C226 was indeed faulty
Cviller,
You were right again. I removed the C226 1 micorofarad electrolytic capacitor and tested it with my ESR meter (first time I have ever used it since I made the kit) and it is faulty. Problem is that it is 11.30 pm here and I went through my vast collection of electrolytic capacitors and couldn't find a 100 V rated 1 microfarad elecrolytic cap. I even took apart two video recorders looking for the part.I temporarily soldered in a 50 volt one.
I replaced the two power amp boards and retested the voltages.
On the annode end of D211 the voltage has now gone from -29V to -42V but does it need to be something else?
I'll send photos later (let me know if you want certain views).
Oh yes, protection led still on and protection relay still does not click.
Cviller,
You were right again. I removed the C226 1 micorofarad electrolytic capacitor and tested it with my ESR meter (first time I have ever used it since I made the kit) and it is faulty. Problem is that it is 11.30 pm here and I went through my vast collection of electrolytic capacitors and couldn't find a 100 V rated 1 microfarad elecrolytic cap. I even took apart two video recorders looking for the part.I temporarily soldered in a 50 volt one.
I replaced the two power amp boards and retested the voltages.
On the annode end of D211 the voltage has now gone from -29V to -42V but does it need to be something else?
I'll send photos later (let me know if you want certain views).
Oh yes, protection led still on and protection relay still does not click.
Me too!
Glad that I should think to google this issue and find you guys talking about it very recently - hope you don't mind if I join in!
I have two 319s (wanted to see what they did when bridged!) and both of them are nippy with their protect circuits. There's got to be an inherent design flaw, right? One amp is generally alright if permanently left on - will have a tantrum if switched off (wasn't me...) but has always recovered thus far. The other amp has been boxed for a while (bridging was a bit much!) and when recently shown daylight failed to come out of protection mode over a number of hours.
My question to you chaps is this: given I haven't the slightest knowledge of electronics beyond lining up a three-pinned plug to the socket in the wall, what to do?! I like reading all of what you've said so far, makes me value my working amp even more, but I don't understand a word of it! I love these amps and would dearly like to revive no.2 - can I just remove the protection circuit relay and hard-wire it?! Am sure it's just messing around...
Sincerely,
A Philistine.
Glad that I should think to google this issue and find you guys talking about it very recently - hope you don't mind if I join in!
I have two 319s (wanted to see what they did when bridged!) and both of them are nippy with their protect circuits. There's got to be an inherent design flaw, right? One amp is generally alright if permanently left on - will have a tantrum if switched off (wasn't me...) but has always recovered thus far. The other amp has been boxed for a while (bridging was a bit much!) and when recently shown daylight failed to come out of protection mode over a number of hours.
My question to you chaps is this: given I haven't the slightest knowledge of electronics beyond lining up a three-pinned plug to the socket in the wall, what to do?! I like reading all of what you've said so far, makes me value my working amp even more, but I don't understand a word of it! I love these amps and would dearly like to revive no.2 - can I just remove the protection circuit relay and hard-wire it?! Am sure it's just messing around...
Sincerely,
A Philistine.
Hi thinksoutloud ,
you are lucky to be able to own two NAD 319s. Unfortunately, I think that there is some design fault that many NAD 319 owners are experiencing. Searching the net seems to bring the same fault where the protect LED stays on and hence the unit does not work. I would not advise you to fool around inside the amp as the voltages are so high.The protection circuit could be bypassed but not by a simple join. You would have to dismantle the whole amp to get to the protection IC but even then it would not be advisable to bypass an important part of the design of this amp.
A note to Cviller:
I did a bad thing and hooked an EZ hook probe onto the annode of D211 BUT the probe tip hit the heatsink of the adjacent transistor (Q201)and fried something.The probe was the positive end of a CRO lead with the negative end connected to earth. Now I am further behind in the quest to fix this amp. Can you tell me what components to start removing to now fix the power supply?
you are lucky to be able to own two NAD 319s. Unfortunately, I think that there is some design fault that many NAD 319 owners are experiencing. Searching the net seems to bring the same fault where the protect LED stays on and hence the unit does not work. I would not advise you to fool around inside the amp as the voltages are so high.The protection circuit could be bypassed but not by a simple join. You would have to dismantle the whole amp to get to the protection IC but even then it would not be advisable to bypass an important part of the design of this amp.
A note to Cviller:
I did a bad thing and hooked an EZ hook probe onto the annode of D211 BUT the probe tip hit the heatsink of the adjacent transistor (Q201)and fried something.The probe was the positive end of a CRO lead with the negative end connected to earth. Now I am further behind in the quest to fix this amp. Can you tell me what components to start removing to now fix the power supply?
One step forward and two steps back...
Without any voltages to work from it is difficult to guess which components are affected. I would guess one of the fusible resitors have triggered, these are R205 and R203. The voltage on these should be around 110V if I remember correctly - it has been a while since I worked on the thingie.
One thing bugs me though. When you wrote your voltages on the protection ic, you measured pin 6 to 0V, which means the coil of the protection relay should be conducting and hence get out of protection mode. You really need to go through the path all the way from pin 6 to supply to find where something is fishy. Have you checked that the relay even works?
