NAD C370 amplifier repair.
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- čas přidán 6. 09. 2024
- Here we track down the cause of the speaker output relays not switching on for a delayed period then switching off with a chattering effect.
Tools I use -
Soldering
Quick 861DW hot air station
Duratech TS-1640 solder iron
Multimeter
RMM760D - can be found under many name badges
Microscope
Luzky Zoom 3.5 - 90x simul-focus single boom stand trinocular stereo microscope
Camera - Lucky Zoom HD 14MP
Oscilloscopes
Siglent SDS 1102CML 100MHz 2CH
Philips PM 3305 35MHz 2CH
Bench supply
Powertech MP-3086 0-30V 3A
TL866II PLUS universal EEPROM programmer
I have fixed a couple of c352, and all the caps in both were bad! Solder joints in hot areas on board needed reflowing. Both now work. These amps seem to have same issues. I used Panasonic caps (FR and FC) mainly.
Great video 👍
Cheers mate!
Great video!
Im in process of repairing one of these beauty's.
Pretty much the same as the one you have there but the glue isnt quite as far gone which may suggest its been used less. Ive sorted the protect board first and put the diode aroumd the backside of the board and fit new caps.
Ive decided to recap the whole amp as there are others that are sat right against heat sinks and have changed colour with heat stress. Can't wait to get it working.
Glad you know what you're doing because you freak me out tapping on everything when it is turned on. :)
This is gonna help everyone whose got one, if not already done :) good stuff!
Speaker B is if your running a second pair of speakers into a different room. I had a similar issue with a crest audio ca9 amp and had to resolder every joint. Great video as usual
Thanks!
No, speaker b is for speakers with bi-wire or for blowing up your speakers. If you have used for sound in other rooms, you buy a multi-room amplifier
I have two of these amps on is still kicking and the other one is protection circuit issue,i tried to fix and it worked for a while but my soldering is poor , i really think that these amps are amazing quality for the money,,poor people like me can listen to a reasonable level of sound quality,, ive listened to some half million pound systems at a sound expo and i think that some people don't know how to be happy with life as they are not a million miles away from the nad gear
I've done many of these. The protection board is a known weak point. I normally just swap all the caps and move the zener from the front to the back of the board - out of the way of the capacitors. In general, all the low value capacitors are dying on all the C370s. Not only in the protection circuit.
Good idea with the diode, will keep in mind for the next one.
hi, just a question, Im having issues with my Nad C350, seems to go into protection mode (red power LED) when pushed past a certain limit (not highly pushed) after the unit has been on for a couple hours. Would this issue most likely be similar? thanks
@@rodneyyuen Quite likely as things warm up etc. Would be worth replacing the caps on it and refreshing all the solder joints anyway. It seems this module becomes a problem on every unit out there.
@@JonnyFix thanks for your advice. Couple of questions if you dont mind? Question 1- Do you feel that the repair like you did on your NAD c370 from fault diagnostics and repairing is a dying art? Quistion 2-does changing components like you did change the sound signature of amp? Thanks again
@@rodneyyuen I think general electronics repair is a dying art. There aren't a lot of big repair businesses that you could say get an apprenticeship with and learn on the job. Most repair shops are single owner-operator. I guess there's university classes that cover electronics still but I don't think they aim for a focus on repair, probably more like understanding for the purpose of designing products. I think the most successful repair people start young, have a deep interest for wanting to know how things work and just messing around with it an learning as you go. I think the best way to make money from repair is niche markets like automotive electronics, medical equipment, musical instruments. General consumer electronics are so cheap now most of it isn't worth the time to repair. As for this job, the protection module has nothing to do with audio reproduction so no it won't change anything about the amp. All it does is watch for a problem at the output and isolate the speakers if there is one. You're welcome!
We have the same issue . Thank you !!
Just found your awesome channel! Cheers from SLC Utah! 😎🤟😸
Although when functioning they sound quite good, NAD’s QC leaves a lot to be improved. Every NAD across my bench has had numerous problems. I’m not a fan of shotgunning components but there’s always a large pile of bad parts when repair is complete.
I have just bought two old NAD amps that works ok, but needs a little attention.
