hi amp experts,
I have old technics se9060 amp, which needs power transistor replacements.
I got the schematics from ma_coule, thanks Janko.
Original transistors are 2SD675 and 2SB655. I suppose these are obsolete. Can anyone suggest replacements? Even better, can anyone offer two pairs (I would like to replace both channels) replacement transistors for sale? I will gladly pay premium if they are not fake.
thanks,
ed
I have old technics se9060 amp, which needs power transistor replacements.
I got the schematics from ma_coule, thanks Janko.
Original transistors are 2SD675 and 2SB655. I suppose these are obsolete. Can anyone suggest replacements? Even better, can anyone offer two pairs (I would like to replace both channels) replacement transistors for sale? I will gladly pay premium if they are not fake.
thanks,
ed
Hi Steve,
transistors arrived and were easily replaced. No soldering, just two screws, slide new in and that's it. Works great. Thanks Steve for the transistor replacement suggestion. I readjusted DC points as per schematics thanks to Janko Kolar. Thanks Janko.
I like this amplifier. It has decent sound, smooth, sweet and delicate. Massively built, nice overkill power supply, actually two independent ones.
The only think I hate about this amp is its output connectors. I will have to replace them. They only accept bare wire. Weird.
Anyway, its playing now. Sweet, sweet success!
transistors arrived and were easily replaced. No soldering, just two screws, slide new in and that's it. Works great. Thanks Steve for the transistor replacement suggestion. I readjusted DC points as per schematics thanks to Janko Kolar. Thanks Janko.
I like this amplifier. It has decent sound, smooth, sweet and delicate. Massively built, nice overkill power supply, actually two independent ones.
The only think I hate about this amp is its output connectors. I will have to replace them. They only accept bare wire. Weird.
Anyway, its playing now. Sweet, sweet success!
hi bobodioulasso,
yes, I can email you the schematics, I have it, once I get home...
soundwise, yes, it sounds little laid back, relaxed comparing to other amps, I like its sound, its sweet, never too bright
I use it to power the woofers in biamplified system, its great for that
ed
yes, I can email you the schematics, I have it, once I get home...
soundwise, yes, it sounds little laid back, relaxed comparing to other amps, I like its sound, its sweet, never too bright
I use it to power the woofers in biamplified system, its great for that
ed
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That looks to be a Technics custom IC house code number. I doubt you'll find specs on it but you can determine from the voltages present and the very few dual audio JFETS available, what realistic options you have.
I doubt these are original parts, but you could try suppliers like this one if you want (allegedly) the same ones: Encompass Parts: Panasonic SVIUPA63H1 Transistor
I doubt these are original parts, but you could try suppliers like this one if you want (allegedly) the same ones: Encompass Parts: Panasonic SVIUPA63H1 Transistor
Hi guys. Almost a year later but still relevant... 
I also have a Technics SE-9060 power amplifier. My transistors are just fine, however I intend on replacing them as a sort of upgrade and to make sure they do not fail on me.
I have ordered the MJ15024/25 from ebay.
I will let you all know how things turn out, but for now I can let you know about a tweak I have made based on this article:
Adjusting the Bias Of Your Amp [English]
In short, I have adjusted DC offset at the speaker outputs and tuned it to as close to 0V as possible - as the service manual recommends.
But the non-standard tweak (do this at your own risk) I have done is about adjusting the transistor quiescent current. Standard values are 20mV, but I have adjusted them to about 90mV at the moment and the sound has really improved. I have more bass, and in general clarity has improved. However, as expected, both transistors are producing more heat. The right channel seems to be producing more heat than the left. My friend told me that this (uneven heat) is a possible sign of upcoming transistor failure, and pushing voltages and temperatures beyond stock cant be a good thing in that regard - hence another reason why I am going to change the transistors.
With time I intend on fully restoring this amplifier and its accompanying SU-9070 preamplifier to their former glory by changing out all the electrolytic capacitors and maybe a few other things like terminals etc. I will let you guys know how it all turns out. If you have this power amplifier or preamplifier let us know what you have done with them!
I also have a Technics SE-9060 power amplifier. My transistors are just fine, however I intend on replacing them as a sort of upgrade and to make sure they do not fail on me.
I have ordered the MJ15024/25 from ebay.
I will let you all know how things turn out, but for now I can let you know about a tweak I have made based on this article:
Adjusting the Bias Of Your Amp [English]
In short, I have adjusted DC offset at the speaker outputs and tuned it to as close to 0V as possible - as the service manual recommends.
But the non-standard tweak (do this at your own risk) I have done is about adjusting the transistor quiescent current. Standard values are 20mV, but I have adjusted them to about 90mV at the moment and the sound has really improved. I have more bass, and in general clarity has improved. However, as expected, both transistors are producing more heat. The right channel seems to be producing more heat than the left. My friend told me that this (uneven heat) is a possible sign of upcoming transistor failure, and pushing voltages and temperatures beyond stock cant be a good thing in that regard - hence another reason why I am going to change the transistors.
With time I intend on fully restoring this amplifier and its accompanying SU-9070 preamplifier to their former glory by changing out all the electrolytic capacitors and maybe a few other things like terminals etc. I will let you guys know how it all turns out. If you have this power amplifier or preamplifier let us know what you have done with them!
I have returned the transistor quiescent current back to stock values or close to them. I have installed the MJ15024/25 transistors and I can say that I am really happy with the upgrade. The sound is better than the original transistors in all areas (at least the ~37 year old ones in my power amp). Better than both the stock and 'high quiescent current' sound of the previous transistors.
Beware of fake transistors!
It turns out that the transistors I bought were fake (left channel died on me)... it's a good thing that I didn't throw out the old original transistors.
The fakes did sound better, but that doesnt mean anything if they fail on you within a year.
I'm just thankful that they did not damage the rest of the power amplifier.
I have replaced nearly all of the electrolytic capacitors in this power amp, and will change the rest soon.
To be replaced: 8 x 4.7uF 63V (elna silmic II 4.7uF 100V)
3 x 1uF 63V (nichicon FW 1uF 100V)
It turns out that the transistors I bought were fake (left channel died on me)... it's a good thing that I didn't throw out the old original transistors.
The fakes did sound better, but that doesnt mean anything if they fail on you within a year.
I'm just thankful that they did not damage the rest of the power amplifier.
I have replaced nearly all of the electrolytic capacitors in this power amp, and will change the rest soon.
To be replaced: 8 x 4.7uF 63V (elna silmic II 4.7uF 100V)
3 x 1uF 63V (nichicon FW 1uF 100V)
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