Home » Audio » Silicon Valley » Marantz SR-640 SR640 Idle current
Marantz SR-640 SR640 Idle current [message #8003] Sat, 30 August 2008 22:47 Go to next message
vinyltocdr@msn.com is currently offline  vinyltocdr@msn.com
Messages: 14
Registered: May 2009
Chancellor
hello,

i just got done restoring a Marantz SR-640. on the amp board there is a idle current adjustment for each channel (along with a dc offset adjustment).

does anyone have a service manual or know where to put the meter probes and what mA to set the idle current to for the outputs ?

if anyone could tell me this information, it would be greately appreciated.

thanks for any help.

Steve

Re: Marantz SR-640 SR640 Idle current [message #8004 is a reply to message #8003] Tue, 02 September 2008 13:27 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

Have you tried StereoManuals.com?

My gut feeling is if Class AB I would want a small amount of quiescent current, enough that the transistors were biased on but just. No need for current flow to be any higher than necessary to get the transistors biased on.

If Class A, I would want the quiescent current to be biased at the halfway point, but that's the tricky part. The midpoint would be set not only by the current capacity of the output devices but also by the voltage rails oon the power supply. Which ever comes first is the limit, and the halfway point should be set by the limit.


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