Ahhhh ok, question, why are there two of them? There is one on the pcb near the capsule, and another on the pcb opposite of the transformer pcb.
AKG Perception 420 Mod
- Thread starter Gbout2
- Start date
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AUDIO FREQ !
If you don't have a 2sk30a for the faulty microphone input circuit,
Very carefully, without overheating, unsolder the second one from the oscillator, measure its Idss(small) and use it at the input, (there is an adapter of impedance/(preamplifier)).
In dc/dc converter use 2sk105,bf245,bf256,bc264,
2n3819,etc etc, pretty much anything works that isn't fussy.
If you don't have a 2sk30a for the faulty microphone input circuit,
Very carefully, without overheating, unsolder the second one from the oscillator, measure its Idss(small) and use it at the input, (there is an adapter of impedance/(preamplifier)).
In dc/dc converter use 2sk105,bf245,bf256,bc264,
2n3819,etc etc, pretty much anything works that isn't fussy.
So unsolder the K30A from the big pcb, and put it on the top pcb near the capsule. And use one of my 2n3819, and put it in place on the big pcb.AUDIO FREQ !
If you don't have a 2sk30a for the faulty microphone input circuit,
Very carefully, without overheating, unsolder the second one from the oscillator, measure its Idss(small) and use it at the input, (there is an adapter of impedance/(preamplifier)).
In dc/dc converter use 2sk105,bf245,bf256,bc264,
2n3819,etc etc, pretty much anything works that isn't fussy.
Just double-check the datasheets for both, just to make sure you solder the correct pins in the correct places (no idea if the 2N3819 has the same pinout as the 2SK30A).
Attachments
I think they are the same, but backwards from each other. So i will just have to install facing the opposite direction?
What if I try to shave off some of the plastic on the K30A, and solder new legs to the stubs?
Not worth the effort and/or risk.
I did this many times, 50 years ago, when it was not so easy to find quality components (here in the communist Eastern European area).Were low-frequency bipolar transistors with low input impedance to the base, there was no risk of affecting the functionality of the circuit.But now it's easy to find quality components at great prices.
You can try to recycle a transistor with broken pins, with great care, a firm hand and patience. Use thin wire, don't overheat and clean the area very well with isopropyl alcohol, the input impedance to the gate is very high, there is a risk of making the noise worse.
Experimentation is part of the joys of DIY
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The reason is, I tried to find 2SK30A on ebay, and most of them are in China...IDK if they are real, or fake. When checking IDSS, what am I looking for?
RF parts, shipping is $15 dollars! Yikes.
Audio FREQ
What does your tester indicate for other jFETs eg 2N3819?
K30 appear to be fake jFETs.
The positive side is that you managed to repair the damaged transistor.
What does your tester indicate for other jFETs eg 2N3819?
K30 appear to be fake jFETs.
The positive side is that you managed to repair the damaged transistor.
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AUDIO FREQ
Try to measure K30A from the broken microphone dc/dc converter
Try to measure K30A from the broken microphone dc/dc converter
I think it's the cheap chinese transistor tester. It's saying my JFETS are BJT and my BJT are resistors...
I use FNIRSI DSO-TC3, very useful for DIY.
Oscilloscope, multitester,
signal generator.
Excellent performance/price ratio. Of course together with other multimeters and software.
https://www.elektor.com/fnirsi-dso-tc3-3-in-1-oscilloscope-component-tester-signal-generator
