This amp has an intermittent crackling problem before the volume control. (Quiet when vol. turned down)
Any suggestions ?
Thanks,
R.
Any suggestions ?
Thanks,
R.
Sorry it's been so long getting back to this but I just had to get on with other things.
Now, I have narrowed the severe crackling to the tuner board where it's very "touchy" around the LA3401 which I think is the MPX IC. During the episodes of crackling, the stereo lamp brightness flickers slightly, - but it does not flicker on & off. I don't know whether it's a dry joint or one of the IC's as it is quite sensitive around the whole area of the LA3401 & the LA1265. I have replaced one of the electro's - (C123) & resoldered a few joints around the area & when turned back on, I thought it was much better until I tried the gentle tap test & off it went again.
The sensitivity is such that dropping a pencil just 1cm above the IC's or gently tapping around the board or on the electro's will set it off. I've also inspected the joints through an 8X magnifier but can't see anything suspicious.
Has anyone had experience with noisy IC's with these units? - somehow I doubt it, & those IC's look pretty difficult to replace as they have more pins & a finer pitch than usual.
Years ago I re-call that NAD did have a dry joint problem so I wonder if this is from that vintage. The boards are made by Tatung going by the marks.
Any suggestions appreciated.
R.
Now, I have narrowed the severe crackling to the tuner board where it's very "touchy" around the LA3401 which I think is the MPX IC. During the episodes of crackling, the stereo lamp brightness flickers slightly, - but it does not flicker on & off. I don't know whether it's a dry joint or one of the IC's as it is quite sensitive around the whole area of the LA3401 & the LA1265. I have replaced one of the electro's - (C123) & resoldered a few joints around the area & when turned back on, I thought it was much better until I tried the gentle tap test & off it went again.
The sensitivity is such that dropping a pencil just 1cm above the IC's or gently tapping around the board or on the electro's will set it off. I've also inspected the joints through an 8X magnifier but can't see anything suspicious.
Has anyone had experience with noisy IC's with these units? - somehow I doubt it, & those IC's look pretty difficult to replace as they have more pins & a finer pitch than usual.
Years ago I re-call that NAD did have a dry joint problem so I wonder if this is from that vintage. The boards are made by Tatung going by the marks.
Any suggestions appreciated.
R.