Nad 214

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normally in a NAD 214 you expect to find :

---In the main power supply capacitance is lower than was supposed to be ( there is mounting area on the pcb for more ) and it could be nice to add ...


---Also adding bypass capacitors down under the electrolytic you replace especially in the front end power supply will be nice to do

--- Use of low quality capacitors in the stabilized front end power supply, that also run kinda edgy combined with some temperature might result to plenty of leaks while in other similar amps they actually run much longer there .....better quality ,105 dg ,and maybe higher voltage might be joy ...still size and make can be tricky

---choice of input capacitor is poor and many changed one using better quality than a simple mkt 1mfd

---The protection circuit regarding temperature is made with muting transistors in the input ....IE If amplifier gets warmer than supposed to input is muted Point is that many think that removing transistors form the input makes the amp more clean ( as less in the signal path is possible ) a nice option will be to replace the transistors with audio grade relay

---depending on the serial number you might find that idle is 50% less than specified on service manual ...to my understanding you could follow the service manual instructions or even go up to 30% more than that with any problems

---Finally you need to inspect both main boards for soldering issues ....

here is some pictures and if you need a schematic you can always email me

100_2033.jpg


100_2034.jpg


100_2035.jpg
 
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Did they REALLY mount the transformer with a steel shunt like that?

Modern electrolytic are physically smaller so some gains may be possible. Check the catalogs. As it has 4 caps, are they sperated by a really small resistor to make a pi filter? Or are the caps for each side?

I see it has space for twice as many outputs. From my reading, that has a big advantage providing you have enough drive.
 
Did they REALLY mount the transformer with a steel shunt like that?

Modern electrolytic are physically smaller so some gains may be possible. Check the catalogs. As it has 4 caps, are they sperated by a really small resistor to make a pi filter? Or are the caps for each side?

I see it has space for twice as many outputs. From my reading, that has a big advantage providing you have enough drive.


mounting is kinda weird but still proper isolation and no "winding" over the trafo

as about the size of caps things are not exactly as you describe them cause NAD 214 is not vintage equipment old may but not vintage problems in capacitors are related not especially to age but mostly in quality and range ...so picking up caps might be tricky size wise ...

main filter capacitors are tall and thin .... so that is the number one problem as seen from the photos i had to mod the amplifier to fit nippon caps
 
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Hallo Sakis, From what I have read on the internet it is not good to mount a toroidal like this. The mounting seems to cause a shunt over the transformer. Low volts but high current. The transformer should only be mounted from one side. Does this not waste a lot of the transformers power that can actually influence the working of the amp ?

Regards
Jan
 
Hi everyone, I'm reviving this thread because I just bought a NAD 214 amp and I have a few questions about what was discussed. Please bear with me as I am a bit of an amp N00b.

I searched for replacement power supply caps and found these:

UVY1J472MRD Nichicon | Mouser

63V, 105°C, 4700uF, and I confirmed that the size is ideal. Is there anything I've overlooked about these capacitors? Are they too cheap to be worth installing?

Second, with regard to the input capacitors, is the problem merely the quality of the stock capacitor? Should I replace it with a higher quality 1mfd cap or should I change it to a capacitor of greater value than 1mfd?

Third, looking over the schematic I am unable to identify the muting transistors. Are they TH101/102 "thermal breakers?"

Lastly, I'm also curious about the controversial shunt over the transformer. Does anyone have any insight to the benefits or drawbacks to this shunt?
 
no one replied? what were the results/answers/findings

Hi everyone, I'm reviving this thread because I just bought a NAD 214 amp and I have a few questions about what was discussed. Please bear with me as I am a bit of an amp N00b.

I searched for replacement power supply caps and found these:

UVY1J472MRD Nichicon | Mouser

63V, 105°C, 4700uF, and I confirmed that the size is ideal. Is there anything I've overlooked about these capacitors? Are they too cheap to be worth installing?

Second, with regard to the input capacitors, is the problem merely the quality of the stock capacitor? Should I replace it with a higher quality 1mfd cap or should I change it to a capacitor of greater value than 1mfd?

Third, looking over the schematic I am unable to identify the muting transistors. Are they TH101/102 "thermal breakers?"

Lastly, I'm also curious about the controversial shunt over the transformer. Does anyone have any insight to the benefits or drawbacks to this shunt?

Bump of an old thread but wow it was just getting interesting when it fell off the cliff

no one replied? what were the results/answers/findings
 
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Sakis answered the shunted turn problem in post 7. If such a "shorted half-turn" existed, you would soon know it by a very hot transformer and burnt fuses. To avoid the problem, the metal strut which could form a half-turn on the toroid, will have its ends insulated from each other.

The problem has been well understood in professional design circles for at least 40 years to my knowledge and I came across it in a local electronics magazine back when toroidal transformers became popular in the late 1970s. As DIYs though, we either have to learn the mounting problems the hard way, stumble over them on forums as here or best of all, do some proper study of the topic by a search of papers and magazine archives on the net.
 
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