Hafler DH-220

[gcohen]

Hello all,

I have an Haflar DH-220 with burnt output mosfets.
Since these are quite expensive I wonder if someone have tried
to put an IRF devices, e.g., IRF240 and IRF9240 instead of the
2SK134/2SJ49 .

Thanks in advance,
Guy

 

[anatech]

Hi Guy,
Won't work. The bias characteristics are different. The IRF devices are completely different beasts.

-Chris

 

[edl]

Hello all,

I have an Haflar DH-220 with burnt output mosfets.
Since these are quite expensive I wonder if someone have tried
to put an IRF devices, e.g., IRF240 and IRF9240 instead of the
2SK134/2SJ49 .

Thanks in advance,
Guy

Hi,

don't even try these IRF devices.
Let's use the 2sk1058/2sj162 pair.

Regards,

 

[Dick West]

gcohen,

Did you test and check your present Lateral Hitachi MOSFETs? How do you know they are burnt? These are very rugged devices. Tell us more.

But, the other posters are correct, you can't use vertical MOSFETs (IRF devices) to replace Lateral MOSFETs (Hitachi).

Profusion (UK) sells replacements for Hitachi devices. Go here:

http://www.profusionplc.com/static/subsites/exicon.htm

But, they must be matched ±10% on Vgs and matched pairs can get expensive.

 

[jackinnj]

Hitachi doesn't make the Lateral MOSFET's anymore -- they're done by Renesas -- http://www.tech-diy.com/LATFET.htm -- shameless plug

 

[gcohen]

DH-220

Hello all,

Thanks for your help. I was affraid that the IRF parts will not
work. There is a guy who says that he did such a modification
in his SCS amp, please see here:

http://aga.rru.com/TechTips/disp.cgi?file=RobertBraught/PowerFETRepl.tt

I know that one of my 2SK134 in my Hafler is burnt since it
is shorted between source and gate.

Surprisingle, I do not find any other shorted component.

Thanks again,
Guy

 

[Roar Malmin]

I have 50 pairs of 2SK175 / 2SJ55 Hitachi MOSFET`S. They are the same, only difference is higher voltage rating and higher current capability. These are new and unused, and they are all from the same batch, so there is no need to match them.
Roar

 

[anatech]

Hello Guy,
I've tried on different amps with varing results. I'll rephrase my earlier statement.

As best, they do not work properly, worst case they will go into thermal runaway and cook themselves to death.

Don't do it. Jackinnj gave you a workable solution.

-Chris

 

[gcohen]

Hello all,

Thanks again for your help.

If I will buy replacements, I will buy a 2SK135/2SJ50 and not
2SK134/2SK49 - This will force me to buy four transistors.
and to accept the differences between the two channels (since
the other channel is original 2SK134/2SK49).

The price of two matched pairs start to be very close to the
price of buying another Hafler DH-220 in ebay!

So, I will see what to do. Thanks anyway.

Guy

 

[edl]

Hi,

You can use the buz900/buz905 or the buz901/buz906 pairs too.

Good luck,

 

[Dick West]

gcohen

I just sent you a PM (email) about two matched sets of MOSFETs.

 

[ERI]

Roar Malmin,
This is a year late, but Google lead me to the post about the possible availability of 2SK134-2SJ49 Hitachi MOSFETs. Are some still available? I am attempting to rebuild an Acoustat TN200 amp. One of the six output devices on one channel became open, and I would rather replace all of the devices than try to find a matching device.

By constant current sourcing the differential input, significantly lowering the output impedance of the low voltage power supply, and shunting the output (power supply) capacitors with fast and linear film capacitors for frequencies above 2kHz, the amp becomes surprisingly transparent and neutral.

I thank you in advance for your assistance.
eri

 

[Roar Malmin]

Hi ERI,

Please contact me via my mail.

Roar

 

[markd514]

Of course the irfs will work! You have to modify the bias and previous stage slightly. I am sure there is an easier way to do it. No, you cant just drop them in. I built a class ab amp with irf verticals and it sounds great.