019, the other. 2020. Both very lightly used, with adequate cooling, always disconnect from mains (via IEC switch) when not in use
It seems like the stby ps is coming on (1st relay click), and never makes it past there (no second click/output relay sound.

Identical failure mode for both. It looks like a mechanical design whoopsie, with the PCB having significantly warped due to the way the metal baseplate (heatsink) attaches to it. Poorly thought out, not designed with longevity in mind.

My newest Icepower board is 5 years old, the oldest about 12. I've got two 200ASC, four ASX50SE's that I converted into BTLs, and a 125ASX2.
Icepower failure rate? ZERO.

Great to know. Thanks. I might look out for a good quality Icepower based amp in the future if I am looking for an amplifier near future.