Hi
I have an old nad 319 amplifier, which unfortunately is completely screwed up. The protect circuit would not turn off. In the beginning, it was only the relay that messed up the signal, but when I got that fixed, the voltage wouldn't drop on the TA7317 (protection circuit). After days of soldering measuring and burning components, I have come to the conclusion that I need a new psu-pcb. The only thing keeping this pcb together is the soldering mask. There is a +/-67V and a +/-60 V on the board. The 60V, which supplies the emitter-followers appears to be very stable, but the 67V running the protect circuit and signal amplification is very unreliable. This is the bottom view of the pcb:
(I have added some resistors to discharge the capacitors, while trying to fix it).
The question is: Do you think I should try to make an exact copy of the old layout or should I just make sure the connectors are placed correctly?
Before I start my pcb program - has anyone else done this before? The pcb is the same as the one in nad 317.
Regards
Christian
I have an old nad 319 amplifier, which unfortunately is completely screwed up. The protect circuit would not turn off. In the beginning, it was only the relay that messed up the signal, but when I got that fixed, the voltage wouldn't drop on the TA7317 (protection circuit). After days of soldering measuring and burning components, I have come to the conclusion that I need a new psu-pcb. The only thing keeping this pcb together is the soldering mask. There is a +/-67V and a +/-60 V on the board. The 60V, which supplies the emitter-followers appears to be very stable, but the 67V running the protect circuit and signal amplification is very unreliable. This is the bottom view of the pcb:
An externally hosted image should be here but it was not working when we last tested it.
(I have added some resistors to discharge the capacitors, while trying to fix it).
The question is: Do you think I should try to make an exact copy of the old layout or should I just make sure the connectors are placed correctly?
Before I start my pcb program - has anyone else done this before? The pcb is the same as the one in nad 317.
Regards
Christian
I think it is worth rebuilding, because I really liked the sound when it worked.
I know there are many in here that don't like nad, but besides the bad pcb quality, I think it is a matter of taste and I think the sound is very good compared to the price.
I have another question. In the 67psu, there are some 100 Ohm fusible 1W resistors that died during repair.
The part of the schematic with these resistors can be seen here:
Part of psu schematic
I can't find the components in Denmark. Do you guys think it will safe to use regular power resistors?
Some of the resistors in the amp are "flame proof". Are most power resistors not flame proof?
Christian
I know there are many in here that don't like nad, but besides the bad pcb quality, I think it is a matter of taste and I think the sound is very good compared to the price.
I have another question. In the 67psu, there are some 100 Ohm fusible 1W resistors that died during repair.
The part of the schematic with these resistors can be seen here:
Part of psu schematic
I can't find the components in Denmark. Do you guys think it will safe to use regular power resistors?
Some of the resistors in the amp are "flame proof". Are most power resistors not flame proof?
Christian
cviller said:
Hi Christian
If you can't find "flame proof" resistors , change the R203 FP resistor for the place of the R205 resistor and use a regular resistor in the place of R203 , because this last one , is not in a so critical position , as R205 , in case of a short in the + 67 Volt rail.
Cheers
Layout DONE!!! 
I have finished the all the layout work. I might change something before i do the actual pcb, but it won't be much. It took me forever, because I had to draw schematics and footprints also.
Tube dude: Thank you very much for providing a solution. It was not flame proof, but fusible, but the idea of using ordinary power transistors for the none critical parts should stil be valid.
I really hope I can make it work now. Someone interested in the pcb.ps when it's working?
I have finished the all the layout work. I might change something before i do the actual pcb, but it won't be much. It took me forever, because I had to draw schematics and footprints also.
Tube dude: Thank you very much for providing a solution. It was not flame proof, but fusible, but the idea of using ordinary power transistors for the none critical parts should stil be valid.
I really hope I can make it work now. Someone interested in the pcb.ps when it's working?
I have placed the pdf ps files here:
PCB and schematics
(The files won't be there forever, but mail me if they are gone and you need them)
I recommend using the ps files if you have access to a postscript printer, but the pdfs should also work.
Use of this layout is at your own risk. I cannot be held liable for any damages to humans,property,animals etc., caused by using the layout. Nadelectronics holds the copyright for the schematics and layout structure. This is a reproduction of the psu-pcb and only intended for repair purposes.
The layout does work for me. The sound appears to be like before - no distortion. An important thing to do if you plan to use my layout is to make sure that there are no shorts. I had some shorts I needed to scratch away using a knife, but it might have been because I didn't gave the board enough time in the developer-fluid.
I have made most of the drill holes smaller than they should be to make sure the solder pads would be completely covered with copper, but if you do the pcb drilling your self, you can just look on the original pcb.
My program does not have a symbol for all those shorts on component side, so I have drawn them on the componentside as copper traces. You'll need to print the component side to get those locations. All components and shorts are placed very close to the original, so you can just take one at a time.