What is the typical issue to look at?
Heat I find is the main problem, they seem to run inordinately hot compared to anything else, although my NAD C350 is class A in the preamp still shouldnt cause too much heat, seems to come from underrated components.
@Tim Lyons I'm going to install a fan on the inside both of them👍 thank you for being so helpful😁
Glad to see you again, very useful vidéo, bravo ! from France
Thank you, glad you enjoyed!
This era of NAD equipment was littered with JH brand capacitors which were absolute junk. Any piece that I've worked on from this era has had most, if not all its caps, go high-ESR and out-of-spec. If you're planning on keeping these pieces long-tern, nothing short of a full re-cap is necessary.
Good to know. I've got another one on the bench as we speak!
Was looking on entirely something different and accidentally fell over here...lol had mine repaired 1 year ago for pretty much the same reasons + full recap the unit.
Well done :-D, it's alive and kicking ear drums again lol.
Nad was always so expensive, they put the money inside, not outside, The reason they looked boring as hell.
Nads are supposed to be a good quality, but i have had ones for repair and they don't look too special to me.
Ooow that protect pcb was horrible, manufacturers always put capacitors near hot parts, i'm sure they do it on purpose. :-(
If that was my amp, the large resistor would be mounted on the back of the pcb (less direct heating) and the diode leads bent 90 degrees so it sat above the board edge, well away from the crapacitors.
But thats me.
Heat = dead parts :-(
Thanks mate, she's an old donkey now, done well to last this long I guess.
@@JonnyFix You are right, as you often are :-D
This is a silly question but have you noticed the habit of manufacturers putting electrolitics close to heatsinks and other hot areas?
And what fails more often than anything else.... crapacitors hmm lol.
@@zx8401ztv guess so. I don't pay too much attention to layout but it does seem to be an issue. But when is the earliest that something fails with good quality caps? This thing has only just become a problem and it's probably 6-10 yrs in most gear so while electros are an issue it's not like we aren't getting fair use out of this stuff, except for the extreme on 8hrs+ every day situations.
It is a nightmare to fix theese circular solder cracks, NAD usually have a lot of them
Been missing your videos.
Been a while for sure, cheers!
I have a NAD C372 and it recently stopped working so I opened it up and noticed that it needed a new fuse however once I replaced the it just blows them out. Any thoughts?
The mains fuse is 6.3A rated. Looks like it feeds a standby circuit and the main transformer only after turn on. If it blows as soon as plugged in check bridge rectifier B701 for shorts between all pins. If ok check capacitor C709 after IC701 (7805 5V reg) for short across its pins. If it only blows when you switch it on check for shorts across bridges B703, 704 705 and 706 after the larger transformer and so on down the line. Service manual with schematic is free, just google, you will see what I'm referring to. Good luck!
Hi, My NAD C356BEE amplifier makes continues clicking noise and standby light starts blinking on power switch when I try to switch ON'. Also it keeps on standby mode for long time. Before it happens some times but now it comes more often. Some times it gets power ON' and keeps running without no issue till power OFF'. I am looking for a solution to fix this. Please help me to resolve this issue!.
Download schematic, make sure all voltage rails are present that should be while in standby, especially the 5V one. If 5V is bad then troubleshoot power supply that creates this on page 15, maybe caps C545 and C533. If 5V is ok check relay control circuit for relay RL51. High voltage here, use caution.
Hi,how to connect two 8ohm speakers.
Hey there, I have a C370 NAD amp that has just done the same thing - how do I go about getting it to you to fix. I am in Dunedin, NZ
I fixed mine, I live in Tauranga and couldn't find anyone local. The board he fixes failed on mine but I put the diode that gets hot on the opposite side of the board. Next repair was dry joints on the amplifier boards. I need to replace all the capacitors if I can find a kit - like they sell overseas apparently. Much easier to get someone else to fix but not a lot of people around doing this!
Would you service my NAD unit? I live in the United States.
Even if I was taking jobs it wouldn't be worth the freight cost. There must be someone local who can help you. I recommend youtuber norcal715.
You need your NADs servicing eh? 12voltvids perhaps?