Hi,
Long time reader, first time poster here ; )
I acquired a NAD T752 A/V receiver running firmware V1.22 A7 for next to nothing. I know these NAD units have a reputation for poor quality and associated problems and mine certainly has a few issues. Regardless, being somewhat competent with a soldering iron, multi meter and armed with a copy of the workshop manual for the T752, I thought it might be a good opportunity to try and ‘cut my teeth’ on some DIY home audio repair.
While I have researched the T752 on the internet extensively, there does not appear to be any good information available on how to address some of the more frequently encountered issues / problems other than to “Re-flow the solder joints on the boards.”
I was hoping that some users to this forum may have experience with NAD T752 repair and be able to offer me some advice on where to look / start to address the following issues:
1) Loud speaker thump through speakers when the unit is turned off at main power button. Not evident when switching between ON and Standby.
2) On initial startup, a loud audible hiss through speakers for 30-60 seconds is evident until warmed up. After warm up a low audible hiss is still there but after research on the this issue it appears that this is an artifact of the integrated pre-amp in the unit. If the pre-amp binding links are removed from the back of the unit the hiss is non-existant.
3) Accompanying the audio hiss is a ticking sound with a frequency of approximately ½ a second. It should be noted that at playing volumes this sound and hiss described above are not audible.
4) Video and on screen display through Component AV flickers. There is also a line that moves itself up the display once every approximate 4 seconds. The quality of the vide improves after a while, but the underlying deficiencies are still there.
Finally, does anyone know what the last version of firmware was that NAD released for the T572 and if I could obtain this as a SW file to burn my own Ali M6759 A1 EEPROMS?
Regards,
Mike
Long time reader, first time poster here ; )
I acquired a NAD T752 A/V receiver running firmware V1.22 A7 for next to nothing. I know these NAD units have a reputation for poor quality and associated problems and mine certainly has a few issues. Regardless, being somewhat competent with a soldering iron, multi meter and armed with a copy of the workshop manual for the T752, I thought it might be a good opportunity to try and ‘cut my teeth’ on some DIY home audio repair.
While I have researched the T752 on the internet extensively, there does not appear to be any good information available on how to address some of the more frequently encountered issues / problems other than to “Re-flow the solder joints on the boards.”
I was hoping that some users to this forum may have experience with NAD T752 repair and be able to offer me some advice on where to look / start to address the following issues:
1) Loud speaker thump through speakers when the unit is turned off at main power button. Not evident when switching between ON and Standby.
2) On initial startup, a loud audible hiss through speakers for 30-60 seconds is evident until warmed up. After warm up a low audible hiss is still there but after research on the this issue it appears that this is an artifact of the integrated pre-amp in the unit. If the pre-amp binding links are removed from the back of the unit the hiss is non-existant.
3) Accompanying the audio hiss is a ticking sound with a frequency of approximately ½ a second. It should be noted that at playing volumes this sound and hiss described above are not audible.
4) Video and on screen display through Component AV flickers. There is also a line that moves itself up the display once every approximate 4 seconds. The quality of the vide improves after a while, but the underlying deficiencies are still there.
Finally, does anyone know what the last version of firmware was that NAD released for the T572 and if I could obtain this as a SW file to burn my own Ali M6759 A1 EEPROMS?
Regards,
Mike
Unfortunately I think your on to a loser with this one. Although I've zero experience of the NAD the problems sound typical.
1. The thump may be "normal" particularly if there are no speaker relays and time delay. That it doesn't do it when coming in and out of standby is perhaps typical of the design and its intended market and use... in other words left plugged in 24/7 there isn't an issue.
2. Hiss that reduces over a short time seems an odd symptom but again may be typical. There is son much signal processing and switching in these kind of AV amps that again, it may be typical.
3. The "ticking" if regular can only be some kind of digital breakthrough from somewhere... and as I type, I threw it into Google and saw this,
NAD T752 full of bugs | AVForums.com - UK Online
4. Any line moving up or down a video image is usually due to "line" or mains frequency modulation as it is a multiple of frame rate.
I don't think you'll ever win on this one... but you got it for next to 'nowt so not all bad.
1. The thump may be "normal" particularly if there are no speaker relays and time delay. That it doesn't do it when coming in and out of standby is perhaps typical of the design and its intended market and use... in other words left plugged in 24/7 there isn't an issue.
2. Hiss that reduces over a short time seems an odd symptom but again may be typical. There is son much signal processing and switching in these kind of AV amps that again, it may be typical.
3. The "ticking" if regular can only be some kind of digital breakthrough from somewhere... and as I type, I threw it into Google and saw this,
NAD T752 full of bugs | AVForums.com - UK Online
4. Any line moving up or down a video image is usually due to "line" or mains frequency modulation as it is a multiple of frame rate.
I don't think you'll ever win on this one... but you got it for next to 'nowt so not all bad.
Thanks for the comments.
At the very least I was hopeing to fix up the static and thump issue. Thought I would throw it out there to get the benifit of teh forum's collective wisdom and see what else I should pre-emptively repair while I have the case open.
As it stands, it is usable, certainly as a Stereo Tuner and even has Souuround Sound A/V amp as I can go direct from my Blu-Ray player to the TV via HDMI and input audio via Toslink between the player and the T752, although I have not tested this yet and audio lag / delay may be a problem.
Cheers,
Isher
At the very least I was hopeing to fix up the static and thump issue. Thought I would throw it out there to get the benifit of teh forum's collective wisdom and see what else I should pre-emptively repair while I have the case open.
As it stands, it is usable, certainly as a Stereo Tuner and even has Souuround Sound A/V amp as I can go direct from my Blu-Ray player to the TV via HDMI and input audio via Toslink between the player and the T752, although I have not tested this yet and audio lag / delay may be a problem.
Cheers,
Isher
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