NAD C720BEE (C320BEE) fixed.

Hi.
I am French.
Excuse me if my English is not very good.

I own a NAD C720BEE.
It does not work anymore.
I did not use it for several months.
He was, all the while, in standby mode (amber light).

The breakdown is:
- VACATION SWITCH ON/OFF -> ON => POWER/STANDBY/PROTECTION LED -> AMBER.
- POWER Button -> ON => POWER/STANDBY/PROTECTION LED -> stays AMBER, but i hear, after a few seconds, some clic on some relays.
- The TROUBLESHOOTING GUIDE indicates : CHECK THE 12V POWER SUPPLY CIRCUIT.

I have not +12V, on E-Q413 (J123 (12V)), because i have not +18V.
The +18V is generated from the +37V.

For information, the value of +/- 46V (V+, V-) are +/- 37V. The power supply is, therefore, in degraded mode.

The VFD board is OK.
The Reset (FM + CD) is OK.
The Software version ("FM''+"AM") is V 1.03.

After investigation, R45 (33 Ohms 1/2W) is broken (no +37V on C-Q41)
R45 was broken because C49 is in short circuit.
Becarefull: the schematic indicate : C49 47uF/ 25V, on board it’s a 47uF/50V.


Good luck.

Loubine.
 
Well, my friend, you need to improve a bit your english ::)

Anyway, always check the big caps in the power board. If your amp is 15-20 years old, they can be failing.

A friend of mine repaired mine c320bee, replacing a driver transistor.

I got my fuses blown instantly, that transistor drove all the current in.

I don't know where your problem is, i wish u all the luck