Hey guys. I just put together my first amp, the 3886 kit from chipamp.com. I used an old computer power supply for its power entry module. When i hooked up my transformer, an antek 300va 22v, and plugged it in to test if the rectifier was working (it is, led light was lit), it heated up really fast and started smoking. I immediately unplugged it. I double checked my wiring and everything seems correct. Is it a faulty transformer or maybe faulty power entry on the PS? Thanks for any help.
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Looks like one primary is connected to mains and the other shorted with a switch. That will generate (some) heat. Don't test it until you have build a lamp tester. The transformer and switch are probably damaged (destroyed) and need careful testing before using again.
Photo's of transformer label and switch would help.
Photo's of transformer label and switch would help.
mra185, i kinda didnt know what to do with the voltage selector, especially since the transformer doesnt have that many wires lol, so i just left it alone. I only wired the power entry and on/off switch.
Also, should i have grounded to the purple wire to the chassis as well?
Heres better pictures of the mains wiring and a pic of the transformer label.
Also, should i have grounded to the purple wire to the chassis as well?
Heres better pictures of the mains wiring and a pic of the transformer label.
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Are you using 110 or 220 for line?
For 110 both black wires from the transformer should go to the N (neutral) of the power connector. Then both red wires should go to one side of the switch. Then another separate wire should go from the other side of the switch to the side tab of your fuse holder and another separate wire from the end of the fuse holder to the L (line or hot) side of your power entry connector. ( heat shrink over all wire ends )
For 220 one black wire from the transformer should go to the N (neutral) of the power connector. The red wire from that winding should connect to the black wire of the other winding. The red wire form that other winding should go to one side of the switch. Then another separate wire should go from the other side of the switch to the side tab of your fuse holder and another separate wire from the end of the fuse holder to the L (line or hot) side of your power entry connector. ( heat shrink over all wire ends )
Ground the purple wire.
You will not be able to use the voltage selection switch with a transformer...it is only a SPST and the SMPS was designed to use it.
Use a "light bulb" tester as Mark Whitney suggested...and a fused input!
One step at a time...disconnect the secondaries until it operates safe without a load...then proceed.
Hope that helps.
For 110 both black wires from the transformer should go to the N (neutral) of the power connector. Then both red wires should go to one side of the switch. Then another separate wire should go from the other side of the switch to the side tab of your fuse holder and another separate wire from the end of the fuse holder to the L (line or hot) side of your power entry connector. ( heat shrink over all wire ends )
For 220 one black wire from the transformer should go to the N (neutral) of the power connector. The red wire from that winding should connect to the black wire of the other winding. The red wire form that other winding should go to one side of the switch. Then another separate wire should go from the other side of the switch to the side tab of your fuse holder and another separate wire from the end of the fuse holder to the L (line or hot) side of your power entry connector. ( heat shrink over all wire ends )
Ground the purple wire.
You will not be able to use the voltage selection switch with a transformer...it is only a SPST and the SMPS was designed to use it.
Use a "light bulb" tester as Mark Whitney suggested...and a fused input!
One step at a time...disconnect the secondaries until it operates safe without a load...then proceed.
Hope that helps.
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DUG, thank you so much! I wired it exactly like you said and no more smoke!
Now i ran into another problem. I finished wiring and hooking up everything, turned it on but theres no sound coming from the speakers. Not even a hum/hiss when the amp is on. The led light is on, the voltage from the secondaries from the rectifier is around 28v. What could be the problem?
Heres pics of my wiring. Please please please pay no attention to my lack of enclosure and the overrall 'rawness' of the setup. This is merely to test to see if it works at all before i put it in a chassis and make it look pretty.
Any help for this noobie will be greatly appreciated.
Now i ran into another problem. I finished wiring and hooking up everything, turned it on but theres no sound coming from the speakers. Not even a hum/hiss when the amp is on. The led light is on, the voltage from the secondaries from the rectifier is around 28v. What could be the problem?
Heres pics of my wiring. Please please please pay no attention to my lack of enclosure and the overrall 'rawness' of the setup. This is merely to test to see if it works at all before i put it in a chassis and make it look pretty.
Any help for this noobie will be greatly appreciated.
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OK so once i put the Rm in it worked! Amp is running fine so far but is there a burn in period, my crappy soldering or is it because the transformer overheated previously because the sound seems a little muddy and the highs are barely there.... I wish i could hear a well put together chipamp so i could get a reference to the sound.
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Yeah... It seems "grounding" and "fake" are commonly used words to explain why something doesn't work or doesn't work well.
I doubt "grounding" is the issue. As long as all ground connections in the circuit have a good connection to ground and the IC is not oscillating or overheating, you should get performance that sounds pretty decent. You won't get the best measured performance (the THD above 1 kHz will suffer) and you may have issues with hum, but those aside, the amp should sound decent.
I am still blown back that you got the transformer to smoke without blowing the mains fuse - or even tripping the circuit breaker. That's pretty scary. I suggest testing it with a resistive load. It should be able to deliver the voltages and currents specified without overheating. If it doesn't pass that test, I suggest getting another transformer.
Unfortunately, diagnosing your amplifier from statements like "the highs are barely there" and "the sound seems muddy" will be a challenge. I suggest making some measurements of the frequency response to start with. The free version of TrueRTA along with a sound card and a resistive divider (say, 10:1) would give you much more insight than any guesses you'll pick up here.
~Tom
your screw is touching top of that computer psu box and makes shorted turn ! (first picture) offcourse if you closed that box at all
how i wish you live in an old house with few laptops and pc smpsu (sometimes induction cooker)and bad earth so that you can fell grounding issues on your skin and why always such attitude who are you at all???
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