Hypex Ncore

[Simtu]

HELP! HELP!

There has been much talk lately about the heat produced by the SMPS600 module. My amplifiers are kept inside a closed cabinet so I have been concerned about safety/long term reliability. With this in mind I have just fitted heatsinks down the sides of my modu2000 aluminium enclosure. As these were too long, I have machined them down to length and used the offcuts as heatsinks for the smps. I have bonded them in place with thermally conductive glue.

Both amps were working perfectly prior to this mod, and have been working glitch free for several weeks. Following the mod, one of the amps will no longer power up. The relay no longer switches over after the initial 2 or 3 second pause. The other amp works perfectly.

Both amps are identical - same wire lengths, positions etc.

None of the heatsinks contacts any of the case work but I can now measure 120v on anything connected to ground (my incoming mains is 240v). I have been over everything for hours with a magnifying glass, thinking I must have caused a short somewhere but I can find nothing. I have checked every single connection but I cant find anything wrong.

I am not an electronics whizz but I did build up these units with great care and attention. I am hoping that someone can point me in the right direction. With the case work now live, I am concerened that I will have fried the ncore too. I have emailed Hypex too but have not yet received a reply.

 

[Abraxas336]

@slowlearner:

Re "ground connected to IEC" - just to make sure there is no misunderstanding: if you are using a simple metal case you are required to connect the safty earth from your IEC to the metal case for saftey reasons.

Regards
Sven

 

[Ianmac]

I cant see anything from your photo but I would not have modified any board in any way due to possible warranty issues. Good luck with your search.
I have not found any heat issues with my amps they run cooler than my UcD's.
Your case has vent slots in the base and an adequate area to sink any heat from the NCore, I assume you used heat sink compound and you have some rubber feet on the bottom to let air in. Do you have slots or spacers between top and sides to let air out?

 

[pdb]

Re: HELP! HELP!

...None of the heatsinks contacts any of the case work but I can now measure 120v on anything connected to ground (my incoming mains is 240v)...

How much distance between the bottom of the SMPS600 and the case do you have? Should be 6mm or insulated if less.

A live chassis is not fun. Take care.

Per

 

[ChrisPa]

@slowlearner:

Re "ground connected to IEC" - just to make sure there is no misunderstanding: if you are using a simple metal case you are required to connect the safty earth from your IEC to the metal case for saftey reasons.

Regards
Sven

As I understand it, that's not the case with 'class 2' products, and the smps 600 is designed as class 2

Look at the data sheets and recommended wiring.
Ie. the data sheets recommend you don't have a mains earth

 

[pieter t]

There has been much talk lately about the heat produced by the SMPS600 module. My amplifiers are kept inside a closed cabinet so I have been concerned about safety/long term reliability. With this in mind I have just fitted heatsinks down the sides of my modu2000 aluminium enclosure. As these were too long, I have machined them down to length and used the offcuts as heatsinks for the smps. I have bonded them in place with thermally conductive glue.

Both amps were working perfectly prior to this mod, and have been working glitch free for several weeks. Following the mod, one of the amps will no longer power up. The relay no longer switches over after the initial 2 or 3 second pause. The other amp works perfectly.

Both amps are identical - same wire lengths, positions etc.

None of the heatsinks contacts any of the case work but I can now measure 120v on anything connected to ground (my incoming mains is 240v). I have been over everything for hours with a magnifying glass, thinking I must have caused a short somewhere but I can find nothing. I have checked every single connection but I cant find anything wrong.

I am not an electronics whizz but I did build up these units with great care and attention. I am hoping that someone can point me in the right direction. With the case work now live, I am concerened that I will have fried the ncore too. I have emailed Hypex too but have not yet received a reply.

Simtu,

The SMPS600 is mounted on stand-offs, and it's hot parts do not make contact with the chassis, so the extra heatsinks are of very little value to remove the heat of the power supply.
The original case should be sufficient to dissipate the heat of the Ncore module.
As your amplifier is in a closed cabinet you should improve air flow.
As Ian suggested make some openings in the ground plate to improve convection.
A slow (and inaudible as it's inside the cabinet)) fan might be a better approach to get rid off excessive heat.

Good luck with solving the electrical problem.

 

[Julf]

None of the heatsinks contacts any of the case work but I can now measure 120v on anything connected to ground (my incoming mains is 240v).

What are you using as a reference point for your measurement?

You say you measure 120 V between ground and ... what?

It also looks like your cooling fin comes quite close to the fourth corner mounting spacer, where it seems you have connected a couple of ground leads. Are you sure there are no wire strands touching the cooling plate?

 

[Abraxas336]

As I understand it, that's not the case with 'class 2' products, and the smps 600 is designed as class 2

Look at the data sheets and recommended wiring.
Ie. the data sheets recommend you don't have a mains earth

Chris, I know the data sheet - it says not connecting saftey earth is ok if class II construction is used. That term refers to the way of constructing the case, not the unit. It means that there is an additional insulation between dangerous voltages and metal case. Which is not the case if you just mount the SMPS on a metal floor.

