The problem is not completely on the L30D, it seems those 68 tiny 220 mf caps rated at 80 volts, should warm up with my 70 volts total passing thru, I m told , I m not sure, but the resistance is low, so....(?)
Some say that a 50% safety margin is recommended,so for 70v operating voltage should be used 100V rated capacitor,but this is just for pure safety,in practice I've never had any problems or excessive heat with 10V safety gap like you have,so you should be fine. Also they are rated at 105C I think,therefore if they are just a bit warm it's not a problem.
An 80V capacitor will tolerate 80V, so for 70V there is no need to use 100V.
Some may wear a life jacket under the shower, you can but do not need to.
If you run something unregulated, plan for 10% tolerance. If your 110V mains have 121V over voltage, the 70 V stage after the transformer will see 77 V. If lightning hits, even 500V caps won't save your amp.
With 50% over, probably some transistors will fail, sooner than the caps.
Capacitors should not heat up by them self's, just sitting in a power supply at idle. If a Chinese product does, maybe something is not quite right.
Some may wear a life jacket under the shower, you can but do not need to.
If you run something unregulated, plan for 10% tolerance. If your 110V mains have 121V over voltage, the 70 V stage after the transformer will see 77 V. If lightning hits, even 500V caps won't save your amp.
With 50% over, probably some transistors will fail, sooner than the caps.
Capacitors should not heat up by them self's, just sitting in a power supply at idle. If a Chinese product does, maybe something is not quite right.
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It looks like a neverending story for you,I hope your bad luck will end soon . I've always used SMPS power supplies for their compactness and easy to use and I have never had any problems. I've just received mine 70V 800W,I will try it soon with my new L30 module and let you know,hopefully this combo is better.
The underside looks like something shorted out on a solder joint, or somthing got very hot and the solder dripped and then shorted out. are you running a big subwoofer? if so you might be getting "buss pumping" and this can increase your supply voltage above what its supposed to be.
I guess the faulty ( fake ) power supply was the culprit, plus yes, the bottom of the pcb could have had a short circuit. The 220-12 safety circuit transformer also was gone. Mr Ljmaudio suggested me to use that power supply, apart from costing three times more, they are not so utterly good.
This looks like the starting point/short circuit. I am not surprised about the fake/faulty boards,I have experienced exactly the same thing with 2 tpa 3255 boards,one burned and one exploded,the bottom was black just like yours. Since then I check with a magnifier the soldering for anything suspicious or solder points too close and clean them if necessary. And of course I try to buy (amps and power supplies) only after at least a few reviews about them working ok.
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I know,that was exactly the case with my TPA 3255 boards,they worked for hours in different days then suddenly exploded and burned one after the other I was puzzled too,so I suppose it's either a bad/fake/unreliable part or some kind of conductive oxidation between very close solder points that evolves/advances in time. Anyway after that I gave up with them,,2 burnt boards was enough for me (in my case the SMPS power supply was and remained ok)
Good day. I need some help with a project. I am planning on purchasing four of the new L30d boards and bridging them to make a 2.0 system. My power supply is about 78v with no load. I am thinking it will be about 73v with the amplifiers. I also read that the boards are 2 ohms stable at those voltages. So is it posible to run 4 ohms in bridge mode without any problems. I plan on putting them in an old amplifier case with a fan blowing through their heatsink. Will post pics soon. Oh and to ensue we do not have a problem I plan on using two speaker protection boards just Incase. Any thoughts?
I tried a 4 ohm load with 78vdc supplies, the unit shorted and took the woofer out after about 15 minutes of running. Tried a second one, same… blew after 10 minutes. My guess… the boards don’t like higher rails… in the end I went with a different kit. Work’s fine!
Unfortunately my experience with the new L30D boards was utterly disappointing. They seemed to be very well built,but connected to a 70V smps and 6 ohm speakers their sound was fairly ok but their gain and power was extremely low! Much lower than my older 29x (times voltage) hifimediy T4 board,although they are supposed to be 40x. Also I estimate their power at 30W at the most (with=/- 70V power supply!). I tried 3 different preamps. Both L30D were the same,so after a few minutes i gave up on them. Fortunately I made one last try with a very small mono board,the same iraudamp7 design (irs 2092S/irf 4019) based on great reviews. Well,this time was exactly the opposite,I was truly impressed. Power supply +/- 48V. Great quality of sound,high gain and power without distorsion . Much better than my previous hifimediy T3 and t4 and also TPA 3255,and incomparable to the new L30D. So I will look no further,I ordered 2 more and they are my choice for the amp I will build in the summer. In conclusion maybe I was unlucky,but my advice would be against the new L30D boards.
Thank you for the responses its was really helpful. have anyone had any experience with the L25 it looks good. That would be my next option. What I want is an amplifier powerful enough to give at lease 600w at 4ohms stable without breaking the bank. The power supply I own is rated 73v however when I tested without load it's 78v, I'm guessing it might go down with the amplifier connected.
As far as I know the L25 is designed for 8 ohm load,at 4 ohm it becames unstable at the least. You can see that in his specs and reviews. There are many types of IRS2092+IR mosfet based boards available for different loads and different powers everywhere (ebay,aliexpress,amazon,audiophonics,sure/wondom etc). If you want only a LJM amp board here is a summary of them (load,power) from the designer himself. 
For example here you have a wide offer and the brand has good reviews. https://store.sure-electronics.com/list/3