Hello all,
I am cleaning up an old Traynor YPM-250 power amp which is functional. Does anyone know the correct procedure to adjust the output bias using R10 which is a 470R pot? Attached are the applicable schematics. I contacted the manufacturer, they had no further information.
Similar Traynor amps such as the PM-300 say to adjust for 10mV across a custom nichrome wire resistor, however the YPM-250 does not utilize this configuration.
Thanks in advance.
I am cleaning up an old Traynor YPM-250 power amp which is functional. Does anyone know the correct procedure to adjust the output bias using R10 which is a 470R pot? Attached are the applicable schematics. I contacted the manufacturer, they had no further information.
Similar Traynor amps such as the PM-300 say to adjust for 10mV across a custom nichrome wire resistor, however the YPM-250 does not utilize this configuration.
Thanks in advance.
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I always used to place my mV meter acoss R28 and adjust R10 for 5 mVolts.
That gives enogh current to ensure all four output transistors are just turned on (drawing about 45mA), ensuring minimal crossover distortion.
That gives enogh current to ensure all four output transistors are just turned on (drawing about 45mA), ensuring minimal crossover distortion.
Hey, thanks Jon. Without disturbing R10 I've measured R28 (0.27R 5W) and it is presently dropping around 2mV (same for the other three). I calculate about 7.5 mA.
For 5mV I calculate that would be 18.5mA. Am I intepreting this incorrectly?
Also, would I be better to connect an 8R dummy load with an oscilloscope and then adjust R10 for minimum crossover distortion?
For 5mV I calculate that would be 18.5mA. Am I intepreting this incorrectly?
Also, would I be better to connect an 8R dummy load with an oscilloscope and then adjust R10 for minimum crossover distortion?