Regards
Sven

Edit: more info here.

 

[Julf]

It means that there is a insulation between dangoerous voltages and metal case. Which is not the case if you just mount the SMPS on a metal floor

If you enclose the SMPS in a case, and the SMPS is mounted using the supplied spacers, the dangerous voltages are isolated from the case. Note how the fourth, conductive, spacer is outside the red area in picture at the bottom of page 3 of the data sheet.

 

[Abraxas336]

Of course it is insulated, otherwise you'd get shocked everytime you touch it.

However - as far as I know it is not sufficient to have 10 mm clearing between metal case and hazardous voltage to meet class II requirements. That's class I. Might be wrong, though. Bruno will certainly comment.

Regards
Sven

 

[pieter t]

However - as far as I know it is not sufficient to have 10 mm clearing between metal case and hazardous voltage to meet class II requirements. That's class I. Might be wrong, though. Bruno will certainly comment.

Regards
Sven

Checking class I and II requirements I don't find anything on distance clearing.
Class I: safety by connection to earth (ground);
Class II: no connection to earth (ground) but double insulation of voltage carrying parts.
The datasheet of the SMPS600 is very clear: use the 10 mm spacers to get at least 6 mm clearance; when using shorter spacers (having the power supply fitted in a 1U enclosure) apply an additional layer of insulation between SMPS600 and chassis .
What's the problem??

 

[Abraxas336]

Pieter,

There is no problem. Again, as far as I know:

In order to build something with a metal case that is not immediatly deadly you need an insulation. That - for instance - can be >=6mm clearing. If you're getting below 6mm you need additional insulation. However, it's still class I and you need to connect saftey earth.

If you want to build something with a metal case that meets class II (thus, doesn't need saftey earth) you need a double insulation. E.g. a seamless plastic housing around your metal housing. This is normally used for handheld tools like hair dryers etc..

A good example for why this is so is Simtu. What he is measuring could be deadly. His picture looks like he has no saftey earth connected. It is not unusual that there is some potential between ground/earth, if there really was a significant current flowing the earth leakage circuit breaker would tell him.

Regards
Sven

 

[pieter t]

Pieter,

There is no problem. Again, as far as I know:

In order to build something with a metal case that is not immediatly deadly you need an insulation. That - for instance - can be >=6mm clearing. If you're getting below 6mm you need additional insulation. However, it's still class I and you need to connect saftey earth.

If you want to build something with a metal case that meets class II (thus, doesn't need saftey earth) you need a double insulation. E.g. a seamless plastic housing around your metal housing. This is normally used for handheld tools like hair dryers etc..

A good example for why this is so is Simtu. What he is measuring could be deadly. His picture looks like he has no saftey earth connected. It is not unusual that there is some potential between ground/earth, if there really was a significant current flowing the earth leakage circuit breaker would tell him.

Regards
Sven

Sven,

I have quite some electronics in the house which are housed in metal cases, and which meet class II, with 2-pole power cords (unearthed). Obviously the inside electronics should meet class II requirements.
IMO the NC400/SMPS600 combo can perfectly be built into a metal enclosure following class II without earthed power cords, so connecting the amplifier to an unearthed mains outlet (which will actually very often be the case in practice also with the class I built...).
When someone does not trust his abilities in this regard it is quite logical to build class I with appropriate earthing, but it is not a necessity.
In Hypex datasheets I see no indication to do so.
Also take a look at Hypex' application note on earthing/insulation.

 

[DavidT]

Here are some measurements taken from my quad amp chassis, employing dual UCD 400 for bass, and dual NC 400 for the higher ranges. Cooling holes on lower chassis, open top, user heat sinks for amps. One SMPS per amp pair (total of two SMPS)

Instrument: FLUKE 179 True RMS VM, using Type K thermocouple (TC)

Calibration: Boiling H2O @ 102 C ( 2 C correction required ), room air @ 21.5 C

Method: Amp at idle for 1 hr. Finger press TC bead against surface using a 0.5 mm thick coated fiberglass protective cloth until temp reading stabilizes. Record non-corrected data.

UCD 400

Output inductor: 46.0 C

Main electro-cap: 42.1 C

Blue T-Bar: 42.1 C

User heatsink: 37.7 C

non HS TO-220 devices: 71 C ( too hot to touch)


NC 400

Output inductor: 46.5 C

Electro caps: 38.2 C to 52.7 C ( too hot to touch)

User heat sink: 34.3 C


SMPS 600

Main xfmer: 47.7 C

Small HS: 36.0 C

Large HS original: 46.5 C

Large HS w/ user CPU style HS added: 38.2 C


Note: temps will be higher with the vented top installed...

