What's up, everybody.
I have a Sony TA-4650 V-FET amp that caused the previous owner some real problems. The amp does have the original 2SJ18's, but the 2SK60's have been replaced with NTE2392's (N-Channel Mosfet).
I'm sure this combination cannot work. Right?
First, if anyone has a good pair of 2SK60, please let me know how much you would ask me to pay. Second, if anyone needs a good pair of 2SJ18, I may end up parting this unit out - I want to finish the amp, but if I cannot...
ON EBAY,
1PCS 2SK60 Encapsulation:TO-3 | eBay
Is this a REAL replacement part? If it is a copy, can I get away with using it in this amp? I see that other buyers have purchased this product (as seen the sold listings), but there have been no reviews or feedback exclusive to this part. Thanks,
I have a Sony TA-4650 V-FET amp that caused the previous owner some real problems. The amp does have the original 2SJ18's, but the 2SK60's have been replaced with NTE2392's (N-Channel Mosfet).
I'm sure this combination cannot work. Right?
First, if anyone has a good pair of 2SK60, please let me know how much you would ask me to pay. Second, if anyone needs a good pair of 2SJ18, I may end up parting this unit out - I want to finish the amp, but if I cannot...
ON EBAY,
1PCS 2SK60 Encapsulation:TO-3 | eBay
Is this a REAL replacement part? If it is a copy, can I get away with using it in this amp? I see that other buyers have purchased this product (as seen the sold listings), but there have been no reviews or feedback exclusive to this part. Thanks,
If the vertical mosfet is sounding ok then I would leave it rather than start hacking at the pcb to replace it.
Laterals (if you can find them) are expensive.
A few years ago I designed and built a lateral amp and couldn't tell the difference between that and a vertical mosfet amp.
I wouldn't be buying anything SS off ebay. I got stung with some mosfets that blew up when I unplugged my soldering iron ! When I did buy parts from a reputable dealer I couldn't blow them up despite trying very hard. I can only guess the lower breakdown voltage of the fakes was why they died so quickly.
Laterals (if you can find them) are expensive.
A few years ago I designed and built a lateral amp and couldn't tell the difference between that and a vertical mosfet amp.
I wouldn't be buying anything SS off ebay. I got stung with some mosfets that blew up when I unplugged my soldering iron ! When I did buy parts from a reputable dealer I couldn't blow them up despite trying very hard. I can only guess the lower breakdown voltage of the fakes was why they died so quickly.
Vertical mosfet and vfets are different. Vfet is much costlier and difficult to get than lateral fet. vfet output character is similar to triode and normaly on-depletion mode- device,but lateral fet have pentode like curves ,normaly off device-enhancement mode.
please check the rank of the working 2sj18 before buying the 2sk60 fom ebay seller
2sk60-rank53.
please check the rank of the working 2sj18 before buying the 2sk60 fom ebay seller
2sk60-rank53.
Little Diode have the 2SK60 listed but at enormous price.
LittleDiode – Electronic Components for All
LittleDiode – Electronic Components for All
Who cares? Those VFETS aren't any kind of MOSFETS. You're talking about a totally different thing.
Vertical Mosfets are mosfets, but Vfets are not mosfet. Vfet is depletion mode power jfets with triode like characters.Most of them made by Japanese and very few by Russia.
Excuse me but you often chime in before even checking out what device people are referencing. How about simply googling 2SK60, and it would pop out that this is a vertical FET as in JFET, i.e. a depletion device with a negative bias. So now we have 2 pages of replies which actually make no sense regarding the original poster's question.
No standard MOSFET of any kind including lateral will work here.
Obviously a MOSFET will not work here, but it might have caused further damage including to itself. This is because the circuits in the amplifier are capable od supplying a bias voltage that appears between the G and S terminals of the device, that are higher than the G-S breakdown voltage of most MOSFETs.
