2sk135 2sj50 - Page 2

peranders · 10th April 2003, 07:35 AM

I have also a special feeling for these transistors. My first MOSFET amp was built in 1983 and is still working. The original transistors delivered 2 x 285 W at 4 ohm but later I changed them and then got 2 x 500 W!

I you are pleased with the sound, no reason for changing but I have a friend which had difficult speakers and together with a high output impedance amp they sounded peculiar. They sounded allright with a "normal" amp.

wuffwaff · 10th April 2003, 11:55 AM

Hi,

I also build 4 or 5 amps with 2sj50/2sk135. The oldest must be almost 20 years old by now and it´s still working.

I also experimented with bias. Big improvement up to 200mA, after that still getting better but more subtle.

I also used them without source resistors but found it a bit difficult to check the bias per device so now I´m using 5x1watt resistors per fet.

Here´s a picture of my current amp

william

Bernhard · 12th April 2003, 06:44 PM

Are there data sheets also for the 2SJ55 / 2SK175 ?

Where can I find theese or BUZ 900 series at reasonable price ?

I like to built the monolytic supersymmetry amp with them.

Patrick · 13th April 2003, 07:01 AM

Hello.

I need help with an amp that i have received, it was a kitset DT MOS 250.

this included a working PCB, filter caps and center tapp transformer (50V 0V 50V).

the main problem if the wire up of the power transformer.
the design is this:

but i dont know exactly where the output goes.

could someone please help me.
also what does the +ve and -ve on the PCB repersent, is this the speaker output? And where does the power +ve GND and -ve go?

thanks.

Patrick · 13th April 2003, 08:31 AM

s didn't want to load for you, just as they diddn't for me, please go here:

http://www25.brinkster.com/pbridgman/img/pcb.jpg

http://www25.brinkster.com/pbridgman/img/diag.jpg

this will make my previous post more sence.

pinkmouse · 13th April 2003, 08:46 AM

Quote:

Originally posted by Patrick

also what does the +ve and -ve on the PCB repersent, is this the speaker output? And where does the power +ve GND and -ve go?

Hi Patrick

It looks like your website won't allow external linking to images

A long as they are under 100k you can an image to each post by using the button at the bottom of the reply page. If this fails, email them to me and I will post them for you.

I will reserve further comments until the pics are up, cos its easy to make mistakes without all the evidence

Patrick · 13th April 2003, 08:51 AM

Sorry.

if this doesn't work, just copy the link into your browser.

http://www25.brinkster.com/pbridgman/main.htm

(i don't like brinkster that much).

pinkmouse · 13th April 2003, 09:12 AM

Ok

Input looks ok, +&- ve are the power inputs, and the connections at the top are probably earth and speaker output. To pin down the earth a little better could you post a pic of the track side of the PCB?

The return from the speaker will go to a star earth point,( as will the other earth connections), and that is something that will need to be made when the enclosure is built.

Patrick · 13th April 2003, 09:47 AM

I've got more images on the same web site www25.brinkster.com/pbridgman/main.htm

I also have another one of these amps which is half wired up (these were Salvaged and some wires were cut but they do work)
and if you look carefuly at the power wires they do go into the two close unmarked wires (ignore the colour coding i think it is incorrect) and the wire that i have marked as disconnected had come from a power on delay unit. And the two -ve and +ve wires are not connected to any thing.
but i am still confused about which is +ve power, -ve power and GND.

megajocke · 13th April 2003, 12:57 PM

It looks like:

The one marked +ve is positive power, the one marked -ve is negative power.

The wire to the right, above that resistor with a coil on the outside is speaker out, The left one is speaker and power common. (this seems to be right looking at unit number 2)

Input signal is the right one and common the left one. Is the screen on the input cable connected to the left one? (if it isn't that is weird)

What is the resistance between input common and output common? You might need to connect them externally.

Ugh... the wire colors on the second unit are totally messed up

Red for ground??? Never seen that before... Black wire for speaker out? Both positive and negative power red

But are you sure what you are doing? Be careful at least...

10th April 2003, 07:35 AM	#11
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	I have also a special feeling for these transistors. My first MOSFET amp was built in 1983 and is still working. The original transistors delivered 2 x 285 W at 4 ohm but later I changed them and then got 2 x 500 W! I you are pleased with the sound, no reason for changing but I have a friend which had difficult speakers and together with a high output impedance amp they sounded peculiar. They sounded allright with a "normal" amp. __________________ /Per-Anders (my first name) or P-A as my friends call me Tube Buffered Gainclone in work \|Thread

13th April 2003, 09:12 AM	#18
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Ok Input looks ok, +&- ve are the power inputs, and the connections at the top are probably earth and speaker output. To pin down the earth a little better could you post a pic of the track side of the PCB? The return from the speaker will go to a star earth point,( as will the other earth connections), and that is something that will need to be made when the enclosure is built. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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12th April 2003, 06:44 PM	#13
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	Are there data sheets also for the 2SJ55 / 2SK175 ? Where can I find theese or BUZ 900 series at reasonable price ? I like to built the monolytic supersymmetry amp with them.

13th April 2003, 07:01 AM	#14
Patrick diyAudio Member Join Date: Apr 2003 Location: Hamilton	Hello. I need help with an amp that i have received, it was a kitset DT MOS 250. this included a working PCB, filter caps and center tapp transformer (50V 0V 50V). the main problem if the wire up of the power transformer. the design is this: but i dont know exactly where the output goes. could someone please help me. also what does the +ve and -ve on the PCB repersent, is this the speaker output? And where does the power +ve GND and -ve go? thanks.

13th April 2003, 08:31 AM	#15
Patrick diyAudio Member Join Date: Apr 2003 Location: Hamilton	s didn't want to load for you, just as they diddn't for me, please go here: http://www25.brinkster.com/pbridgman/img/pcb.jpg http://www25.brinkster.com/pbridgman/img/diag.jpg this will make my previous post more sence.

13th April 2003, 08:51 AM	#17
Patrick diyAudio Member Join Date: Apr 2003 Location: Hamilton	Sorry. if this doesn't work, just copy the link into your browser. http://www25.brinkster.com/pbridgman/main.htm (i don't like brinkster that much).

13th April 2003, 09:47 AM	#19
Patrick diyAudio Member Join Date: Apr 2003 Location: Hamilton	I've got more images on the same web site www25.brinkster.com/pbridgman/main.htm I also have another one of these amps which is half wired up (these were Salvaged and some wires were cut but they do work) and if you look carefuly at the power wires they do go into the two close unmarked wires (ignore the colour coding i think it is incorrect) and the wire that i have marked as disconnected had come from a power on delay unit. And the two -ve and +ve wires are not connected to any thing. but i am still confused about which is +ve power, -ve power and GND.

13th April 2003, 12:57 PM	#20
megajocke diyAudio Member Join Date: Jan 2003	It looks like: The one marked +ve is positive power, the one marked -ve is negative power. The wire to the right, above that resistor with a coil on the outside is speaker out, The left one is speaker and power common. (this seems to be right looking at unit number 2) Input signal is the right one and common the left one. Is the screen on the input cable connected to the left one? (if it isn't that is weird) What is the resistance between input common and output common? You might need to connect them externally. Ugh... the wire colors on the second unit are totally messed up Red for ground??? Never seen that before... Black wire for speaker out? Both positive and negative power red But are you sure what you are doing? Be careful at least...