I've been building this uzzors2k's SMPS:
http://uzzors2k.4hv.org/index.php?page=benchsmps1
There has been already 3 pairs of dead mosfets so little advice would be definitely needed!
I haven't connected the GDT to the power section yet, so IRFP450s' gates are not connected to anything. For 250V 3.3µF and 250V 3µF capacitors I'm using these:
http://www.ebay.com/itm/Yellow-3-3u...al_Components_Supplies_ET&hash=item53f28549fb
I do not know much about mosfets but according my test with two IRFP450 connected to each other like in SMPS's schematics, if there is voltage on connection of source and drain, the mosfets will open. I noticed this by using my linear power source.
The strange phenomena that concerns me is that if the mosfets are not connected the circuit and I power it on, there's about 150 volts on that source-drain connection point, though it starts to decrease when I measure it towards negative rail. But that part of circuit is DC and according my knowledge DC won't go through capacitors. But because this DC is rectified from mains, could it be that ripple voltage is causing this voltage? And by plugging voltage meter to it it would draw that minimal current slowly because of voltage meters high impedance?
The ripple is about 8 volts and 50Hz measured by oscilloscope:
1volt/DIV and 5ms/DIV
So are my capacitors right type or what should I do? Bleed the source-drain current to negative rail? I have only one try after which I'll have to buy more mosfets!
http://uzzors2k.4hv.org/index.php?page=benchsmps1
There has been already 3 pairs of dead mosfets so little advice would be definitely needed!
I haven't connected the GDT to the power section yet, so IRFP450s' gates are not connected to anything. For 250V 3.3µF and 250V 3µF capacitors I'm using these:
http://www.ebay.com/itm/Yellow-3-3u...al_Components_Supplies_ET&hash=item53f28549fb
I do not know much about mosfets but according my test with two IRFP450 connected to each other like in SMPS's schematics, if there is voltage on connection of source and drain, the mosfets will open. I noticed this by using my linear power source.
The strange phenomena that concerns me is that if the mosfets are not connected the circuit and I power it on, there's about 150 volts on that source-drain connection point, though it starts to decrease when I measure it towards negative rail. But that part of circuit is DC and according my knowledge DC won't go through capacitors. But because this DC is rectified from mains, could it be that ripple voltage is causing this voltage? And by plugging voltage meter to it it would draw that minimal current slowly because of voltage meters high impedance?
The ripple is about 8 volts and 50Hz measured by oscilloscope:
1volt/DIV and 5ms/DIV
So are my capacitors right type or what should I do? Bleed the source-drain current to negative rail? I have only one try after which I'll have to buy more mosfets!
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