Hi,
I think my Njoe Tjoeb 4000 CD player muting relay might be going on the blink - periodically the sound will randomly mute, accompanied by a soft click from the player. The disc keeps spinning/playing. Usually the sound will come back after a couple of seconds (with another soft click from the player), but at least once it has stayed off longer and pausing/unpausing the disc immediately fixed it. Typically once it's done this it will then work perfectly until the player is switched off, it's never gone wrong more than once in a given listening session!
Does this sound like the correct diagnosis? Anyone experienced anything like this? Could anyone recommend a possible remedy - could the muting relay be repaired or replaced? I am not an experienced modder but perhaps at least knowing what the issue is, I might be able to take it to a repair shop? With it being an unusual player I am concerned that a mainstream repair place would not know what to do - if "CD player repair" is even still a commercial possibility these days...
It's such an amazing-sounding player and still works perfectly apart from this issue so hopefully there will be a solution! Many thanks in advance.
Cheers,
Steve
I think my Njoe Tjoeb 4000 CD player muting relay might be going on the blink - periodically the sound will randomly mute, accompanied by a soft click from the player. The disc keeps spinning/playing. Usually the sound will come back after a couple of seconds (with another soft click from the player), but at least once it has stayed off longer and pausing/unpausing the disc immediately fixed it. Typically once it's done this it will then work perfectly until the player is switched off, it's never gone wrong more than once in a given listening session!
Does this sound like the correct diagnosis? Anyone experienced anything like this? Could anyone recommend a possible remedy - could the muting relay be repaired or replaced? I am not an experienced modder but perhaps at least knowing what the issue is, I might be able to take it to a repair shop? With it being an unusual player I am concerned that a mainstream repair place would not know what to do - if "CD player repair" is even still a commercial possibility these days...
It's such an amazing-sounding player and still works perfectly apart from this issue so hopefully there will be a solution! Many thanks in advance.
Cheers,
Steve
Thanks - I suspect it's the "digital" relay that's at fault.
I assume the "big" relay goes on and off with the player, you get a big click with that one. Then when playing/pausing a disc you get a small click - that's the one I hear when the player goes silent on its own. Also pausing/unpausing the disc brings the sound back, probably because it resets the relay? In addition, the sound goes INSTANTLY on and off, if the tube stage was losing power I'd expect a more gradual fade.
The next question is, even if I knew that was the fault, what could I (or a qualified technician) potentially do about it? Presumably it's either the signal that is sent to the relay or the component(s) not quite performing correctly. What could be done in either case? Does anyone have any pictures or information about these components?
It's still such a great-sounding unit, it would be a shame if this annoying fault could not be resolved.
I assume the "big" relay goes on and off with the player, you get a big click with that one. Then when playing/pausing a disc you get a small click - that's the one I hear when the player goes silent on its own. Also pausing/unpausing the disc brings the sound back, probably because it resets the relay? In addition, the sound goes INSTANTLY on and off, if the tube stage was losing power I'd expect a more gradual fade.
The next question is, even if I knew that was the fault, what could I (or a qualified technician) potentially do about it? Presumably it's either the signal that is sent to the relay or the component(s) not quite performing correctly. What could be done in either case? Does anyone have any pictures or information about these components?
It's still such a great-sounding unit, it would be a shame if this annoying fault could not be resolved.
Yeah... that transport, tube analog stage and that power cable.... more than enough to make them sound nice and pleasing 
The KILL signal comes from few places. From the CD mechanism PCB (mounted underneath the mechanism) and from the front panel (8-bit CPU). See Capture.jpg
The service manual for CD4000 is available from few places - I downloaded it from HiFiEngine. If you are not confident (or if you don't have the equipment to test/ capture the fault instance)... take the CD player to a service technician. Hopefully, he'll fix it for you.
The KILL signal comes from few places. From the CD mechanism PCB (mounted underneath the mechanism) and from the front panel (8-bit CPU). See Capture.jpg
The service manual for CD4000 is available from few places - I downloaded it from HiFiEngine. If you are not confident (or if you don't have the equipment to test/ capture the fault instance)... take the CD player to a service technician. Hopefully, he'll fix it for you.
Attachments
Thanks for the diagram, very useful - would the fact that there are 2 "digital" relays but both channels always mute/unmute together indicate that it's the KILL signal that's at fault (rather than the actual relays)?
Then it becomes about which of the other parts is sending the signal in error and why...I do have a spare transport mechanism but am reluctant to replace that as in terms of spinning and reading discs the current one works perfectly.
I almost need the mute relay to engage permanently - I think that would make it easier for a service technician to find and diagnose. At the moment it's so brief and intermittent, it played for 2.5 hours perfectly last night and that's not uncommon.
I know nothing lasts forever but do not look forward to having to find a long-term replacement for such a unique CD player...
Then it becomes about which of the other parts is sending the signal in error and why...I do have a spare transport mechanism but am reluctant to replace that as in terms of spinning and reading discs the current one works perfectly.
I almost need the mute relay to engage permanently - I think that would make it easier for a service technician to find and diagnose. At the moment it's so brief and intermittent, it played for 2.5 hours perfectly last night and that's not uncommon.
I know nothing lasts forever but do not look forward to having to find a long-term replacement for such a unique CD player...
You could download the service manual as explained already. Then have a look at KILL sources (I have also pointed this out already...).
You could monitor & record the KILL signals with a 2-channel oscilloscope (the source of KILL signal is multiple, at least two sources... also mentioned already) with a record function. A cheaper option would be a PicoLog 6 and associated hardware; here you can have many channels of simple monitoring and historical trending (i.e. the record function on cheap).
I still believe that you should take that thing to a capable, sensible electronics engineer/service technician.
It seems that Njoe used his analog board.... so, my statement above about finding someone capable applies in full.
Good luck.
You could monitor & record the KILL signals with a 2-channel oscilloscope (the source of KILL signal is multiple, at least two sources... also mentioned already) with a record function. A cheaper option would be a PicoLog 6 and associated hardware; here you can have many channels of simple monitoring and historical trending (i.e. the record function on cheap).
I still believe that you should take that thing to a capable, sensible electronics engineer/service technician.
It seems that Njoe used his analog board.... so, my statement above about finding someone capable applies in full.
Good luck.
Understood - I wasn't sure how the original CD4000 service manual would help but it makes sense about the KILL signals.
The player randomly muted again for a few seconds last night (had to press Pause and Play to fix it) so the issue is definitely getting worse.
You're right that this is technically out of my league - the information you have provided should come in really useful should I take it to a professional, thanks!
Last question - does anyone know of any good CD player repair outfits in the Nottingham/East Midlands area?
The player randomly muted again for a few seconds last night (had to press Pause and Play to fix it) so the issue is definitely getting worse.
You're right that this is technically out of my league - the information you have provided should come in really useful should I take it to a professional, thanks!
Last question - does anyone know of any good CD player repair outfits in the Nottingham/East Midlands area?