Marantz 2230 emitter resistors

[yo00]

the 0.24 ohms p750 board resitors value are critical? can i use 0.22 or 0.27 both 5% instead?
can be carbon film or must be cement?

any comments will be really appreciated.

best regards.

Pio

 

[rBuckner]

I would think that 0.22 ohms would be close enough as it's 8.3% lower resistance. Maybe set the idle current adjustment's voltage a bit lower than it would otherwise be. Like if it's 10mV set it at about 9mV. Check the "sticky" service manual thread at the top of the forum for any known mistakes on the 2230 manual.

 

[MoMo64]

I would think that 0.22 ohms would be close enough as it's 8.3% lower resistance. Maybe set the idle current adjustment's voltage a bit lower than it would otherwise be. Like if it's 10mV set it at about 9mV. Check the "sticky" service manual thread at the top of the forum for any known mistakes on the 2230 manual.

I've been using them in my Marantz model twenty five (0.22 Ω 5W 5% the closest value I could find here) and is working wonderfully.

Greeting's

 

[rBuckner]

Thanks MoMo and welcome to AK!

 

[yo00]

I would think that 0.22 ohms would be close enough as it's 8.3% lower resistance. Maybe set the idle current adjustment's voltage a bit lower than it would otherwise be. Like if it's 10mV set it at about 9mV. Check the "sticky" service manual thread at the top of the forum for any known mistakes on the 2230 manual.

that is interesting rBuckner, but i think no matter the resistor value is, in order that the trimpot adjust range can set the right value in mv as the service manual indicates.

maybe i am wrong, hope somebody can chime with more info.

best regards.

Pio

 

[Lavane]

I used .25's in a 1060, (2230 - the tuner). It biased up just fine.

 

[catrafter]

You are measuring a voltage across a resistance to determine the current flow. If you change the resistance and set the voltage the same, then the current changes.
Ohm's Law is your friend.
10mV across both 0.24Ω resistors equals 0.010V/0.48Ω= 20.8mA of idle current.
10mV across both 0.22Ω resistors equals 0.010V/0.44Ω= 22.7mA of idle current.

Probably not enough difference to worry about, but Randy is correct, 9mV would make the current just about perfect.
9mV across both 0.22Ω resistors equals 0.009V/0.44Ω= 20.4mA of idle current.

Tom

 

[rBuckner]

Thanks Tom! I meant to get back to this and forgot. That's exactly what I was thinking though. The 9mV was just an educated guess!

 

[yo00]

Thank you both Tom and rBuckner!

best regards.

Pio

 

[catrafter]

Thanks Tom! I meant to get back to this and forgot. That's exactly what I was thinking though. The 9mV was just an educated guess!

I'm betting it was a very educated guess!

Tom