at the moment i am TRYING to repair an NAD 3045 intergrated. i am trying to find replacement part numbers for the transistors on the heatsink. 2SB539, D287B (both TO-3cases)and a small TO-126 which has the markings P827 90139. These transistors are on the left channel (which is working fine), but replacements on the right channel are MJ2955 and 2N3055. are these correct? the TO-126 on the right case is marked C2690A. is this correct also?
(the original transistors are NEC)
please, please help me!
much thanks if you can,
Hamish
i am new to this forum, but it seems like a much friendlier place than others. (more helpful too, i hope!)
keep up the good work
(the original transistors are NEC)
please, please help me!
much thanks if you can,
Hamish
i am new to this forum, but it seems like a much friendlier place than others. (more helpful too, i hope!)
keep up the good work
answering both at once...
yes, it is a 3045 (old, old, OLD). Electrolytic caps will be replaced soon (i am a student, so good quality 10,000uF caps are wish-list items). All pots and switches will eventually be changed.
if you guys can help, the left channel works fine, but the right channel has a LOUD low frequency noise (even when the volume is right down). it keeps frying resistors in the right channel also. could this be the amp or pre-amp section? i am new to all this, so don't be to technical.
thanks for the replies. it's nice to know that you can get help from around the world!
Hamish
yes, it is a 3045 (old, old, OLD). Electrolytic caps will be replaced soon (i am a student, so good quality 10,000uF caps are wish-list items). All pots and switches will eventually be changed.
if you guys can help, the left channel works fine, but the right channel has a LOUD low frequency noise (even when the volume is right down). it keeps frying resistors in the right channel also. could this be the amp or pre-amp section? i am new to all this, so don't be to technical.
thanks for the replies. it's nice to know that you can get help from around the world!
Hamish
Hi,
2SD287 = Silicium-N-Channel, 200V, 10A, 100W, 8 Mhz
2SB539 = Silicium-P-Channel, 130V, 10A, 100W, 7.5 Mhz
Not REALLY complementary, but OK, let's get the 2955/3055 info:
The MJ2955 and 2N3055 ARE complementary (so don't look at the prefix), and the spec's are: 100V, 15A, 115W, GBW=2,5 Mhz minimum.
If your DC-voltage isn't TOO high (smaller than 50V symmetric), then there will be no problems.
The GBW is not really a problem, since 2,5 is absolutely high enough.
Grtz, Joris
P.S. 1: C2690A = 2SC2690A in case you didn't know
P.S. 2: Do you have a suffix for the 2SB539
2SD287 = Silicium-N-Channel, 200V, 10A, 100W, 8 Mhz
2SB539 = Silicium-P-Channel, 130V, 10A, 100W, 7.5 Mhz
An externally hosted image should be here but it was not working when we last tested it.
Not REALLY complementary, but OK, let's get the 2955/3055 info:
The MJ2955 and 2N3055 ARE complementary (so don't look at the prefix), and the spec's are: 100V, 15A, 115W, GBW=2,5 Mhz minimum.
If your DC-voltage isn't TOO high (smaller than 50V symmetric), then there will be no problems.
The GBW is not really a problem, since 2,5 is absolutely high enough.
Grtz, Joris
P.S. 1: C2690A = 2SC2690A in case you didn't know
P.S. 2: Do you have a suffix for the 2SB539
Heej,
no, that's a date-code, I hoped for a A, B or C suffix, but well, it's not THAT important.
I don't have the schematic of the amplfier, but I can tell you that the 2SB/2SD transistors are MUCH better than the MJ/2N set. (2SB and 2SD were specially made for audio, while ev'rybody thinks the 2SA/2SC were... MJ and 2N are definitely NOT).
What you could do is replace the Base-resistor with another one with a higher value (what resistor "lighten's up"???)..
That should help a lot. Another possibility: If the amp has emitter-resistors, you can replace them with a higher value (for example from 0.10 Ohm to 0.15 Ohm (MARK THE DISSIPATION!)
The last idea I have is the bias-current setting. Maybe the current is too low for these transistors. If you can measure it, it's an idea to set it at at least 50mA (if it's lower at this moment). If you replace the transistors, you always have to re-measure the bias-current and reset it.
Those were the first things that fell into my mind...
Grtz, Joris
P.S. Please don't comment my english... I'm a Dutch Kaaskop
no, that's a date-code, I hoped for a A, B or C suffix, but well, it's not THAT important.
I don't have the schematic of the amplfier, but I can tell you that the 2SB/2SD transistors are MUCH better than the MJ/2N set. (2SB and 2SD were specially made for audio, while ev'rybody thinks the 2SA/2SC were... MJ and 2N are definitely NOT).
