Hi all,
I was wondering if anyone can help me with fixing a very dim VFD display on my NAD 5320? There's lots of information on changing bulbs behind the later NAD's LCD displays but I can't find anything on this problem.
Some parts of the display are brighter than the others. Schematics can be found here.
NAD 5320 Compact Disc Player Manual | HiFi Engine
I'm not very good in reading those.... 😀
I received it not working at all. I changed C601 and C602 but that was easy: they had leaked. Also the voltage regulator was changed. And now it works. Except for the display. All variable resistors are assigned to the Laser and such (I checked that).
I was wondering if anyone can help me with fixing a very dim VFD display on my NAD 5320? There's lots of information on changing bulbs behind the later NAD's LCD displays but I can't find anything on this problem.
Some parts of the display are brighter than the others. Schematics can be found here.
NAD 5320 Compact Disc Player Manual | HiFi Engine
I'm not very good in reading those.... 😀
I received it not working at all. I changed C601 and C602 but that was easy: they had leaked. Also the voltage regulator was changed. And now it works. Except for the display. All variable resistors are assigned to the Laser and such (I checked that).
C603, C604 and C605 would be favourites.
Don't discount a low emission display but the caps should be replaced first. Be careful of the polarity and use only the same values as are fitted.
Don't discount a low emission display but the caps should be replaced first. Be careful of the polarity and use only the same values as are fitted.
I'm glad I asked 🙂 Last question (sorry...) I can't find a 0.4 21.5 V diode. Should I round up or down? So 20 V or 22 V?
If you want to order the diode then go for a 22v part but I would be surprised if they were at fault tbh.
Caps and/or a low emission display are the most common. Also don't forget to clean the VFD itself if possible and also give the inside of the window a polish. They can attract a lot of grime over the years.
Caps and/or a low emission display are the most common. Also don't forget to clean the VFD itself if possible and also give the inside of the window a polish. They can attract a lot of grime over the years.
jacobr, just wondering if you were successful in fixing the dim VFD? I have the identical problem on a NAD 5320 as well. The player works fully but the VFD is quite dim. Caps C601 and C602 are leaking and need to be replaced. I have not done that yet. Did replacing C603, C604, C605 solve the problem? I noted that 12voltvids on Youtube posted his work on a NAD 5325 (identical as 5230 except it has a remote) on his bench in a video entitled "NAD 5325 CD Player 2 faults" and half way through he notes that NAD VFD's are always dim due to using red as the colour. I would think that like and VFD if you increased the voltage you would make it brighter would you not? Of course the one one his bench also had a very dim VFD.
If you take the front panel PCB off the front panel and plug it back in to the main board, you'll probably see that the display is bright (and blue/green). There's a lot of intensity lost in the red filter on the front.
Something to check which I don't think has been mentioned is the value of R707 and R708 (on the display PCB). These vary between 50Hz and 60Hz countries (1Ω for 50Hz and 2Ω for 60Hz).
Oh, BTW, C601 and C602 probably aren't leaking. The brown sludge is a gow-awful glue that NAD and others use to hold bigger caps down.
If you are swapping caps, it's probably a good idea to throw away the non-polar electros and substitute film ones. On mine I kept the same values except for C509 and C510, where I used 4Ω7 50V film).
Something to check which I don't think has been mentioned is the value of R707 and R708 (on the display PCB). These vary between 50Hz and 60Hz countries (1Ω for 50Hz and 2Ω for 60Hz).
Oh, BTW, C601 and C602 probably aren't leaking. The brown sludge is a gow-awful glue that NAD and others use to hold bigger caps down.
If you are swapping caps, it's probably a good idea to throw away the non-polar electros and substitute film ones. On mine I kept the same values except for C509 and C510, where I used 4Ω7 50V film).
Thanks suzyj! That is very useful info. I thought it strange that the caps appeared to be leaking badly but that they did not show the common sign of bulging on the top and also the player still functioned flawlessly.
Are you saying that the "red filter" is simply the red coloured plastic of the display window? If so, presumably replacing it with just a clear plastic would then allow for the display to show as blue/green and be more intense?
Once again, I really appreciate the info. Saved me some time for sure.
Are you saying that the "red filter" is simply the red coloured plastic of the display window? If so, presumably replacing it with just a clear plastic would then allow for the display to show as blue/green and be more intense?
Once again, I really appreciate the info. Saved me some time for sure.