2 x Hypex SMPS1200 dead following power cut

We had a power cut last night, once it came back, everything turned on as normal... except my two DIY Hypex monoblocks.

Specifically, both SMPS1200A700 modules have stopped providing any DC power. There is no relay "click", nothing.

- The fuses are fine
- The current inflow thermistors are fine (I had to replace one of these before)
- The main capacitors are charging
- I've tried letting the main capacitors discharge fully before powering on again - no change
- I have checked on other power outlets - no change
- I have tested with and without NCORE modules hooked up

According to the HYPEX data sheet, the SMPS can be latched off if the NCORE module sees a fault, but this should be unlatched after capacitor discharge.

There is also the following in the datasheet, but no more details of how it works:
"The supply is triggered for normal operation or latched off in case of critical fault via in built-in actuators."

Does anyone have any ideas for common faults/diagnosis? The fact they both failed in the same way seems suspicious, and I really don't want to drop >400Eur on two new SMPS if it's just a fault-protection, then wait for the next power cut...
 
It generally isn't the power cut that causes damage, it is when the power comes back on and there is a large mains spike. That is what does the damage.
Did you have a storm when this failed ... there is the usual household versus electricity provider claim to be looked into.
Household insurance usually covers damage and as you didn't cause it, it could be construed as accidental.
 
Thanks for your suggestions.

I will look into claiming on insurace, but I'm not too optimistic since these are DIY components rather than a finished product. There was no storm, it just seems that a couple of streets went out.

I can't see any MOV, only the current inrush thermistors, which are fine. As said, the weird thing is that the main filter capactiors are charging as normal, so the issue must be further down the chain.
 
In general fixing smps may be rather tricky. My advise is to check the datasheet of the oscillator chip and see which pin is used for protection. See what state it should be or pulled to ground or high (5v or so) This should lead you as you follow back. You will may find an opamp that is sampling the mains input for high and low voltage input. You should also check if any high value resistors in this chain as often they go open circuit. check also any zener diodes that are used as references with this opamp.
Check also any capacitors if you have any of them used to trigger any power mosfets or transistors.
Lastly try to get hold of a schematic of the smps as this will help you a lot to analyze the fault and see what is going on. Try to find the model number and start an on line search for it.
Be careful as you are dealing with high DC voltage (320v or more) always use a series 100w bulb tied to the input voltage supply to serve as a current limiter as if any errors occur you will avoid any explosions :)
Good luck
 
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Thank you for all the very useful advice.
I contacted Hypex who recommended replacing one capacitor in particular. I will try this - if it doesn't work, I may stop and replace both SMPS.

The amps have been on almost continuously for >5 years in relatively tight cases (Ghent audio), in a climate that gets hot in the summer. I wonder if the Su'scon caps have just had enough.
 
Thank you for all the very useful advice.
I contacted Hypex who recommended replacing one capacitor in particular. I will try this - if it doesn't work, I may stop and replace both SMPS.

The amps have been on almost continuously for >5 years in relatively tight cases (Ghent audio), in a climate that gets hot in the summer. I wonder if the Su'scon caps have just had enough.

Possibly gone short caused by over voltage, so you can check with a multi meter.
 
After changing both 220uf (as recommended by Hypex), both modules are working again! 400+ euro saved...

Thanks again for pointers and recommendations.

In case anyone has this issue in the future, the capacitors are C38 & C39, 220uf 35v. The old ones measure fine in terms of capacitance and ESR, but they must have been leaky or otherwise misbehaving at voltage.

I replaced with 2 x 220uf 50v, I had to cut out and remove one of the big filter caps to access one of them.
 
After changing both 220uf (as recommended by Hypex), both modules are working again! 400+ euro saved...

Thanks again for pointers and recommendations.

In case anyone has this issue in the future, the capacitors are C38 & C39, 220uf 35v. The old ones measure fine in terms of capacitance and ESR, but they must have been leaky or otherwise misbehaving at voltage.

I replaced with 2 x 220uf 50v, I had to cut out and remove one of the big filter caps to access one of them.
Found the same. This is the second time, the first time I just had them repaired by an electronics shop, and some Nichicon were put in instead of the Suscicon's from Hypex. My C38 is bulging, so removed it, but I am not sure what type of cap this is: searching the name "Right and Yubr_" and finding nothing. The amps (the SMPS1200 PS) worked fine for 4 years the first time, now it lasted only 1.5 years before one channel quitting.
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It sounds like this C38 (and C39) caps take quite a beating for some reason, so I bought some of these to replace it. I looked for the longest lasting (most durable) 220 uf Nichicon I could find with a 10mm diameter; I am no expert here but I read that a higher voltage doesn't hurt either. Hopefully they will be good for a few more years.

https://www.digikey.com/en/products/detail/nichicon/UHW1K221MPD1TD/5818047