Good morning.
I have a NAD C355bee amplifier, which actually works very well and sounds great.
However, just out of curiosity, since the amplifier is already 15 years old, I tried to measure the Idle current and isc circuit parameters.
In the service manual it refers to a value of 6mV for idle current, however, I measured a value of 8mV (after the amplifier had been on for 20 minutes), in both channels (to be precise 8mV L channel and 8.1mV R channel).
Can these values still be considered normal or do they need calibration as reported in the manual (6mV)?
For the calibration of the ISC circuit I did not understand well how to proceed.
The manual indicates "adjust the pot VR3 to make the DC voltage of the point of TP10 to the same as TP11".
If I measure TP10 (one tip on TP10 and one on ground) I get 56.5mV
If I measure TP11 (one tip on TP11 and one on ground) I get 19.5mV
If I measure TP10 + TP11 (one tip on TP10 and one on TP11) I get 34.7.
I have not touched any potentiometers yet, and before I do (if necessary), I would like to understand..
Thanks very much!
I have a NAD C355bee amplifier, which actually works very well and sounds great.
However, just out of curiosity, since the amplifier is already 15 years old, I tried to measure the Idle current and isc circuit parameters.
In the service manual it refers to a value of 6mV for idle current, however, I measured a value of 8mV (after the amplifier had been on for 20 minutes), in both channels (to be precise 8mV L channel and 8.1mV R channel).
Can these values still be considered normal or do they need calibration as reported in the manual (6mV)?
For the calibration of the ISC circuit I did not understand well how to proceed.
The manual indicates "adjust the pot VR3 to make the DC voltage of the point of TP10 to the same as TP11".
If I measure TP10 (one tip on TP10 and one on ground) I get 56.5mV
If I measure TP11 (one tip on TP11 and one on ground) I get 19.5mV
If I measure TP10 + TP11 (one tip on TP10 and one on TP11) I get 34.7.
I have not touched any potentiometers yet, and before I do (if necessary), I would like to understand..
Thanks very much!
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The procedure you posted doesn’t mention TP10 and 11. Typically, if the don’t explicitly tell you to measure between two points, it’s assumed that you measure against ground.
But the procedure you showed told you to measure between two specific points.
But the procedure you showed told you to measure between two specific points.
Yes, TP10 and TP11 are mentioned in the first photo (last paragraph "Original ISC circuit adjustment: adjust the pot VR3 to make the DC voltage of the point of TP10 to the same of TP11").
Idle current and ISC adjustment are two different procedures.
I think ISC is the protection circuit..
Idle current and ISC adjustment are two different procedures.
I think ISC is the protection circuit..
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