Total draw is 5A. Should go for 3x at around 10A version for each channel.
Maybe rewire for two of these:
Mean Well MW LRS-200-24 24 VDC 8.5A 200W Regulated Switching Power Supply with Power Cables
Am I exaggerating or is 6A too low for two channels? Are SMPS more capable of delivering at their max rating?
Maybe rewire for two of these:
Mean Well MW LRS-200-24 24 VDC 8.5A 200W Regulated Switching Power Supply with Power Cables
Am I exaggerating or is 6A too low for two channels? Are SMPS more capable of delivering at their max rating?
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Hi CLiu,
24V x 2.5A = 60Watts
Wow, your MOSFETs are cooking right along. You might consider lowering your bias current a little bit. Papa Nelson wrote in one of the Zen articles about checking heatsink temps by hand.
Once the amp has come up to full temp:
If you can touch heat sink and feel like you can leave your hand there forever, 50'C or less.
If you can touch for 3 seconds before you have to pull hand away, 55'C.
If heat sink is untouchable, *OUCH*, 60'C or more.
The MOSFET junction temp is even higher than the heat sink temp. I try to shoot for the Goldie Locks, just right, 3 seconds, 55'C, for long MOSFET life. A slow, quiet fan blowing across heat sink can get you there if sink too small.
Have fun.
Cinco
24V x 2.5A = 60Watts
Wow, your MOSFETs are cooking right along. You might consider lowering your bias current a little bit. Papa Nelson wrote in one of the Zen articles about checking heatsink temps by hand.
Once the amp has come up to full temp:
If you can touch heat sink and feel like you can leave your hand there forever, 50'C or less.
If you can touch for 3 seconds before you have to pull hand away, 55'C.
If heat sink is untouchable, *OUCH*, 60'C or more.
The MOSFET junction temp is even higher than the heat sink temp. I try to shoot for the Goldie Locks, just right, 3 seconds, 55'C, for long MOSFET life. A slow, quiet fan blowing across heat sink can get you there if sink too small.
Have fun.
Cinco
I think I might not have enough space in the chasis for 2 of those. I might consider finding a unit that can supply larger current. Thanks for the advice.
I think the heatsinks are around 55'C at 2.5A. They feel hot to touch, but I can maintain my hands on them for 3-5 seconds. Also, in tropical Malaysia, the ceiling fan is always on, so it helps as well.
Yes. I think I did install the protection zener diode.
I can see that from the picture. The question is what killed the mosfet. It will be good to find that error before you install a new mosfet.
Ya, I am curious why the mosfet died. What could be possible reasons for mosfets to die half way like this? All I can think of now is too much heat. Any other possibilities?
Tip: Large washers with a small M3 hole are hard to find. I drill a coin (like a nickel or a penny) and those work well as MOSFET clamp washers. And they only cost at most, $0.05ea and plentiful.
Note the MOSFET washer on my M2X:
I will definitely try to use as big a washer as I can possibly manage. Thanks for sharing your pic!
MOSFET gates can be partially damaged during handling or assembly, they'll work alright for a while and then fail later. I had one like that in the voltage regulator of my Zen v4 amp. It worked partially but dropped 5 more volts than the other channel.
I've also instantly blown parts by powering up with bias all the way up... oops... oh, well just solder another part in.
Seems like your heat sinks are probably plenty big enough. The suggestions for bigger washers will help improve heat transfer.
Cinco
It could be too much heat caused by not having even pressure on mosfet or mosfet damaged by too much pressure or it could be a short. You can look at the isolation pad to see if it has been penetrated. I guess the hole in the IR mosfet version is electrical isolated like on e.g. Vishay version?
You can also check if the protection diode still works or the energy of a spark has been too much.
Can I use this type of aircond reactor to build MoFo? The spec is 8mH 10A. Thanks.
You want a microwave oven transformer, they look very similar but bigger. They are about 60mH and 10A. That's what I am using and works great.
Is the A-rating for DC current?
One of the reasons to have air gap in the core is if the chokes has to handle large DC current. Difficult to see from the pictures if chokes are "air gaped". But they seems large enough to handle the relative small "MoFo current"...….anyway….so many good alternatives to get cheap MoFo chokes!
One of the reasons to have air gap in the core is if the chokes has to handle large DC current. Difficult to see from the pictures if chokes are "air gaped". But they seems large enough to handle the relative small "MoFo current"...….anyway….so many good alternatives to get cheap MoFo chokes!