I think it is a good idea to start with all the psu stuff for the 5V, +-60 and +-67, and then make sure you have the correct voltages and no smoke.
Remember to discarge the big capacitors before you start soldering!
Why do you need to make a new pcb? Is it because the the solder pads are falling apart?
PCB and schematics
(The files won't be there forever, but mail me if they are gone and you need them)
I recommend using the ps files if you have access to a postscript printer, but the pdfs should also work.
Use of this layout is at your own risk. I cannot be held liable for any damages to humans,property,animals etc., caused by using the layout. Nadelectronics holds the copyright for the schematics and layout structure. This is a reproduction of the psu-pcb and only intended for repair purposes.
The layout does work for me. The sound appears to be like before - no distortion. An important thing to do if you plan to use my layout is to make sure that there are no shorts. I had some shorts I needed to scratch away using a knife, but it might have been because I didn't gave the board enough time in the developer-fluid.
I have made most of the drill holes smaller than they should be to make sure the solder pads would be completely covered with copper, but if you do the pcb drilling your self, you can just look on the original pcb.
My program does not have a symbol for all those shorts on component side, so I have drawn them on the componentside as copper traces. You'll need to print the component side to get those locations. All components and shorts are placed very close to the original, so you can just take one at a time.
I think it is a good idea to start with all the psu stuff for the 5V, +-60 and +-67, and then make sure you have the correct voltages and no smoke.
Remember to discarge the big capacitors before you start soldering!
Why do you need to make a new pcb? Is it because the the solder pads are falling apart?
Exactly - solder pads are falling apart. I had some problems with psu, and while soldering I noticed that the pcb is just a piece of scrap. I'm not yet sure if I'm going to make a new one, but now it would be easy, thanks to you. Now I also know I can use the ps files.
I totally understand that it's all at my own risk. Thanks for the files and advice!
I totally understand that it's all at my own risk. Thanks for the files and advice!
Dear Cviller ,
I have read with interest your NAD 319 activities. I myself have the same amplifier which was repaired at a NAD dealer and it soon died.I took the amp apart and was shocked at how badly it had been repaired!! The main circuit board was so badly wrecked that replacement resistor legs were merely folded over to join to other components. I used acetone to try to clean up excessive (what looks like) flux and attempted to redo the burned out tracks. The protection LED remains lit.
The preamplifier section is fully functional but no signal appears to be coming from the main circuit board. Thus the two amplifier boards are not receiving any signal at all.
I have the use of a signal generator and a CRO but I am not an expert in electronics. I can ask my friend any technical questions as he has a vast knowledge of electronics.
Would I be able to see your diagrams of the new PCB you made please? Do you have a photo of the original PCB?
Do I start looking around the TA7317 for faults?
Thankyou in advance.
I have read with interest your NAD 319 activities. I myself have the same amplifier which was repaired at a NAD dealer and it soon died.I took the amp apart and was shocked at how badly it had been repaired!! The main circuit board was so badly wrecked that replacement resistor legs were merely folded over to join to other components. I used acetone to try to clean up excessive (what looks like) flux and attempted to redo the burned out tracks. The protection LED remains lit.
The preamplifier section is fully functional but no signal appears to be coming from the main circuit board. Thus the two amplifier boards are not receiving any signal at all.
I have the use of a signal generator and a CRO but I am not an expert in electronics. I can ask my friend any technical questions as he has a vast knowledge of electronics.
Would I be able to see your diagrams of the new PCB you made please? Do you have a photo of the original PCB?
Do I start looking around the TA7317 for faults?
Thankyou in advance.
Don't get me started on the pcb build quailty...
I'm currently in mumbai, so I don't have easy access to my files on the NAD. Regarding your question, yes, it is a good idea to check the voltages around ta3717, but be careful, the voltages are high enough to blow components if you short circuit something.
It is very dificult to repair a pcb which is falling apart, and I cant really give you much information on where to start. I spent quite some time fixing the damn thing, but I eventually got it to work nicely. If you post some measurement I might be able to help you.
I'm currently in mumbai, so I don't have easy access to my files on the NAD. Regarding your question, yes, it is a good idea to check the voltages around ta3717, but be careful, the voltages are high enough to blow components if you short circuit something.
It is very dificult to repair a pcb which is falling apart, and I cant really give you much information on where to start. I spent quite some time fixing the damn thing, but I eventually got it to work nicely. If you post some measurement I might be able to help you.
Thanks Cviller,
I think I need to look at the PCB overlay to work out where I am because although I have the circuit diagram, i am having problems seeing where the old tarcks were burned off. i did remove the messy blobs of solder which were all over the place but we cannot assume that teh last repairer placed teh solder joins correctly. The main problem area is in teh vicinity of R213,R212,R211,R216 and caps C221, C220.
i kno wthat all parts of the circuit are related but would problems here affect the protection LED to remain lit?