**********************************************************

BTW, all 4 amps output ~ 190 WRMS into 8 ohms, both channels driven, just before clipping, with 120 VAC line voltage

That is: 190W * 4 = 0.760 KW! Yowzer!

Regards, DavidT

 

[Simtu]

Simtu,

The SMPS600 is mounted on stand-offs, and it's hot parts do not make contact with the chassis, so the extra heatsinks are of very little value to remove the heat of the power supply.
The original case should be sufficient to dissipate the heat of the Ncore module.
As your amplifier is in a closed cabinet you should improve air flow.
As Ian suggested make some openings in the ground plate to improve convection.
A slow (and inaudible as it's inside the cabinet)) fan might be a better approach to get rid off excessive heat.

Good luck with solving the electrical problem.

I added the additional heatsinks in order to increase thermal mass and total surface area, in order to dissipate heat at a greater rate. Once this heat has radiated into the air within the enclosure, the additional heatsinks that I have added to the enclosure will again assist in dissipating the heat to the outside. This system of heat transfer may be relatively inefficient but it must surely help to improve the cooling. I will also be asking Modu2000 for a quote to produce some custom enclosure panels with additional ventilation slots though. The various merits of adding extra heatsinks was discussed earlier in this thread and it seemed a good idea. Beginning to wish I hadn't bothered. Ah the benefits of hindsight.......

This afternoon, I swapped the two SMPS's around without changing anything else, and hey presto the other amplifier works again. The problem must be somewhere on the smps board although I can see nothing visual to suggest a short - the problem must presumably come down to a component failure. The question is why would this occur at the same time that I glued a couple of heatsinks in place? Can anybody hazard a guess where the fault may lie? To reiterate, I have been over the entire circuit board and there is no foreign matter anywhere and nor is there any obvious sign of discolouration/burning etc. Would the failure of any particular component result in a short to ground (presumably via the conducting corner stand off)?

I would love to avoid the expense and hassle of returning the faulty SMPS to Hypex so would welcome any and all further advice. Thanks in advance

 

[Ianmac]

If the amp is now working after you have swapped SMPS boards it could be that your problem is associated with the interconnect cable.

Check the suspect amp interconnect at the SMPS end and ensure all the pins are fully home into the plastic connector. The pins are crimped onto the cable and unlikely to be problematic. After wiring, the pins themselves are inserted into the plastic connector and held in position by two small metal wings in the pin mating with shelves in the connector. If the pins are accidentally twisted through 90 deg this holding arrangement can fail leaving the pin loose in the connector and not mating correctly with the associated socket on the SMPS plug.
I found this when making my own interconnect cable

Try moving the cable and see if you can replicate the fault

 

[firemanbrandon]

Hello Group! I am new here, but have been watching this thread for quite some time. I have finally ordered 2 NC400 and 2 SMPS and await the email that they have shipped! As I wait, I have been shopping for enclosures and the other components needed to put these amps together. My questions are as follows: Are there any disadvantages to putting two of these amps in one enclosure like siliconrays RE4307. Would it be better to get 2 RE2207's? I am new to the DIY audio world so I also need a little direction in picking out the best affordable XLR inputs, binding posts, and IEC sockets. I apologize in advance if this topic has already been touched on, but I have spent hours reading and haven't found a good answer!

Thanks in advance,
Brandon

 

[Julf]

I have finally ordered 2 NC400 and 2 SMPS and await the email that they have shipped!

Welcome to the club!

My questions are as follows: Are there any disadvantages to putting two of these amps in one enclosure like siliconrays RE4307. Would it be better to get 2 RE2207's?

I would say it comes down to cost and form factor. Two amps in one box should not be an issue - some of us are putting 4 (or even more) nCores in the same box, and then getting rid of the heat is starting to become an issue.

I also need a little direction in picking out the best affordable XLR inputs, binding posts, and IEC sockets.

On the XLR's and IEC sockets, go for whatever normal stuff you have easily available locally. No real benefit from fancy stuff. On binding posts, just make sure they have enough current carrying capability and low resistance, as you don't want to hurt the damping factor (the output impedance of the nCore is *very* low). I am sure there will be people recommending fancy, expensive connectors, but the nCore really doesn't need any audiophile voodoo.

 

[matjans]

great to see this thread is still going on, well over the 4000 mark.

Anyway, as Julf said, no voodoo is necessary. Good quality mechanics are, however, in order to squeeze the most out of the ncore's so just get good quality connectors; neutrik xlr's (the de facto industrial standard, so to say), good quality speaker binding posts (if you ask Bruno, he'd say use neutrik speakon's), don't forget something like good spades for speaker cable connect.

mono vs stereo vs multichannel amp is more a matter of taste and budget (and waf) than true audio related i would think.

 

[Regnad]

So sorry if I have missed this, but...

Has anyone built a bridged NC400 unit yet that can report back on the method and results?

Thanks!