Where to buy MOSFETs?

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StuartH

Member
Joined 2003
Hi

I am looking for the same components for an old Cloud CV 250 amplifier. I did a search on http://www.usbid.com, and it seems that there are a few devices still avaliable for purchase, although to my mind the price is a little high especially if one were to include shipping to South Africa.

At this stage I am looking around for alternatives. Unfortunately, the datasheets for the 2SK414 and 2SJ119 seem to be even more scarce than the devices themselves. So far I have managed to ascertain the following specs.

Vds = 160V
Id = 8A
Pd = 100W
RdsON = 0.5ohm

If I find a suitable replacement Ill post it here.

cheers/
Stuart
 
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pbrett

Member
Joined 2005
StuartH said:
Just got mail back from Cloud.

They suggested trying the IRFP240/IRFP9240 as alternative's to the 2SK414/2SJ119.
Click to expand...

Having replaced my mosfets with the above alternatives (I shorted an output a while ago and the mosfets blew instead of the fuse), I'm now getting quite a lot of distortion. There are a few preset pots on the board. Do I need to make adjustments? If so what do they adjust? Do these pots allow adjustment to the bias of the mosfets?

Any help here would be gratefully appreciated. While the Inca Tech is now my second amp, it would be nice to get it working again. I'm guessing that tweeking pots and relying on my ears alone to tell me when things are right is not the best way forward from here.
 
Mooly

Mooly

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Joined 2007
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Hi, The 2SJ/2SK sound like lateral MOSFET's . The IRFP240 type are HEXFETS, the characteristics are totally different. Even more important the HEXFET,s have a positive temperature coefficient which means thermal runaway is likely. I am not suprised they sound distorted. If they are laterals the 2SJ162 and 2SK1058 should be suitable replacements.
Regards Karl
 
Mooly

Mooly

Administrator
Joined 2007
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You asked where to get them, problem, non of the suppliers I use list both however check out Exicon you want their ECX10N20 and ECX10P20. These are a T0247 package. The 2SK is an N channel polarity device, the 2SJ is P channel. The quiescent current should be set to around 100ma, and use a 40 or 60 watt filament bulb in series with the mains when initially testing as this will provide good protection if anything is wrong. Good luck with any repair.
Edit, can't get the link to work. It's www.profusionplc.com Navigate to Products/Transistors/Lateral Mosfets
Regards Karl
 
Mooly

Mooly

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Joined 2007
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Hi, Found a datasheet on 2SJ 118/119 your right about the pinout, drain and source reversed compared to 2SJ162.
Are these a HEXFET then as we know them today ? Reading from the datasheet some of the characteristics more like HEXFET and some more like lateral. Cricklewood electronics list the originals at 16GBP each.
Edit, After looking at the datasheet I think these are a bit of a one off, they are not like a modern HEXFET and neither are they like totally like a Lateral. Might be best to source the originals if poss.
Regards Karl
 
P

pbrett

Member
Joined 2005
richie00boy:

Sorry for the confusion, its the Inca Tech.

Mooly:

Are you sure about the IRFP240s being HexFETs? A search on Farnell seems to me to be identifying them as MOSFETs link .
I would have thought that if they were a slot in replacement for the Cloud that they should probably work in the Inca Tech too, but since I couldn't even find data sheets on the original devices, I was kind of flying blind.

Thanks anyway, I might try the Exicon devices anyway, although as has been mentioned on other threads, the quality of the PCBs in these amps is not great. Whether it will stand up to more of my brutal attempts to de-solder and re-solder components is debatable.

Pete
 
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pbrett

Member
Joined 2005
richie00boy said:
No those Hitachi parts are switching vertical devices. If you use laterals such as the Exicon they will perform wrong and they have the wrong pinout.
Click to expand...

Doh! Does anyone have a copy of the data sheets for the Hitachi parts which they could email to me? Alternatively has any one succesfully substituted a different part in an Inca Tech Claymore?

Thanks,
Pete
 
syn08

syn08

Banned
Joined 2005
synaesthesia.ca
2SK414/2SJ119 are vertical MOSFETs (not laterals!) having about 2S transconductance. They are matched for transconductance, while the IRF240/9240 pair is matched for charges (optimized for switching applications)!

The closest replacement today is 2SK1530/2SJ201 from Toshiba. They have 5S tranconductance (I don't think it will harm) and about the same (or close) Ciss. You can get this pair from DigiKey.

Give them a shot, most likely they will work just fine.

Datasheets:

http://pdf1.alldatasheet.com/datasheet-pdf/view/145810/ETC/2SK414.html

http://pdf1.alldatasheet.com/datasheet-pdf/view/108045/ETC/2SJ119.html
 
I

ilimzn

Member
Joined 2005
pbrett said:
Thanks for all your help.

I'm going to try the 2SK1530/2SJ201 from DigiKey at a total cost of around £16 rather than going for the originals for £64. I'll post again when I get this done (hopefully with good news).

Pete
Click to expand...

Actually, 2SK1529/2SJ200 would be a closer substitute, just keep in mind that they have a slightly lower treshold voltage, so before firing up the amop be sure to adjust the bias all the way down, and then after power up (and checking that all is well) adjust it to it's proper value. The reason why you may be getting high distortion with IRFP devices is that their treshold voltages are substantially higher than those of the originals, so they are under-biassed. It may even be possible that the range of bias adjustment will not alow you to bias them properly, without modification to the bias circuit.
 
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