Would posting a photo of the track side of the board help you at all?You may be able to remember where the tracks used to go but
I know it has been a few years since you fixed your NAD 319.
Are you returning to where your NAD info is located in the near future?
I think I need to look at the PCB overlay to work out where I am because although I have the circuit diagram, i am having problems seeing where the old tarcks were burned off. i did remove the messy blobs of solder which were all over the place but we cannot assume that teh last repairer placed teh solder joins correctly. The main problem area is in teh vicinity of R213,R212,R211,R216 and caps C221, C220.
i kno wthat all parts of the circuit are related but would problems here affect the protection LED to remain lit?
Would posting a photo of the track side of the board help you at all?You may be able to remember where the tracks used to go but
I know it has been a few years since you fixed your NAD 319.
Are you returning to where your NAD info is located in the near future?
You beauty! (as we say in Australia).
My friend the electronics Engineering person had a look at the PSU circuit and explained his version of "how it works". He said that if the transistors Q201 or Q204 or the Zener diodes D208 or D209 did not do their job correctly, the voltage on the power supply could jump from the correct 67 volts to a potential 336 volts which could blow out other things. I still have to check the circuit around the resistors I mentioned in my last email before I power it up.
Anyway, the PCB information and anything related to the 319 would be much appreciated.
Can you also tell me if there are other NAD 319 circuits which describe the other parts of this amplifier?
My email is jyonggee@optusnet.com.au
I'll post on this site how I go with the repair.
My friend the electronics Engineering person had a look at the PSU circuit and explained his version of "how it works". He said that if the transistors Q201 or Q204 or the Zener diodes D208 or D209 did not do their job correctly, the voltage on the power supply could jump from the correct 67 volts to a potential 336 volts which could blow out other things. I still have to check the circuit around the resistors I mentioned in my last email before I power it up.
Anyway, the PCB information and anything related to the 319 would be much appreciated.
Can you also tell me if there are other NAD 319 circuits which describe the other parts of this amplifier?
My email is jyonggee@optusnet.com.au
I'll post on this site how I go with the repair.
NAD 317 Weird fault!
Hello All,
I originally posted this message on the sci.electronics.repair usenet group but still have the fault & hope someone here can help.
I hope someone may help me with fixing this NAD317 integrated
amplifier made in 1997.
The owner reported strange distortion only at low levels of output on
both channels.
Hook up a 'scope & feeding in a 1kHz sine wave shows intermittent high
frequency oscillation distorting the waveform. You can see the traces
on the link below:
http://personales.ya.com/cannet/
My first suspicion is the PSU electrolytic caps (6 off 4700uF 63V & 4
off 220uF 160V), when I tap around them sometimes the fault goes away
if present. Similarly I can sometimes cause the fault by tapping them.
But strangely I can see no sign of the oscillations on the power
supply rails to either pre or power amp (the distortion is present at
the pre amp output). Also strange is that sometimes just passing my
hand over the PSU board can cause or cure the fault. Perhaps this
could be a dry joint also?
Any tips on trouble shooting this are welcome.
Best regards,
Greg.
Hello All,
I originally posted this message on the sci.electronics.repair usenet group but still have the fault & hope someone here can help.
I hope someone may help me with fixing this NAD317 integrated
amplifier made in 1997.
The owner reported strange distortion only at low levels of output on
both channels.
Hook up a 'scope & feeding in a 1kHz sine wave shows intermittent high
frequency oscillation distorting the waveform. You can see the traces
on the link below:
http://personales.ya.com/cannet/
My first suspicion is the PSU electrolytic caps (6 off 4700uF 63V & 4
off 220uF 160V), when I tap around them sometimes the fault goes away
if present. Similarly I can sometimes cause the fault by tapping them.
But strangely I can see no sign of the oscillations on the power
supply rails to either pre or power amp (the distortion is present at
the pre amp output). Also strange is that sometimes just passing my
hand over the PSU board can cause or cure the fault. Perhaps this
could be a dry joint also?
Any tips on trouble shooting this are welcome.
Best regards,
Greg.
Hai there,
My name is Ben and I am attempting to repair a Nad 319.My problem are once the amp is turn and playing music about 10 sec it will restart and about 30 sec and it would shut down and won't turn on. after I disconnect the mains and plug it in again and it do the same thing.
How can i repair this amp I think it got to do something with the PSU board.I need help this amp have a lot of sentimental values
Hope for your reply
My name is Ben and I am attempting to repair a Nad 319.My problem are once the amp is turn and playing music about 10 sec it will restart and about 30 sec and it would shut down and won't turn on. after I disconnect the mains and plug it in again and it do the same thing.
How can i repair this amp I think it got to do something with the PSU board.I need help this amp have a lot of sentimental values
Hope for your reply