Hi Everyone. I have here a NAD C325BEE amplifier which will not power and I am a little stuck.
Service Manual:
https://elektrotanya.com/nad_c325bee-sm.pdf/download.htmlIt was dropped off to me with the report being that it was in use, then started distorting and crackling, then it switched off and had an amber light and would not come back on.
So. I firstly found an issue where the main capacitors for the +46/-46 DC rail were bulging (C517 and C 518) and there was +39V and 0V respectively. As reported the amplifier had an amber power light but would not turn on.
I have replaced these now and I am getting +40V / -40V, which is still a bit low...
Not sure here..... But progress...
I also replaced C523 and C524 as their ESR was pretty high. These are for the +37/-37V rails which measure just fine.
It is my belief these capacitors failed / were in the process of failing as they are exactly next to the main heat-sink... a quick search shows this is a common failure in this model.
So that being sorted (I think) I now have the issue where there is no power light at all. Not even amber. And the amplifier won't respond to the power button.
The service manual check sheet (Page 24) says to check the 5V supply circuit on the power board. However there is nothing labelled 5V at all on the power board schematic. I am assuming this would be the pin labelled "TRIG" ?? Confused here...
Power supply schematic on page 19 of the SM for those playing along.
I have attached a copy of this with my current readings written on it.
All the bits in green I am sure are good.
All the red bits are where I am confused.
The TRIG pin is at 0V
The AC DET pin is at 5V AC and -25V DC
The I-V pin is at 0V
What are these ping exactly. I am not sure.??
So my questions are, firstly what should TRIG, AC DET, and I-V be measuring?
And also why would the +46 and - 46V rails only measuring +40 and -40?
Can anyone make any suggestions here?