themarkster
New Member
Hello all,
This is my first post to this forum so I hope I'm doing this in the right place. I recently acquired a NAD 2400 PE, but I soon found it is in need of some repair. I'm knowledgeable with electronics, but I need some help trouble shooting.
When I demoed the amplifier, everything seemed to be in working condition, but when I was playing with it at home, I noticed some sounds would cause a crackling sound. It'd take a sufficient volume to cause this, and once the crackling sound occurred, the actual frequency response of the amplifier would actually change. I was measuring the amplifier with a UMIK-1, and I'd get a good bass response, but it'd start crackling, and the bass response would degrade. Once it starts crackling, it'll continue crackling even at lower volume. I'm able to "reset" the amplifier by toggling "speaker A" on the front of the unit. I'm also using the "lab" RCA inputs, which bypasses the gain pots. I also tried spraying to pots at the front with WD40 electrical cleaner to no avail.
I read that the NAD 2400 PE attempts to improve efficiency by using 2 voltage rails. At sufficiently high power, the amplifier would switch to the higher voltage rail for better dynamic power and better efficiency at low power. I believe that this mechanism is related to the symptoms I'm getting, but I'm not sure what would cause this problem...
I hope I've provided enough information. Let me know if you have any other questions.
Thanks!
This is my first post to this forum so I hope I'm doing this in the right place. I recently acquired a NAD 2400 PE, but I soon found it is in need of some repair. I'm knowledgeable with electronics, but I need some help trouble shooting.
When I demoed the amplifier, everything seemed to be in working condition, but when I was playing with it at home, I noticed some sounds would cause a crackling sound. It'd take a sufficient volume to cause this, and once the crackling sound occurred, the actual frequency response of the amplifier would actually change. I was measuring the amplifier with a UMIK-1, and I'd get a good bass response, but it'd start crackling, and the bass response would degrade. Once it starts crackling, it'll continue crackling even at lower volume. I'm able to "reset" the amplifier by toggling "speaker A" on the front of the unit. I'm also using the "lab" RCA inputs, which bypasses the gain pots. I also tried spraying to pots at the front with WD40 electrical cleaner to no avail.
I read that the NAD 2400 PE attempts to improve efficiency by using 2 voltage rails. At sufficiently high power, the amplifier would switch to the higher voltage rail for better dynamic power and better efficiency at low power. I believe that this mechanism is related to the symptoms I'm getting, but I'm not sure what would cause this problem...
I hope I've provided enough information. Let me know if you have any other questions.
Thanks!
