Smoke comes from resistors and transformers, capacitors go bang and semi's go pfffft. I have had the 0.47R resistors get somewhat fried in an F5, but never to the point where they had to be replaced.
Ok then let's assume it was a resistor that smoked (no ffft, no bang), but not to the point that it needs to be replaced. What are my options?
Were you getting any voltage across the speaker outputs on the bad channel?
I went to 4 output devices per channel and for some reason one channel kept blowing the K170 JFET - small puff of smoke and then full rail voltage on the outputs.
I went to Toshiba outputs X 4 per channel and been over a year with moderate use and the K170 has been happy.
Never really understood what was happening other than maybe the MOSFETS were not as closely matched as the Toshibas?
I went to 4 output devices per channel and for some reason one channel kept blowing the K170 JFET - small puff of smoke and then full rail voltage on the outputs.
I went to Toshiba outputs X 4 per channel and been over a year with moderate use and the K170 has been happy.
Never really understood what was happening other than maybe the MOSFETS were not as closely matched as the Toshibas?
hey Studiostevus,
Just a couple of Ideas for you ,OHM out all the resistors with your meter,also verify the correct ones are in place,If you didn't clean off the flux do it and take a good look for shorts,you can hook up the working side and make voltage and at some places resistance measurements and then compare them to the bad channel ,You can take the fets out and test them or at least ohm them out or of course replace them,,,good luck and I hope you get it going! one other thing you can connect your meter to the PS and check each time you change something in the circuit ,some times parts are bad but don't smoke until a load is on them.
Just a couple of Ideas for you ,OHM out all the resistors with your meter,also verify the correct ones are in place,If you didn't clean off the flux do it and take a good look for shorts,you can hook up the working side and make voltage and at some places resistance measurements and then compare them to the bad channel ,You can take the fets out and test them or at least ohm them out or of course replace them,,,good luck and I hope you get it going! one other thing you can connect your meter to the PS and check each time you change something in the circuit ,some times parts are bad but don't smoke until a load is on them.
turned on the pre-amp, then Phutt.
Did the pre-amp send some pulsing down the interconnect?
Does the pre-amp mute, or isolate the hot signal pole at shut down/start up?
Does the lack of a RF filter allow some kind of temporary oscillation in, that the pre-amp sends out only during start up?
Did the pre-amp send some pulsing down the interconnect?
Does the pre-amp mute, or isolate the hot signal pole at shut down/start up?
Does the lack of a RF filter allow some kind of temporary oscillation in, that the pre-amp sends out only during start up?
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1. Successfully completed, biased to 0.1mV DC offset and 0.595V bias.
2. Started with 4Ohm resistor and a soundcard as input. No smoke, but I measure 22mV across the resistor and 0.59V bias.
I probably need to rebias. Should I short input to GND?EDIT: scrap that... on the scope I see output, nice and clean from my soundcard. The 22mV across the resistor can also stem from the soundcard... when I increase volume on the card (without playing signal) it corrects to 0V and into the minus mV range...
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Step 3:
3. I first measured for any DC voltage on the output of the preamp. There was none. Then I started the equipment according the right order (source, preamp, F5). I have deliberately waited until the voltage of the preamp had settled. So then I started the F5 and ..... SMOKE !!!!
I couldnt clearly see where it came from, as I was too busy with switching everything off. I could however see the voltage across the Speaker resistor (4ohms) climbing.
What is going on here? Step 2 went fine (with soundcard as input), but step 3 (preamp as input) went wrong again?? Oscillations?
3. I first measured for any DC voltage on the output of the preamp. There was none. Then I started the equipment according the right order (source, preamp, F5). I have deliberately waited until the voltage of the preamp had settled. So then I started the F5 and ..... SMOKE !!!!
I couldnt clearly see where it came from, as I was too busy with switching everything off. I could however see the voltage across the Speaker resistor (4ohms) climbing.
What is going on here? Step 2 went fine (with soundcard as input), but step 3 (preamp as input) went wrong again?? Oscillations?
