Myst TMA3 transistors Hitachi 2SK226 2SJ82

[hifienthusiast]

I am looking into repairing a Myst TMA3 integrated amp. One channel is not working. Searching the internet, I found the following review which mentions the amp uses Hitachi mosfets for the output stage.

http://www.paulburt.co.uk/pdf/tma3_review.pdf

I would like to find out if these transistors: Hitachi 2SK226 2SJ82 mosfets are available. If not, what are the equivalent part number nowadays in UK.

Many thanks.

Regards
Hon

[AndrewT]

Hi Hon
I posted a similar question recently.
My Sugden used 2sj81 & 2sk225 (120v Vds)
yours are the 140Volt version.
the modern equivalent is 2sj161 & 2sk1057 (140v) or 2sj162 2sk 1058 (160v). Being lateral fets they have negative temp coef and do not need thermal compensation to control Iq. Do not use vertical fets, they have positive coef upto about 6 or so amps and start to run away as they heat up. Why would you want to use verticals 1. they are much cheaper, 2. they are much more robust ( slightly higher power and much higher current capacity).
regards Andrew T.

[hifienthusiast]

Hi Andrew

Thanks for your tips. I looked at your original post about your Sugden P128 which uses the 2sj81 and 2sk255. I also have a Sugden amp, the A21a integrated. It sounds very nice. I haven't looked at the output transistors yet, I only got it 2 weeks ago.

I am hoping that I will get a free Myst integrated amp which has one blown channel, but I haven't heard from the person who is giving it away. Will update the progress if I receive the generous offer from the owner.

Regards
Hon

[hifienthusiast]

I am going to repair a dead channel of a Myst TMA3 . Can someone tell me where I can buy 2sj161 & 2sk1057 or 2sj162 2sk 1058? Thanks.

Hon

[AndrewT]

Hi,
Rapid sell a pair for £7.90 + postage for orders under £25 +VAT.
www.rapidelectronics.co.uk

[hifienthusiast]

Andrew

Many thanks for your help.

Hon

[AndrewT]

Hi,
Rapid just Emailed to say they are offering free post this holiday weekend.

[feynman1977]

Originally posted by AndrewT
Hi Hon
I posted a similar question recently.
My Sugden used 2sj81 & 2sk225 (120v Vds)
yours are the 140Volt version.
the modern equivalent is 2sj161 & 2sk1057 (140v) or 2sj162 2sk 1058 (160v). Being lateral fets they have negative temp coef and do not need thermal compensation to control Iq. Do not use vertical fets, they have positive coef upto about 6 or so amps and start to run away as they heat up. Why would you want to use verticals 1. they are much cheaper, 2. they are much more robust ( slightly higher power and much higher current capacity).
regards Andrew T.

Hello to all, i'm very glad to follow this forum, and this is the first time that I'm trying to write to you (please forgive me for my bad english).

I wish to ask you a question about the vertical and the lateral FET: what do you mean with this classification ? Vertical or Lateral ?

Another question: I don't understand what do you mean about the negative temp coeff (I think that you are talking about the general caracterics of MOSFET, transcond vs. temp or many other ?)

Please forgive me for my questions, also I have this problems, to change the 2SK226 and the 2SJ82 MOSFET's with a new ones, but I don't know if the 2SK 1058 and the 2SJ 162 are the good choice for do this.

By for now,
Ivan

[AndrewT]

Hi,
the 82/226 are the 140v lateral FETs.
You could use either 161/1057 (140v) or 162/1058 (160v) as the modern lateral equivalent.
Vertical FETs are mostly used as high speed, high power switches but some designers have used them to produce good audio amplifiers. Indeed some have developed amps specifically to suit Nchannel vertical FETs because they are so cheap and robust.
Look at the drain current(Id) vs gate to source voltage(Vgs) for various temperatures to see the difference between lateral and vertical FETs. The high vs low voltages and the change with temperature seem to go part of the way to define the practical difference between the two types.

[feynman1977]

Hi Andrew,

your post is clear and I have understand what you mean, thanks for your answer.

I want to ask gently an information: do you have (you or somebody who read this post) the old datasheets for the mosfet 2SK226 and the 2SJ82 ?

If you don't have this one, do you know where I can find the datasheet ? Web site or something else ? I have looked at Hitachi web site, but this datasheets are not avalaible, and I need it for my amplifier.

by for now
Ivan D.C.