Without any voltages to work from it is difficult to guess which components are affected. I would guess one of the fusible resitors have triggered, these are R205 and R203. The voltage on these should be around 110V if I remember correctly - it has been a while since I worked on the thingie.
One thing bugs me though. When you wrote your voltages on the protection ic, you measured pin 6 to 0V, which means the coil of the protection relay should be conducting and hence get out of protection mode. You really need to go through the path all the way from pin 6 to supply to find where something is fishy. Have you checked that the relay even works?
I will be guided by you. I will remove the relay to check it if you want .Or can I test it another way?I know that teh second relay now does not click.(remember there are 3 relays.One clicks when power is applied then another clicks and then the third (protect) does not click.
Do I remove the fusible resistors to check them?
I hope it was only one step back??
Many thanks for your replies.
Do I remove the fusible resistors to check them?
I hope it was only one step back??
Many thanks for your replies.
Thanks for that information. Since I last left off, I lost interest in the amp and it has been sitting on my work bench where I left off last time. As you may have read, I am two steps back from where I started so cahnging those components will only succeed if I can fix where I shorted the heatsink last.Really glad that this thread has picked up again as I have a pair of NAD 319s - one is currently operational, and the other has been standing in the naughty corner for quite some time.
Eds HiFi, I'd be very interested to know how to go about effecting a repair - whilst I have to admit to not even owning a soldering iron, I'm not an idiot and would love to know if this is something the electronics virgin could sort.
Much obliged.
Eds HiFi, I'd be very interested to know how to go about effecting a repair - whilst I have to admit to not even owning a soldering iron, I'm not an idiot and would love to know if this is something the electronics virgin could sort.
Much obliged.
thinksoutloud, I'm afraid you meet quite the challenge, if you have never used a soldering iron. The nad circuit boards are notorious for being of low quality. The tracks breaks of easily, so eventually, after a lot of debugging, I had to replace the whole pcb. Frankly, the whole operation was not really worth it, but I learned a lot...
Getting closer to a working 319!
Hello ,
Just giving you an up date on the amplifier repair. It became way out of my league so I got some professional help last night. It seems that there may be a fault in the actual design so that C226 dries out and fails and this blows the D211 which allows massive voltage to the TA7317 and this blows.This is the protection chip and is hooked to the pin 2 of J107 connector and this causes the fault in right channel.
Just awaiting new TA7317 and hopefully all will be well. Oh yes 4 blown transisitors were located (I assume these were to do with other shorts while fault finding the amp).
Hello ,
Just giving you an up date on the amplifier repair. It became way out of my league so I got some professional help last night. It seems that there may be a fault in the actual design so that C226 dries out and fails and this blows the D211 which allows massive voltage to the TA7317 and this blows.This is the protection chip and is hooked to the pin 2 of J107 connector and this causes the fault in right channel.
Just awaiting new TA7317 and hopefully all will be well. Oh yes 4 blown transisitors were located (I assume these were to do with other shorts while fault finding the amp).
Got one of these collecting dust, when I turn it on the yellow light above the power buttom don`t change. Cant get it out of standby, no protection lights or nothing. Output transistors measure fine and so do the 4 diodes located on the input board. The relay clicks when I push the buttom but then there`s nothing. What could be the cause?
My 2 cents
Full NAD 317 schemetics can be found at
NAD 317 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
I'm going to try to replace D657 and D658, these are zener diodes 1.3W 16V, according to the schematics. As the service note states, mount them away from the board (which is seriously blackened here).
I could not find D659 and D660, they do not appear in the schematics, but are mentioned in the note.
I'll report my results once i'm done.
Greetings,
Jan Wilmans
Full NAD 317 schemetics can be found at
NAD 317 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
I'm going to try to replace D657 and D658, these are zener diodes 1.3W 16V, according to the schematics. As the service note states, mount them away from the board (which is seriously blackened here).
I could not find D659 and D660, they do not appear in the schematics, but are mentioned in the note.
I'll report my results once i'm done.
Greetings,
Jan Wilmans
I hope everyone here are still using the Forum. I have a NAD 317 Working for me for more than 7 years until lately. About a month now i had terrible loud static in my left channel and the Amp went on protect then after some minutes goes normal and plays ok until today. I got back from work and turn it on to listen to some music and it refuses to leave protect mode then again loud static for not even a second and again protect, that happened about 3 times i turned off and wait I havent got smoke or burned smell so i turn it on again but left channel was dead. Anyway, I open it to clean it from dust, disconnected everything, and also i wanted to have a closer look if something was burned but it was not, Cleaned and ready got everything back but still nothing on the left channel after an hour or maybe more i try 1 last time and it works! And now again the same... I know that 317 is the same with 319 thats why i'm asking. In the tests i made was to see if the problem was in pre-amp or in the amp so i got signal from the preamp but in left channel of the main the signal never reaches the circuit. Any idea what to look for? Thanks and Greetings from Greece!
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