i already post picture in #3042.that heat sink wieght is only 300gms without fan but i use only for test.my final heatsink will be heavy now i am waiting for 2u case which i already ordered.sometimes mosfet are good with meter but some time they unable to switch off even they are order to off by ic.they will off only after restart.check your amp heat without hv.
in my amp voltage remain same.when step is not working it mean hv is in open position.in open position how voltage can drop.i have hundred idea to check everything.first check capacitor connection then check reason of drop volatge.droping is by psu or by amp.to check psu attach both hv wire with two iron I core or any iron sheet.put water in jar and put this iron piece in water with difference of four or five inch then check voltage positin if it drop or not.there should be no current flowing for check the current use a digital ampere meter on primary or secondary no matter. all professional use this method to check transfomer and genretor load capacity.for heavy load they use also salt with water. when ac volatge start to drop 5% in secondary then check the current in primary.this is the true power of a transformer.in simple method attach a 100w bulb on hv and then check.after this you can know where is fault.
first check heat without hv if it normal then heat is come from hv.if not check mje and output transistor they may be fake.
it mean fault in mosfet or ir 2117 circuit.now check which side is going hot quicky.negative side or postive side.then check that side circuit of stepper.
Check the bias. This means that You have to measure the voltage across the 0.33ohm emitter resistors.
Sajti
i am new of this trend.. i want to build this amp sir do you a PCB layout of pagarigan amp of yours?
I know but Re 0.33e does not showing any voltage reading like from 5mv to10mv that we want
That is OK in case of heating...
Is the heatsink hot, without any signal?
What kind of fan are You using? I mean size, speed/rotation.
Sajti
i think you didn't get my point.negative side mean npn transistor and positive mean pnp side.fault is not in your bias fault is in mosfet circuit and ic circuit.heat sink and fan not a matter when so much heat come.because h class amp known as low heat amp if you get heat then its ab class amp.you are first guy who has face this probelm.its realy painful after hard work.