Amp is working
Re-instated 18 ohm emitter resistor, re-adjusted BIAS Amplifier is working......🙂
Re-instated 18 ohm emitter resistor, re-adjusted BIAS Amplifier is working......🙂
I had 0.33 ohm 3W resistors on hand, and although the value may be a bit on the high side they fitted nicely to the board for emitter ballasts for Q427-430. As I recall various posts on NAD's evolution of their amp circuitry, the inclusion of base and emitter resistors has helped reduce output stage failures due to thermal bias instability.
Yes some later NAD models are showing that resistor.
On the 3240PE specifically which exactly, transistors did you include the ballast ?
On the 3240PE specifically which exactly, transistors did you include the ballast ?
Q427-430 - each of the low-voltage output stage complementary pairs that have the 3R3 base resistor. As I recall, the pcb has component pads for this part, with just links populating the pcb. A 0.25ohm 2W may be more appropriate if ordering in parts, but physical size could be an issue, so 5W parts are likely to be too large, and the resistors would be mounted vertically.