I have a mint original R-1050 that I am tuning up and I want to set the bias. My PB-1062 board has no fuses? They were jumpered out at the factory it appears as the solder points are undisturbed. Do I just cut the jumpers?
Thoughts on setting bias Luxman R-1050
- Thread starter jefferylhenr
- Start date
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- bias adjustement luxman r-1050
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Just my opinion, but the factory instructions detail a pretty poor method for adjusting bias. The fuses (which are not present in your unit) serve the complete AF section, and not just the output devices. As such, that method cannot be relied upon to indicate actual bias (idle) current separately from the rest of the circuit.
It would seem more appropriate to connect a millvolt meter across the emitter ends of R120 and R121 to monitor voltage drop through the total 0.66Ω stack, then calculate current. Given that the outputs are identical to those in a Pioneer SX-750, and those seem to work well with an idle current (bias) of around 30mA, it might be fair to presume that they would also be similarly happy at the same levels in the Luxman. Once the unit is up to operating temperature, a reasonable goal would be to attempt to maintain 20-25mV across the resistors, thus indicating 30-38mA idle current.
It would seem more appropriate to connect a millvolt meter across the emitter ends of R120 and R121 to monitor voltage drop through the total 0.66Ω stack, then calculate current. Given that the outputs are identical to those in a Pioneer SX-750, and those seem to work well with an idle current (bias) of around 30mA, it might be fair to presume that they would also be similarly happy at the same levels in the Luxman. Once the unit is up to operating temperature, a reasonable goal would be to attempt to maintain 20-25mV across the resistors, thus indicating 30-38mA idle current.
Thanks I will look at that. I really didn’t want to cut or remove the jumpers. This unit is so pristine, it looks like it was never used. Never seen one this clean and untouched.
I am getting a weird reading across the two ceramic resistors of 0.mv? They are marked .33ohmk
It won’t come out of protection with the jumpers cut.
I changed the fuse in my meter and now it comes out of protection. Boom, all good.
Good luck with your R-1050. It looks like its been well taken care of.
I bought mine in 2009 from a guy who had stored the receiver in his basement for about 30 years after he bought it new. The receiver wasn't pristine, but it wasn't far from it.
A while ago, Blue Shadow recapped it. It is my best amp, hands down.
I bought mine in 2009 from a guy who had stored the receiver in his basement for about 30 years after he bought it new. The receiver wasn't pristine, but it wasn't far from it.
A while ago, Blue Shadow recapped it. It is my best amp, hands down.