Greetings,
As the title says a 110v version of an NAD amp was plugged in 220v mains thereby releasing its "magic" smoke. Certainly the whole power board is fried - maybe the amp boards as well. The question is - is it worth repairing it or will it be more economical to get a new one?
Anyone out there with experience in these types of repairs?
As the title says a 110v version of an NAD amp was plugged in 220v mains thereby releasing its "magic" smoke. Certainly the whole power board is fried - maybe the amp boards as well. The question is - is it worth repairing it or will it be more economical to get a new one?
Anyone out there with experience in these types of repairs?
I've repaired a few amps, mostly through buying of ebay, repairing and selling on. Best step at this point is to open up the unit, take some pictures and post them. Pay special attention to areas that look/smell burnt.
If the board is fried, do you have alternative you power supplies you can use to test the amplifier itself?
If the board is fried, do you have alternative you power supplies you can use to test the amplifier itself?
In my book, "the PCB is the amplifier", meaning :
a) you can buy all other parts over the counter and replace bad ones by same or functionally equivalent.
Furthermore, same basic parts fit thousands of different designs.
b) that PCB is for that amp only, and you can't buy it anywhere.
At most, a few (*very* few) manufacturers offer a new , already built PCB, ready to plug in, at a price lower than the New amp (list price) but often higher than buying a working used one.
So in a nutshell, if you killed the PCB, forget it.
At best, you have a nice chassis, enclosure, transformer and some hardware to build something that fits.
a) you can buy all other parts over the counter and replace bad ones by same or functionally equivalent.
Furthermore, same basic parts fit thousands of different designs.
b) that PCB is for that amp only, and you can't buy it anywhere.
At most, a few (*very* few) manufacturers offer a new , already built PCB, ready to plug in, at a price lower than the New amp (list price) but often higher than buying a working used one.
So in a nutshell, if you killed the PCB, forget it.
At best, you have a nice chassis, enclosure, transformer and some hardware to build something that fits.
A forum member has left a link to his site where there is a good copy of the 216THX schematic: http://dymas.ii.uam.es/~jga/nad216thx/nad-216-sch.jpg
I kinda wish I hadn't looked though, if this has burned badly, there is no way I would have the patience to repair the board and refit that number of parts.
I kinda wish I hadn't looked though, if this has burned badly, there is no way I would have the patience to repair the board and refit that number of parts.
I am surprised the mains fuse did not blow while the saturated transformer tried to charge the smoothing caps up to twice their normal operating voltage.
I wonder what unsuitable size of mains fuse was used for that first power up?
I wonder why you rejected the safer mains bulb tester version of first power up?
I wonder what unsuitable size of mains fuse was used for that first power up?
I wonder why you rejected the safer mains bulb tester version of first power up?
if it was set up for 110V it sure was fused for 110V. so twice the normal main fuse size.
Thanks for all the replies.
Truth be told, It is my dad's amplifier that blew. I will be home in a months time so I will tackle the repair. I have found the schematics for the amp (216 (Non THX version) and it doesn't look too bad - decent modular design. I really hope the damage is limited to the power supply board and not the amp boards. In any case, I will post pictures and report the status of the repair when I tackle it.
Truth be told, It is my dad's amplifier that blew. I will be home in a months time so I will tackle the repair. I have found the schematics for the amp (216 (Non THX version) and it doesn't look too bad - decent modular design. I really hope the damage is limited to the power supply board and not the amp boards. In any case, I will post pictures and report the status of the repair when I tackle it.
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Well, we are assuming a lot of things the OP did not mention at all.
1) did the mains fuse blow?
2) did some other fuse or equivalent blow/open?
Such as a bench power line/wall outlet/extension strip/home fuse or circuit breaker.
3) did he *see* burnt PCBs or he *assumes* some burnt?
4) did the main electrolytics blow/bulge/nothing?
5) do the transformer primary wires show continuity?
6) does the transformer buzz/smoke/bubble/unbearably overheat/blow a 4A fuse connected to the 230V tap? With secondaries disconnected and "floating in the air".
In my experience small transformers die instantly (say 15/30W stuff) because primary wire is so thin that it *instantly* vaporizes, working like a fuse.
While in big amps, the wall outlet can't provide *that* much current, and often even an oversized fuse blows.
In a nutshell: big transformers often survive this.
What dies quickly is power semiconductors (a couple milliseconds) and later big capacitors ... but there's a time constant involved here, lots of mass to heat first (same with transformers) so many survive for long enough (a couple seconds) until the fuse blows or a main breaker trips.
But until further confirmation, we are in the dark.
What I'm surprised is to find so *little* protection.
Only a mains fuse, no inrush limiter, no secondary fuses (which are mandatory for sale in Europe), no separate +/-V rails fuses feeding each power amp.
Strange.
1) did the mains fuse blow?
2) did some other fuse or equivalent blow/open?
Such as a bench power line/wall outlet/extension strip/home fuse or circuit breaker.
3) did he *see* burnt PCBs or he *assumes* some burnt?
4) did the main electrolytics blow/bulge/nothing?
5) do the transformer primary wires show continuity?
6) does the transformer buzz/smoke/bubble/unbearably overheat/blow a 4A fuse connected to the 230V tap? With secondaries disconnected and "floating in the air".
In my experience small transformers die instantly (say 15/30W stuff) because primary wire is so thin that it *instantly* vaporizes, working like a fuse.
While in big amps, the wall outlet can't provide *that* much current, and often even an oversized fuse blows.
In a nutshell: big transformers often survive this.
What dies quickly is power semiconductors (a couple milliseconds) and later big capacitors ... but there's a time constant involved here, lots of mass to heat first (same with transformers) so many survive for long enough (a couple seconds) until the fuse blows or a main breaker trips.
But until further confirmation, we are in the dark.
What I'm surprised is to find so *little* protection.
Only a mains fuse, no inrush limiter, no secondary fuses (which are mandatory for sale in Europe), no separate +/-V rails fuses feeding each power amp.
Strange.
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