I did remove the bulb, but stille running with a 1A fuse.
I already have 0.6v across the source resistors, but only 2.6V bias, probably because I use the Toshibas, think they have a lower turn on voltage.
I did post pictures a few pages back
But I will report back with my results - I feel that people often forget that.
I already have 0.6v across the source resistors, but only 2.6V bias, probably because I use the Toshibas, think they have a lower turn on voltage.
I did post pictures a few pages back
But I will report back with my results - I feel that people often forget that.
I have 0.6V across the source resistors, but there are no balance pots on the Cviller v2 boards, and I must admit that I didnt check if there is DC on the outputs.
I will do that when I have assembled the other side and powered it up again.
Thanks for your replies.
ZEN: IQ could be mistaken)
I will do that when I have assembled the other side and powered it up again.
Thanks for your replies.
ZEN: IQ could be mistaken
)
If you haven't checked for DC on output, you are not done.
Do that and adjust it out (below 10mV). You will use one pot, turn up or turn down, recheck .6V across source resistors, close on this voltage is OK f zero on output.
Rush
adjusting bias
I am just jumping in here. With much help from these forums, I built an F5. First class A MOSFET amp for me. Here is what I did FWIW.
As 6L6 said, put the top on (no need to screw down) and let the amp get to operating temperature. Keep one of the DVM monitoring a resistors and check voltages every 15 minutes. Another DVM monitoring speaker output. I started with bias at .5v and adjusted close to .6v, with just a few millivolts on the speaker leads. Another great tool was a cheap digital infrared thermometer. Mine was US $15 on a 'Deal of the Day' site. I checked the heatsink temperature when I checked the bias, every 15 minutes. Goal was to stay below room temperature +25C. Stablized at RT +22C, so heat was not a problem with the 4U case. You can also monitor FET output temperature, good for troubleshooting.
I hooked up an old iPod and looped on the music for about 4 hours. As the amp heated up, the bias did change slightly. At hour 4, the bias had not changed significantly in the previous hour. Time to tweak to .6v bias/ 0v output exactly, button it up and enjoy!
I am just jumping in here. With much help from these forums, I built an F5. First class A MOSFET amp for me. Here is what I did FWIW.
As 6L6 said, put the top on (no need to screw down) and let the amp get to operating temperature. Keep one of the DVM monitoring a resistors and check voltages every 15 minutes. Another DVM monitoring speaker output. I started with bias at .5v and adjusted close to .6v, with just a few millivolts on the speaker leads. Another great tool was a cheap digital infrared thermometer. Mine was US $15 on a 'Deal of the Day' site. I checked the heatsink temperature when I checked the bias, every 15 minutes. Goal was to stay below room temperature +25C. Stablized at RT +22C, so heat was not a problem with the 4U case. You can also monitor FET output temperature, good for troubleshooting.
I hooked up an old iPod and looped on the music for about 4 hours. As the amp heated up, the bias did change slightly. At hour 4, the bias had not changed significantly in the previous hour. Time to tweak to .6v bias/ 0v output exactly, button it up and enjoy!
Hi Rush,
I know - one channel still looks like spaghetti with leads pointing in all direction
I disassembled it in the process of fault finding.
So far it seems that my own failure where to turn the bias in the wrong direction at startup, and then I had the short in the PSU coil. Everything else seem to work like inteded - yet!
I know - one channel still looks like spaghetti with leads pointing in all direction
I disassembled it in the process of fault finding.
So far it seems that my own failure where to turn the bias in the wrong direction at startup, and then I had the short in the PSU coil. Everything else seem to work like inteded - yet!