What you could do is replace the Base-resistor with another one with a higher value (what resistor "lighten's up"???)..
That should help a lot. Another possibility: If the amp has emitter-resistors, you can replace them with a higher value (for example from 0.10 Ohm to 0.15 Ohm (MARK THE DISSIPATION!)
The last idea I have is the bias-current setting. Maybe the current is too low for these transistors. If you can measure it, it's an idea to set it at at least 50mA (if it's lower at this moment). If you replace the transistors, you always have to re-measure the bias-current and reset it.
Those were the first things that fell into my mind...
Grtz, Joris
P.S. Please don't comment my english... I'm a Dutch Kaaskop
Vigier said:Heej,
[snip]
The last idea I have is the bias-current setting. Maybe the current is too low for these transistors. If you can measure it, it's an idea to set it at at least 50mA (if it's lower at this moment). If you replace the transistors, you always have to re-measure the bias-current and reset it.
Those were the first things that fell into my mind...
Grtz, Joris
P.S. Please don't comment my english... I'm a Dutch Kaaskop
Since he reported frying the resistors and a loud low freq noise, it may be that the bias is too high (noise could be the transformer straining to keep up the good work. do these things have separate xformers?).
Jan Didden (another Kaaskop)
Did you measure any DC on the output of the right channel ?
If so, probably one of the replacement transistors is defect.Another way for discovering this is measuring the voltage over the emitter resistors ( 0,15 , 0,22 Ohm or something like that ).
I ( current ) = U ( voltage ) / R ( resistance ). Values of currents higher than 0.1 Ampere indicate too high bias or in the case of extreme values broken power transistors.
And please measure the voltages on the driver transistors of the right channel and compare them to the values of the left channel.
Regards,
Jean-Paul ( third Kaaskop in a row )
If so, probably one of the replacement transistors is defect.Another way for discovering this is measuring the voltage over the emitter resistors ( 0,15 , 0,22 Ohm or something like that ).
I ( current ) = U ( voltage ) / R ( resistance ). Values of currents higher than 0.1 Ampere indicate too high bias or in the case of extreme values broken power transistors.
And please measure the voltages on the driver transistors of the right channel and compare them to the values of the left channel.
Regards,
Jean-Paul ( third Kaaskop in a row )
Re: schematics for 3045
That amplifier is old and there is no commercial need to keep the schematic secret.
I am sure they would provide you with a schematic,
if you get help from the right person there.
So use email.
http://www.nadelectronics.com/
I only found one italian guy mentioning NAD 3045 on the net.
and this thread in AudioAsylum.com
NAD 3045 information sought
You can email "hjenkins"
by clicking his name. He is from Australia.
You should contact NAD website.Hamish said:if anyone can help, i would chew off my own arm for schematics for this amp. would it be similar to the 3020?
thanks for all your help so far. (i'm on a steep learning curve, so bear with me)
That amplifier is old and there is no commercial need to keep the schematic secret.
I am sure they would provide you with a schematic,
if you get help from the right person there.
So use email.
http://www.nadelectronics.com/
I only found one italian guy mentioning NAD 3045 on the net.
and this thread in AudioAsylum.com
NAD 3045 information sought
You can email "hjenkins"
by clicking his name. He is from Australia.
fantastic!
that is great news. i don't know how to thank you. thanks for that. i also have a bit of a hum in mine too. i am a bit of a novice with these things, so if you could offer any pointers once i get in to the guts of the thing, that would be even better.
this is just a bit of a warm up really. i have been thinking about building an amp for a while, and due to the recommendations and helpfulness of you guys, i think i will build an Aleph 5. (shouldn't be too hard, but we'll see!)
thanks for all your help, everyone. i think i am becoming a bit addicted to this forum.
Andrea,
i have a sister in the U.K. i will get her address and send some money for postage. it should be easier than mailing the transistors to Australia.
that is great news. i don't know how to thank you. thanks for that. i also have a bit of a hum in mine too. i am a bit of a novice with these things, so if you could offer any pointers once i get in to the guts of the thing, that would be even better.
this is just a bit of a warm up really. i have been thinking about building an amp for a while, and due to the recommendations and helpfulness of you guys, i think i will build an Aleph 5. (shouldn't be too hard, but we'll see!)
thanks for all your help, everyone. i think i am becoming a bit addicted to this forum.
Andrea,
i have a sister in the U.K. i will get her address and send some money for postage. it should be easier than mailing the transistors to Australia.
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