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I did all that work, and I replaced transistors, diodes, resistors, op-amps, ultrasonic cleaning, and I forgot that one? ground.
Nope
I am so embarrassed. I should LIE. I missed the speaker ground on the "bad" channel. Little bit of DC offset over there, and none! on the other channel
I cannot set the bias properly because there is someone sleeping here, but tomorrow I Will get-r-done.
BTW even at low levels, and crap test speakers it sound Soo sweet
I did all that work, and I replaced transistors, diodes, resistors, op-amps, ultrasonic cleaning, and I forgot that one? ground.
Nope
I am so embarrassed. I should LIE. I missed the speaker ground on the "bad" channel. Little bit of DC offset over there, and none! on the other channel
I cannot set the bias properly because there is someone sleeping here, but tomorrow I Will get-r-done. BTW even at low levels, and crap test speakers it sound Soo sweet
Well everything has smoothed out, and the sound is nice, and clean. Very pleased.
I just bought a GFA-555 transfo, and I can't figure out where the 120, and neutral go.
Anyone have a PDF of the GFA manual?
Thanks
Ben
http://www.diyaudio.com/forums/showthread.php?s=&threadid=117074
I just bought a GFA-555 transfo, and I can't figure out where the 120, and neutral go.
Anyone have a PDF of the GFA manual?
Thanks
Ben
http://www.diyaudio.com/forums/showthread.php?s=&threadid=117074
the soft start resistor is just that....for a soft start. Instead of hitting the transformer with the full 120 off the wall, and jolting everything to life, they run it through the soft start resistor for a few seconds, till the caps are partially charged and then the relay on the board basically jumpers the resistor out of the circuit, giving you full power to the primary of the transformer.
The resistor should be hot, because it drops a pretty large voltage across it but then it is taken out of the circuit. If the resistor gets hot and stays hot, then the relay isnt doing its job, or the circuitry that controls the relay is kaput.
In the event that the relay ISN'T working, then the 120 is going through the resistor all the time and it will get hot and burn out. Also, your amp will be operating as if in a brownout. This will stress the circuitry on the bias board even more to try and keep the amp stable, because with that resistor in there all the time, you are starving the amp for voltage and current.
I will hunt up my schematic and see what the possible causes might be. laters...Rob
The resistor should be hot, because it drops a pretty large voltage across it but then it is taken out of the circuit. If the resistor gets hot and stays hot, then the relay isnt doing its job, or the circuitry that controls the relay is kaput.
In the event that the relay ISN'T working, then the 120 is going through the resistor all the time and it will get hot and burn out. Also, your amp will be operating as if in a brownout. This will stress the circuitry on the bias board even more to try and keep the amp stable, because with that resistor in there all the time, you are starving the amp for voltage and current.
I will hunt up my schematic and see what the possible causes might be. laters...Rob
Hi musinteg,
The amplifier will be running at reduced voltages, but this will not stress anything except the soft start resistor. That will burn out before too long.
HI Ben,
These amps are designed for 4 ohm minimum, stable if the load drops briefly to 2 ohms.
Why would you want to do this? Sound quality goes down as the load impedance goes down.
The 680 R resistor is a dropping resistor for the soft start circuit. It runs very warm to hot. That is normal. The surge resistor should be on the order of 4.7 to 10 ohms. Something close to that range. It normally may warm up during start, but then runs at ambient temperature. It will only get hot if there is a failure somewhere.
Check the solder connections on the soft start PCB. The relay may have burned contacts. Do you hear it go "Click"?
-Chris
Completely untrue.
The amplifier will be running at reduced voltages, but this will not stress anything except the soft start resistor. That will burn out before too long.
HI Ben,
No.
These amps are designed for 4 ohm minimum, stable if the load drops briefly to 2 ohms.
Why would you want to do this? Sound quality goes down as the load impedance goes down.
The 680 R resistor is a dropping resistor for the soft start circuit. It runs very warm to hot. That is normal. The surge resistor should be on the order of 4.7 to 10 ohms. Something close to that range. It normally may warm up during start, but then runs at ambient temperature. It will only get hot if there is a failure somewhere.
Check the solder connections on the soft start PCB. The relay may have burned contacts. Do you hear it go "Click"?
-Chris
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