hypex ncore

[Simtu]

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]

Originally Posted by Simtu

...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]

Originally Posted by 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

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]

Originally Posted by Simtu

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]

Originally Posted by Simtu

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]

Originally Posted by ChrisPa

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]

Originally Posted by Abraxas336

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