Hello.
Nad C546BEE CD player.
No power,no standby led.
All fuses OK.
What voltage or components I need control, service manual not clear....
NAD C 546BEE SERVICE MANUAL Pdf Download | ManualsLib
Thank you.
Nad C546BEE CD player.
No power,no standby led.
All fuses OK.
What voltage or components I need control, service manual not clear....
NAD C 546BEE SERVICE MANUAL Pdf Download | ManualsLib
Thank you.
Check and see if the mains transformer has a built in thermal fuse. If the primary reads open circuit then it probably has.
It looks a bit more complex than I first thought.
There is an SMPS used to provide the standby supplies and this also powers a relay to switch power to the mains transformer.
I would begin by checking if the 5 volt supply from the SMPS is present.
Be aware that there are high voltage present on the primary side of the SMPS transformer and the associated drive circuitry.
There is an SMPS used to provide the standby supplies and this also powers a relay to switch power to the mains transformer.
I would begin by checking if the 5 volt supply from the SMPS is present.
Be aware that there are high voltage present on the primary side of the SMPS transformer and the associated drive circuitry.
Attachments
I think that diod d108 on my PCB is not original....
D107 and D108 are the same diodos,but on my PCB D108 is biggest and black....
D107 and D108 are the same diodos,but on my PCB D108 is biggest and black....
Open the C546BEE service manual in PDF reader. Type Ctrl-F and a search window will open. Search for U3 and you will find it labeled 74HC86 on the schematic. Search for U102 and it is TL431.
Also if you search D108 notice that the schematic and parts list conflict. Schematic says UF4006 while parts list says 60V 2A Schottky. Looking at the circuit, I believe the parts list is correct and the schematic is wrong. So D107 and D108 should not be the same.
Also if you search D108 notice that the schematic and parts list conflict. Schematic says UF4006 while parts list says 60V 2A Schottky. Looking at the circuit, I believe the parts list is correct and the schematic is wrong. So D107 and D108 should not be the same.
Last edited:
Ok,thank you.
I think the reparator replaced D108 with UF4006...
and because of that U3 and U102 burnt....
It's trooth or not?
I think the reparator replaced D108 with UF4006...
and because of that U3 and U102 burnt....
It's trooth or not?
D108 needs to be a high speed device, however a UF4006 looks to be correct as these are ultra fast and bear no connection to the 1N4006 series.
If the TL431 really is burned then that is bad news because it implies there could be other damage with the circuitry that the 5 volt rail supplies.
Previous repairer?
So this player has a hidden history...
If the TL431 really is burned then that is bad news because it implies there could be other damage with the circuitry that the 5 volt rail supplies.
Previous repairer?
So this player has a hidden history...
Replacing D108 with UF4006 would not cause U3 or U102 to be damaged. I still think NAD intended D108 to be a Schottky diode although a UF4006 might work. The UF4006 is an 800 volt diode and it isn't NAD's way to use a very high voltage part in a 5 volt circuit.
You seem to have major problems with the unit if U3 and U102 are visibly burned up. The problem likely started in the CPU_5V power supply which does feed power to U3 among many other parts. I would expect there might be quite a bit of damage to parts powered by CPU_5V. Repairing this unit may not be practical.
You seem to have major problems with the unit if U3 and U102 are visibly burned up. The problem likely started in the CPU_5V power supply which does feed power to U3 among many other parts. I would expect there might be quite a bit of damage to parts powered by CPU_5V. Repairing this unit may not be practical.
Ok thank you.
I desoldered the diode D8.He is dead also.
Tell me please what components response for
What components I need control also for CPU_5v
I desoldered the diode D8.He is dead also.
Tell me please what components response for
What components I need control also for CPU_5v
D108 would be a 'normal' type of failure mode that would be expected. You must replace it with a suitable high speed device.
If you have any old SMPS lying around then just use one of the secondary rectifiers from that. Do not use an ordinary diode.
If you have any old SMPS lying around then just use one of the secondary rectifiers from that. Do not use an ordinary diode.
It is OK as long as it is a UF version and not a 1N version.
The 4007 is 1000v rated, the 4006 is 800v
DATA SHEET UF4007
The 4007 is 1000v rated, the 4006 is 800v
DATA SHEET UF4007
The usual cause for failure of SMPS is deteriorated caps as these lead a hard life in this application. All the electrolytics related to the SMPS are suspect.
It is very common to find a chain of parts that have failed once a problem occurs.
If U101 reads short circuit between pin 5 and pin 8 then it is definitely failed.
If it does not read short then it may or may not be faulty.
If the 74HC86 is burnt up then I think the player is beyond any sort of economic repair.
It is very common to find a chain of parts that have failed once a problem occurs.
If U101 reads short circuit between pin 5 and pin 8 then it is definitely failed.
If it does not read short then it may or may not be faulty.
If the 74HC86 is burnt up then I think the player is beyond any sort of economic repair.