The TA4650 service manual is available for free on the web. There are numerous posts by many members on this topic, in one of them you will find Sony after-market mods to the output overcurrent protection circuit which you would be prudent to apply when fixing/re-building this amp. At least a partial re-build is highly recommended if a VFET was blown and the amp has never been re-built - it is CRUCIAL that the bias power supplies operate correctly (+-82V) or you run a serious risk of frying a VFET again.
The available posts and manual should be a good guide to properly fixing the amp. In particular, pay attention to matching the VFET 'rank' which is encoded in the last digit of the 4 character string under the type, usually a sequence of two letters and two numbers. ONLY the last digit is relevant and should ideally match between the J and K part. If there is no other way, a mismatch of +-1 is tolerated but there is a caveat, the unit is designed for ranks between 3 and 7 however you should better aim at 4, 5 or 6. Unlike regular semiconductors, the G-S voltages for VFETs are huge - typical idle bias is about 16V (but can vary +-20% with only a 1 difference in the last digit), and the bias circuit has a range of voltages it can produce so it might not be able to accommodate rank 3 or 7 which are at the very lowest and highest settings, depending on component tolerances. I would also not recommend rank 3 because the amp barely satisfies it's published spec when it is used.
As for eBay 2SK60 - and for that matter, other VFETs.
There are attempts to make fakes of these devices and they are truly insidious - a properly functioning VFET, when measured using a diode tester of ohm-meter, reads very closely to a dead bipolar transistor with a C-E short. However, the original Sony TO-3 case has a specific shape, the cap is bulged out and on the bottom it has two indented rings slightly smaller in diameter than the cap, since it is made out of a steel shell and a nickel-ed copper stud that carries the actual silicon, for better heat transfer.
HOWEVER, and this is important, and - unfortunate. As far as I can tell (and not going into details here), most if not all of these come from the same place, and originally, due to handling and storage over the years, in most cases the original markings were partially or completely rubbed off. The result is that very often the markings which they have printed onto the device after cleaning and re-finishing (to make them look new), don't reflect what it actually is. As a result, when you buy a 2SK60 from china, you can get a 2SK60 of any rank, as well as a 2SK82 of any rank, regardless what it says on the case. Obviously this is not good.
I should note that it is possible to approximately know if the rank is right given an original Sony part to compare with, once it is installed in the amplifier (by measuring the G-S voltage once the given idle current has been adjusted for), by that time it's obviously too late if it's not the proper voltage. What is worse, it is not possible to identify a 2SK82 installed instead of 2SK60 using this method.
Unfortunately it is not possible to know for sure without a curve tracer (and not just any one and in any case they are rare and very expensive) or building a test rig which is not at all simple (requires two variable voltage sources one of which is current limited, two volt meters and one ampere meter).
Just recently there was a seller selling 'Vgs tested' Sony VFETs which had wildly varying Vgs, despite the same rank number stamped on them - since Vgs is directly dependent on rank, obviously fake markings, so you have no idea what you actually get.
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Excuse me but I have 40 years experience in electronics and software !
Many many people on here have thanked me for good advice.
So I hadn't come across a rare type of transistor before ?
Get over it, no one knows it all, and you certainly don't !
As for wasted space, your attitude in some of the posts is disgraceful.
Your attitude can put people off replying just in case they might get it wrong.
Now I look back I see I did actually know of that type of transistor.
Its just they arent used as often as enhancement type mosfets so that's why I didn't think it was one of those.
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Misleading and confusing nomenclature...
MOS = Metal Oxide Semiconductor -- Currently, the (terrible) combination of metal gate Schottky barrier-polycrystalline silicon-Hafnium oxide is favoured.
FET = Field Effect Transistor -- According to the institutional scientific opinion, Field Effect Transistors exhibit a force field while the bipolar P-N junction does not.
JFET = Junction Field Effect Transistor -- See below
V-FET = (the “V” being an acronym for “Vertical”) designates Sony`s remarkable technical realization of an equally remarkable working principle. The technologically demanding mass production of V-FET was a remarkable achievement as well.
