| NEC transistor equivalents, for old NAD amp - Click HERE for Original Thread |
| Hamish |
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:bawling:
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 |
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| halojoy |
Guess it is a VERY old NAD. NAD 3020 was one old classic.
But surely transistor replacements are to be find.
Are you going to replace the Electrolytic Capacitors?
It is a good idea on old Amplifiers.
The (volume)-potentiometers and switches can also need a replace. |
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| UrSv |
Is it 3045 and not 304?
/UrSv |
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| 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!:D
Hamish |
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| Vigier |
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 |
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| Hamish |
suffix for the 2sb539 is r53
suffix for the d287b is r79a.
i hope this is right! there is no other lettering on the case (photo looks same except for lower codes):confused: |
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| Vigier |
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 :) |
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| janneman |
| quote: | Originally posted by Vigier
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) |
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| Vigier |
Good idea Jan,
replace the base-resistors of the MJ/2N pair with higher values, and reset the bias-current (try 50mA).
But, if your bias-current is TOO high, probably your heatsink is VERY hot!
Grtz, Joris |
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| halojoy |
I wonder if the low freq, can be due to ALL dried out Big Electrolyts in the power supply.
But could that lead to frying? |
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| jean-paul |
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 ) |
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| Hamish |
if anyone can help, i would chew off my own arm for schematics for this amp:yes: . would it be similar to the 3020? :scratch:
thanks for all your help so far. (i'm on a steep learning curve, so bear with me) |
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| halojoy |
| quote: | Originally posted by Hamish
if anyone can help, i would chew off my own arm for schematics for this amp:yes: . would it be similar to the 3020? :scratch:
thanks for all your help so far. (i'm on a steep learning curve, so bear with me) |
You should contact NAD website.
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. |
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| Andypairo |
If I remember correctly i have 2 pairs of these transistors, removed from a old Denon; I tried them and they do work, If you want I can remove them from the heatsink and send them to you.
Regards
Andypairo
:D |
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| planet10 |
The 3045 is from the generation just before the 3020. We started selling NAD just as these were going end-of-line (late 70s). I will check to see if Steve has the service manual.
dave |
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| Andy_Mac |
Dave, while we are on the topic of NAD, could you ask Steve if he has the service manual for a 3140.
thanks
..Andy |
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| planet10 |
| quote: | Originally posted by Andy_Mac
Dave, while we are on the topic of NAD, could you ask Steve if he has the service manual for a 3140.
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I have the 3045 manual, and i had already borrowed the 2140 manual (power amp only version of 3140 -- got a hum in mine), will that do?
dave |
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| Hamish |
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.
:D :D :D :D :D :D :D :D :D :D :D :D |
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| Hamish |
halojoy,
hjenkins is me! i am trying anything i can. "Audio Asylum" was probably a bit of a mistake. just a bunch of guys moaning about expensive power cords. |
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| Andypairo |
Ok Hamish. Let me know something when you're ready.
Cheers
Andrea |
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| halojoy |
:D Hamish
so you do not have to email that guy
to get into contact with him :D
- makes it a lot easier - |
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| G |
I checked at MCM Electronics for the part numbers you posted and These replacement numbers came up:
2SD555 replaces 2SD287
2SB554 replaces 2SB539
The 2SC2690 is still available.
I hope this helps.
Also check out Brigar Electronics on the web. They have 63V 15000uF "computer grade" caps for 5 buck apiece. They are labeled "McIntosh".
G |
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| Andy_Mac |
| quote: | Originally posted by planet10
I have the 3045 manual, and i had already borrowed the 2140 manual (power amp only version of 3140 -- got a hum in mine), will that do?
dave |
Dave, now for the 64 thousand dollar question, can you send the 2140 manual as a pdf file or is it too big?
...Andy |
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| planet10 |
| quote: | Originally posted by Andy_Mac
Dave, now for the 64 thousand dollar question, can you send the 2140 manual as a pdf file or is it too big?
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1st i have to make the pdf (and scan the rest of the service note), then i'll put it up for temprary download. I have the schematic ready as a gif (<200k) if you'd like to mail me so i can reply with attachment.
dave |
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| Hamish |
Planet10,
can you post the 3045 manual with the 2140?
Thanks,
Hamish
:cloud9: |
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| planet10 |
| quote: | Originally posted by Hamish
can you post the 3045 manual with the 2140?
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Once i get it scanned, yes... been going thru scanners like crazy. Just had a Canon fail after less than 24 hrs :(
dave |
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| Hamish |
Thanks Dave. No hurry.
Hamish:spin: |
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| arkadius69 |
i am the lucky owner of nad 3045.it still works perfectly after all these years.what i am really desperately lookin' for is service manual for this classic amp.
can anyone help me please?:) |
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| serge_ns |
| quote: | Originally posted by planet10
Once i get it scanned, yes... been going thru scanners like crazy. Just had a Canon fail after less than 24 hrs :(
dave |
Could you please send me those manuals if they are still available? Thanks in advance.
Actually I'm looking for NAD3140 manual, but it looks like nobody ever scanned and published it. |
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