By finding equivalents yes (I will keep them in my component drawers), not finding them and be constrained to buy who knows where at the prices I've seen on the ebays's link: not (it's not worth for me). I think I will return it to the owner. He should send it to the Tech Support then. I thought to be lucky and to help him quickly but I'm not.
2SK223: not any datasheet found. Any equivalent?
- Thread starter Tormy
- Start date
Help Support GroupDIY Audio Forum:
They’re available in large quantities here but if you have difficulty sourcing then best to hand it over. Plus even if you find the original you may still need to have test gear to match up a pair - this means buying a fair few to get a well marched pair. When matching 1% resistors I usually buy at least 20 to get 2 that are close enough to each other for the circuit requirements - sometimes more if I have no luck but out of 20 I can usually find a pair. Some of the synths I work on have to have close matched resistances in their filter stages. FETs can be a lot harder.
MidnightArrakis
Well-known member
[what is a suitable equivalent for it?] -- See the website URL below:
https://www.datasheets360.com/part/detail/2sk223/-1498423832769112033/
Here is a list of -- 2SK223 Equivalents -- but, they are all discontinued. However, you may be able to still buy some of these from various vendors who specialize in "obsolete" components:
Here is a supplier that has the 2SK223 itself in stock for USD $1.80:
https://www.wagneronline.com.au/2sk/semiconductors/electronic-components/2sk223-22337/959285/pd/
Your forum information doesn't mention what part of planet Earth you are located in, but here is a supplier in the U.S. that is offering the 2SK223 for USD $0.21 (21-cents) each and they have nearly 600-transistors in stock:
You just gotta know how to search and where to look!!!
/
It’s actually AU$1.80 - about US$1.19 - I posted the same link in #14. It’s a local store about 15min from where I live that does online and counter sales like RS or Element 14. I can buy them in about 6 different local electronics stores here - it’s not like they’re hard to get. Don’t see much point in searching for equivalents if you can get the original part.
If you connected gate to source - and then a 9 v battery across source-emitter , the j-fet must have experienced a very strong, and elevating current-burst before entering some semiconductor-nirvana of it's ( hopefully) own liking. If you aim to end up with some functional circuitry, you better check out how to limit your test-currents so you can keep them within the milliamp-range. But please keep in mind that only very rarely will the active components like transistors and j-fets be faulty in small-signal-circuitry. First you should check for corrosion on connectors, dried out/leaking capacitors,( both film and electrolytic ) damaged /overheated resistors, series-regulators- check supply voltages/ and if there's excessive ripple indicating bad electrolytic caps at the bridge rectifiers. Track the signal from you tone-generator, section by section, check for nominal DC voltages in accordance with the schematic. Only rarely will small-signal transistors and j-fets be faulty. Best regards
Well, since this is in a phantom-powered microphone, i think we can rule out burnt resistors, regulators or bridge rectifiers.
Otherwise, all good general troubleshooting advice though.
If it’s old check the XLR pins are not corroded/oxidized/worn. Wire rot is another issue with older gear - the copper breaks away at and just inside the insulation end point. Dirt deposits on high resistance areas, like around the 3GΩ resistors, will cause all sorts of problems - sometimes people spray the switches in these and the overspray film attracts dirt which sticks to it and this then attracts moisture causing noise and unreliable performance especially when cold. I only use fully evaporative cleaner sprays on switches or syringe injected cleaner/lube for switches that are stubborn.
Not necessarily. The requirements for the FET's are different. The bottom one is the V/I converter so it should favout Gm, the upper one delivers the voltage so must be optimized for it.
A good example of this is the MusicMan guitar amps hybrid cascode outputs, where the bottom is a BJT and the top a vacuum tube.
On the schematics T101 is notated as “selected type” (as is T107) and listed as a J305 for the transformerless TL models - no mention in parts lists of 2SK223 either - only shown is the pinout for 2SK223 on bottom of circuit diagram under 2SK30 - I wonder what the selection criteria are for a J305?
I just repeat what are the testing conditions made by the builder and reported into the datasheet. Often they use 10V. 9V battery is enough and not arming.
JFET are no fully conducting and the current is always limited to the Idss so that they will not pass away.
About the mic: one JFET was not working at all. and after have seen I can't replace it with equivalents and/or find a reliable substitute, I preferred to give it back to the owner. He will send it to the assistance. it will take longer and it wil be more costly, but at least I'm not experimenting things on not-my-ownership stuff
I would guess a basic DC operation test (Vgs(off) and Idss) followed by a noise evaluation.
Test conditions described in datasheets are a very simplified version of the actual experiment, in particular any overcurrent protection in the voltage source is omitted.
Anything can happen during an experiment, in particular having the gate floating, even for a short duration, can result in excessive current.
Unless they mean J305 is the “type selected” and that’s the only selection criterion?
Right except when Gate it's welded to the Source and wires to battery are served by a switch. Of course some extracurrent can occur. But I tested many JFETs in this way and never happened to destroy one, applying this way. Of course a more sophisticated device will minimize the probability of incident. But in many years, I never had the need to go beyond this simple way (yet)
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Voyager10
Well-known member
As I've got a C414B-ULS I thought I'd measure some voltages to help guide what DC parameters we'd be aiming for.
Sadly one of the tantalums had failed shorting the power rail to ground, so I had a bit of a diversion over the weekend sorting it out.
Anyway, now fixed! Here you go:
On mine, T101 is a J305 and T102 had its identifier scrubbed off. Grrr.
Anyway, by my calculations the drain current through T101 and T102 is about 0.22mA, and for this current T101 has a Vgs of -2.0V (at Vds=4.4V) and T102 has a Vgs of -4.4V (at Vds=1.9V).
So T101 and T102 definitely not matched, and T102 will have a pretty high Idss by the looks of it.
Sadly one of the tantalums had failed shorting the power rail to ground, so I had a bit of a diversion over the weekend sorting it out.
Anyway, now fixed! Here you go:
On mine, T101 is a J305 and T102 had its identifier scrubbed off. Grrr.
Anyway, by my calculations the drain current through T101 and T102 is about 0.22mA, and for this current T101 has a Vgs of -2.0V (at Vds=4.4V) and T102 has a Vgs of -4.4V (at Vds=1.9V).
So T101 and T102 definitely not matched, and T102 will have a pretty high Idss by the looks of it.
Thank you really so much
T102 2SK772-E