Being a depletion-mode device, the V-FET shares some of the JFET’s operating characteristics, but the VFET is not a JFET. The JFET has a diffused gate-channel diode and very high input impedance. Here, the junction capacitance arises in the doped P-N junction diode under reverse bias forming the depletion region.
Standard enhancement and depletion-mode MOSFETs have an insulated capacitive gate, wide chip surface area, large interelectrode capacitances and very high input impedance. These utilize strong ion implantation to produce the inversion channel and the depletion layer at the desired low level excitation, which renders the gate electrode into a bulky ionic capacitor.
The V-FET`s gate is rather a resistive component with low input impedance and small input capacitance due to the thick layer of evenly grainy silicon dioxide between gate and source, instead of the dispersive amorphous polysilicon commonly used as a dielectric spacer. The V-FET does not have a P-N junction, but a uniform, low pressure channel current density. A JFET of similar power handling capability would have blatantly disadvantageous properties.
Lacking detrimental epitaxial doping in conjunction with low doping concentration in the inversion channel, the threshold voltage fluctuations are unsuppressed and a five-grade ranking was introduced.
Depletion-mode devices are generally more difficult to manufacture. A counterfeit manufacturer chooses structures that are easy to control by simple technique and cheap tools. It is silly to complicate things unnecessarily.
MOS = Metal Oxide Semiconductor -- Currently, the (terrible) combination of metal gate Schottky barrier-polycrystalline silicon-Hafnium oxide is favoured.
FET = Field Effect Transistor -- According to the institutional scientific opinion, Field Effect Transistors exhibit a force field while the bipolar P-N junction does not.
JFET = Junction Field Effect Transistor -- See below
V-FET = (the “V” being an acronym for “Vertical”) designates Sony`s remarkable technical realization of an equally remarkable working principle. The technologically demanding mass production of V-FET was a remarkable achievement as well.
Being a depletion-mode device, the V-FET shares some of the JFET’s operating characteristics, but the VFET is not a JFET. The JFET has a diffused gate-channel diode and very high input impedance. Here, the junction capacitance arises in the doped P-N junction diode under reverse bias forming the depletion region.
Standard enhancement and depletion-mode MOSFETs have an insulated capacitive gate, wide chip surface area, large interelectrode capacitances and very high input impedance. These utilize strong ion implantation to produce the inversion channel and the depletion layer at the desired low level excitation, which renders the gate electrode into a bulky ionic capacitor.
The V-FET`s gate is rather a resistive component with low input impedance and small input capacitance due to the thick layer of evenly grainy silicon dioxide between gate and source, instead of the dispersive amorphous polysilicon commonly used as a dielectric spacer. The V-FET does not have a P-N junction, but a uniform, low pressure channel current density. A JFET of similar power handling capability would have blatantly disadvantageous properties.
Lacking detrimental epitaxial doping in conjunction with low doping concentration in the inversion channel, the threshold voltage fluctuations are unsuppressed and a five-grade ranking was introduced.
Depletion-mode devices are generally more difficult to manufacture. A counterfeit manufacturer chooses structures that are easy to control by simple technique and cheap tools. It is silly to complicate things unnecessarily.
ilimzn - As always you continue to to be a wealth of V-FET information here on DIY and elsewhere. Thanks you for your comments to date and hoping you'll continue!
Indeed............. only one other person I've run across (member Echowars, who seems to have disappeared - hope he is OK) in my years of owning almost all the Sony VFET amps & integrated amps as well as Yamaha VFET amps is as knowledgeable concerning VFET devices & design as is member ilimzn (hello ilimzn - its been many years - hope all is well).ilimzn - As always you continue to to be a wealth of V-FET information here on DIY and elsewhere. Thanks you for your comments to date and hoping you'll continue!
Too bad the small fab in AZ that made that run of VFETs for Nelson Pass a couple of years ago is no longer available. Would have been nice to have a run of VFETs made to support the Sony & Yamaha units.
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