I got an interesting info from Hypex about the adapter board they are selling, that I though I would share here as the main ncore thread is now closed for good.
The SMPS600 is often preferred to the SMPS1200 when used with the nc400 as it does provide the necessary Vdr (16V min) to prevent the use of the internal regulator of the nc400n thus saving ~5W of power dissipation.
The SMPS1200A400 only provides 15.6V, which is sadly not enough for the need here (albeit it might work...).
So, going back to the adapter, it appears it does include a diode that raises the effective Vdr by 1V, making it just right for the nc400
A simple SMPS1200 now appears to be a no-brainer solution compared to two SMPS600 when powering a pair of nc400, as it is the same price as a SMPS600, has what appears to be a better heatsink design, and only dissipate 1.5W more watts than a single SMPS600 when idle (9W vs 7.5W), so 6W less than a pair of SMPS600.
Oh, and it does have a clean dual adapter solution to connect the modules, saving the trouble of building a Y cable
The SMPS600 is often preferred to the SMPS1200 when used with the nc400 as it does provide the necessary Vdr (16V min) to prevent the use of the internal regulator of the nc400n thus saving ~5W of power dissipation.
The SMPS1200A400 only provides 15.6V, which is sadly not enough for the need here (albeit it might work...).
So, going back to the adapter, it appears it does include a diode that raises the effective Vdr by 1V, making it just right for the nc400
A simple SMPS1200 now appears to be a no-brainer solution compared to two SMPS600 when powering a pair of nc400, as it is the same price as a SMPS600, has what appears to be a better heatsink design, and only dissipate 1.5W more watts than a single SMPS600 when idle (9W vs 7.5W), so 6W less than a pair of SMPS600.
Oh, and it does have a clean dual adapter solution to connect the modules, saving the trouble of building a Y cable
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Just stumbled across this thread as i have the adapter board in question. I've ordered some parts from Hypex not so long ago and they kindly offered this adapter. Managed to elevate the pater PCB board (above the PSU) by using long plastic spacer on one of the SMPS12400 PSU mounting screws. I really appreciate SMPS1200 heatsink design, as I could apply the thermal paste underneath for better contact with the case, so that heat is transferred to the case itself, acting as one big heatsink (same procedure was put in place for NC400 modules)
Here is the photo of the new set-up.
Here is the photo of the new set-up.
An externally hosted image should be here but it was not working when we last tested it.
Put this diode mod in, saw no difference in heat at idle. After contacting Hypex, they kindly responded with (FYI):
"We’ve recently discovered this does not really work as intended. So better leave the diode out and connect VdrN directly to V- rails."
Online hypex store still shows the diode in the connector board. No response when I asked if the diode was detrimental or innocuous which tells me its probably better to remove it.
"We’ve recently discovered this does not really work as intended. So better leave the diode out and connect VdrN directly to V- rails."
Online hypex store still shows the diode in the connector board. No response when I asked if the diode was detrimental or innocuous which tells me its probably better to remove it.
My nc400 looks to need a recapping after roughly 4 years, at least some of the SMPS caps appear to be getting weak, it won't always startup on a cold start anymore, sometimes taking an hour to finally power on. (accidentally found this out one day when I left it turned on and left music playing)
That said, this comes back to the 10W of waste heat the amp consumes doing SFA due to the reasonings Hypex have for keeping the SMPS1200 @15.6V vdr in the first place, one would have thought they have a jumper for the DIY nc400 modules in a newer revision SMPS1200 for a 15.6/16V switch, and yes they have revised the PSU at least once or twice.
I have ordered a tiny 15VA 18/18V toroid (after having success using 3 of these really cute things in my dam1021 build), to add the required floating 16-24V (big range) regulated Vdr for the nc400, reducing its effective idle dissipation.
That said, this comes back to the 10W of waste heat the amp consumes doing SFA due to the reasonings Hypex have for keeping the SMPS1200 @15.6V vdr in the first place, one would have thought they have a jumper for the DIY nc400 modules in a newer revision SMPS1200 for a 15.6/16V switch, and yes they have revised the PSU at least once or twice.
I have ordered a tiny 15VA 18/18V toroid (after having success using 3 of these really cute things in my dam1021 build), to add the required floating 16-24V (big range) regulated Vdr for the nc400, reducing its effective idle dissipation.
Wow, this is extremely disturbing!! I’ve had mine for longer than that... better check them out
Wow, this is extremely disturbing!! I’ve had mine for longer than that... better check them out
It turns out most of the amp is in good health, the large softstart PTC was however blown and thus the main caps were taking 2 hours to charge up. I only got around to getting a better look at it.
I'll be experimenting with my own linear transformer based Vdr implementation in the coming days, will be interesting to see how the idle dissipation fares after the fact. The regulator will be a TPS7A4701 that will be set to ~16VDC fed via a small 15VA 18VAC toroid.
I wish to get the linear losses as low as possible and this one seems to be a good fit with relation to compatible output voltages. nc400 vdr range is 16-25V, will tweak to minimize losses in relation to the nc400 vdr regulation & the TPS7A4701 dissipation.
I wish to get the linear losses as low as possible and this one seems to be a good fit with relation to compatible output voltages. nc400 vdr range is 16-25V, will tweak to minimize losses in relation to the nc400 vdr regulation & the TPS7A4701 dissipation.
First impression is that it works, no perceivable difference in overall SQ.
Setting the regulator to 16.2V didn't work at all which is what I expected when the SMPS1200 voltage was that to begin with, would make sense why the silly diode mod wouldn't work.
It was when I set 17.5V is when it began drawing 100mA approx on the Vdr line, each nc400 consuming approx 50mA @ 17.5Vdr. Does hypex not publish proper specifications of the current draw of Vdr? The nc400 datasheet is useless all things considered. I will test higher Vdr and measure the difference in current draw.
Setting the regulator to 16.2V didn't work at all which is what I expected when the SMPS1200 voltage was that to begin with, would make sense why the silly diode mod wouldn't work.
It was when I set 17.5V is when it began drawing 100mA approx on the Vdr line, each nc400 consuming approx 50mA @ 17.5Vdr. Does hypex not publish proper specifications of the current draw of Vdr? The nc400 datasheet is useless all things considered. I will test higher Vdr and measure the difference in current draw.
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Why does the nc400 declare it requires 16V minimum Vdr when the SMPS1200 outputs 16.2Vdr which clearly isn't enough?
The SMPS600 outputs 17Vdr thats why. nc400 datasheet is BS. It should accurately state below ~16.5V (or 17V?) the internal regulator takes over, as we wouldn't be having this 10W discussion if the datasheet were correct.
The SMPS600 outputs 17Vdr thats why. nc400 datasheet is BS. It should accurately state below ~16.5V (or 17V?) the internal regulator takes over, as we wouldn't be having this 10W discussion if the datasheet were correct.
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I've been running at 17.5Vdr and all is well. Will post pictures after I permanently mount the transformer. I ended up replacing my SMPS1200 due to the softstart not working correctly or not at all, however I later found that one of the filter caps had physically detached from the board via a press ring. Probably due to the many heating and cooling cycles this thing has had to endure. It will have a significantly longer lifespan now that 10W of heat isn't being dumped into its confines.
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