ok, so a few days ago i found a lm12clk dual mono amp kit here in japan, it does not show what the input voltages are exactly, but from the horribly printed power supply schematic that it came with it has two +10-25v, two -10-25v and an E voltage input, the power supply schematic that it came with is very basic, it has a transformer, diode bridge and 2 4700-10000uf capacitors, it does not show the capacitor polarity.
i bought a sinko transformer 3amp max with inputs for 90, 100, and 110 volts and outputs for 0, 0, 17.5, 28, and 35 volts, i got a small 4amp diode bridge that should be more then enough, and two nippon chemi-con 10000uf 35v capacitors.
the first try i used the 28volt outputs on the capacitor to the diode bridge and got 24 volts dc out of the diode bridge, then i hooked up the two capacitors with the negative of one wired to the positive of the other and the voltage across the open positive and negative ends of the capacitors, i didnt check the voltage and i hooked them up to the first amp along with the 0 out from the transformer as it said in the schematic, plugged it in and POP!! two small transistors exploded, so i went back to figure out where i went wrong.
then i tested wiring straight from the diode bridge on the good amp half to see if the kit actually worked on those voltages (not the best idea i know, but it was a cheap kit and i didnt really care much) and it powered up fine, but it only made a bunch of noise on the speaker since it was un filtered power.
then i tried using a 25volt power supply that i have (it doesnt have the 0v out) and i got some staticy sound! but the pre-amp section didnt power up due to the missing 0volt input. but that showed me that there is some hope for this little kit.
then i tried getting voltages from a few different setups on the capacitors, first i wired the capacitors the same as the first test except this time i put the 0 out from the capacitor on the wire that was tieing the two capacitors together and the outputs were about 70 volts dc! and each capacitor had almost 40 volts on it! i know that would blow up the amp for sure! then i tried with only one capacitor and the 25volt out from the diode bridge turned into 35 volts when connected to the capacitor.
so what am i doing wrong? how do i get the voltages to what i need?
i bought a sinko transformer 3amp max with inputs for 90, 100, and 110 volts and outputs for 0, 0, 17.5, 28, and 35 volts, i got a small 4amp diode bridge that should be more then enough, and two nippon chemi-con 10000uf 35v capacitors.
the first try i used the 28volt outputs on the capacitor to the diode bridge and got 24 volts dc out of the diode bridge, then i hooked up the two capacitors with the negative of one wired to the positive of the other and the voltage across the open positive and negative ends of the capacitors, i didnt check the voltage and i hooked them up to the first amp along with the 0 out from the transformer as it said in the schematic, plugged it in and POP!! two small transistors exploded, so i went back to figure out where i went wrong.
then i tested wiring straight from the diode bridge on the good amp half to see if the kit actually worked on those voltages (not the best idea i know, but it was a cheap kit and i didnt really care much) and it powered up fine, but it only made a bunch of noise on the speaker since it was un filtered power.
then i tried using a 25volt power supply that i have (it doesnt have the 0v out) and i got some staticy sound! but the pre-amp section didnt power up due to the missing 0volt input. but that showed me that there is some hope for this little kit.
then i tried getting voltages from a few different setups on the capacitors, first i wired the capacitors the same as the first test except this time i put the 0 out from the capacitor on the wire that was tieing the two capacitors together and the outputs were about 70 volts dc! and each capacitor had almost 40 volts on it! i know that would blow up the amp for sure! then i tried with only one capacitor and the 25volt out from the diode bridge turned into 35 volts when connected to the capacitor.
so what am i doing wrong? how do i get the voltages to what i need?
