NAD 3020i - /13V on Left Output/

[petehall347]

Re: NAD 3020i - /13V on Left Output/

see what voltage each side of r411
also r447 r449 .
negative voltage is getting lost ..
it could be swamped with positive voltage or simply missing .

[budm]

Re: NAD 3020i - /13V on Left Output/

Schematic here is better : http://p10hifi.net/planet10/TLS/down..._schematic.gif

From power supply i have all correct voltages / -28v,+28v,+43, +28/+32 (4om/8om/ /

On B/E Q415/Q417 I have 12.4V /begin from 6v,...8v, 11v...etc/ -
R453 I have on both side 12.4v
On B/E Q411/413 I have 12.4V
On B/E Q409 I have 12.4V
R445 Both side 12.3v
R451 Both side 12.3v
R439 Both side 12.3v
D405 Both side 12.4v
On B/E Q407 I have 12.4V

When you are saying you have B/E of 12V or what ever, do you have one probe on the Base and another on the Emitter? When we are talking about B/E Voltage reading we referring to the Voltage taking between the two legs (B and E) of the Transistor to verify the Junction Voltage reading, you must clarify what you are are providing in you DATA.

[coojoe_213]

Re: NAD 3020i - /13V on Left Output/

Ok, sorry. My measure are Ground to Base/Emiter. I will measure like you want, this night. Today what i do...
I remove main transistors 2n3055/2mj2930, also Q409 (bd139), also i remove and Q413/Q411. Turn on amp (from 100 watts lamp - no lights) and the problem was same. But when i turn off the amp from AC, after 25-30 min, i have 9-10 volts on left chanell (terminals)

[budm]

Re: NAD 3020i - /13V on Left Output/

I do not know if you understand how Transistor works or not or what to expect as far as the Voltage of the Transistor junction should be. If you use circuit GND as the ref. for your meter, the Voltage reading on the Base and the Voltage reading on the Emitter should not be the same, you should look up how Transistor is biased.