Question about FET 2SK117 in old stereo receiver

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I have an old stereo receiver which has two FETs in preamplifier stage, they are 2SK117 and probably they doesn't work. I bought new 2sk117, but what I wish to know; original FET was 2sk117 GR and I have new 2SK117Y. The different between those two FETs is in IDSS,
Y has 1.2~3.0 mA, GR has 2.6~6.5 mA, BL has 6~14 mA.

So my question is, can I use this 2SK117 Y instead 2SK117 GR (Service manual recommended to use 2SK117 GR or BL). What will be if I use that 2SK117Y ?

Regards!
 
Official Court Jester
Joined 2003
Paid Member
Zeljko said:
I have an old stereo receiver which has two FETs in preamplifier stage, they are 2SK117 and probably they doesn't work. I bought new 2sk117, but what I wish to know; original FET was 2sk117 GR and I have new 2SK117Y. The different between those two FETs is in IDSS,
Y has 1.2~3.0 mA, GR has 2.6~6.5 mA, BL has 6~14 mA.

So my question is, can I use this 2SK117 Y instead 2SK117 GR (Service manual recommended to use 2SK117 GR or BL). What will be if I use that 2SK117Y ?

Regards!


1. mebbe it will work ok
2. mebbe it will sound sound distorted
3. mebbe it will go puf


just try them
 
EUVL said:

But it will make life much easier if you have the schematics.


Patrick

OK, here it is...

Regards!
 

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Are you sure the old ones are bad? They aren't known for failure...

One part on your schematic IS known for high-failure...D1 and D2, the VD1212 diodes. They can be replaced with a simple series pair of 1N4148 diodes. If you're having problems with that part of the preamp, get rid of the VD1212 diodes first. Every time I find them, I pull them out.

...looks like a Sansui something-or-other...:clown:
 
EchoWars said:
Are you sure the old ones are bad? They aren't known for failure...

I am thinking that someone has connected DVD Player or CD player on that Phono input…



Originally posted by EchoWars
One part on your schematic IS known for high-failure...D1 and D2, the VD1212 diodes. They can be replaced with a simple series pair of 1N4148 diodes. If you're having problems with that part of the preamp, get rid of the VD1212 diodes first. Every time I find them, I pull them out.
I checked those two diodes by digital multimeter, and they are good.

Originally posted by EchoWars
...looks like a Sansui something-or-other...:clown:
Yes, it is Sansui receiver :)
What's new on AK ;) ?

Regards!
 
Zeljko said:
I checked those two diodes by digital multimeter, and they are good.
Well, they nearly always check out fine with the tiny current that a meter puts through them.

I'm not sure that feeding the phono input with a CD player would kill it. I don't think it would have sounded very good, but it really should not blow up the phono stage.

Is the phono dead? Or just sound bad?
 
EchoWars said:
Well, they nearly always check out fine with the tiny current that a meter puts through them.

On what better way I can check this diode?

EchoWars said:
I'm not sure that feeding the phono input with a CD player would kill it. I don't think it would have sounded very good, but it really should not blow up the phono stage.

Is the phono dead? Or just sound bad?

I got this receiver in very bad condition, and both channels on this phono stage are dead. I bought in local store some 2SK117 but not BR or GR, just only Y (as I written before different is only in IDSS). So, what will be if I replace that original with this Y FETs? Can it work for a long time, if it will work?

Regards!
 
Zen Mod said it...just replace them. Not worth wasting time on them.

As far as the phono not workng, sounds to me like you're replacing transistors without knowing why. Attack this problem with a little bit of logic and some old-fashioned troubleshooting methods. Measure some voltages and see what the transistors are doing.
 
EchoWars said:


As far as the phono not workng, sounds to me like you're replacing transistors without knowing why. Attack this problem with a little bit of logic and some old-fashioned troubleshooting methods. Measure some voltages and see what the transistors are doing.

Echo, I checked transistors and those diodes, and it seems to me they are good. My logic told me that maybe it is problem with those FETs. So because they aren't expensive, I bought some of them to replace, but I am wondering do they work because of lower IDSS. But OK, I will replace them and see what will happen.

Regards!
 
Official Court Jester
Joined 2003
Paid Member
Zeljko said:

Does it means, every time when I found VD1212 diodes, I need to replace them :confused: ??

Regards!


depends;

but- if you are in sort of repair beeezneeeesss , you'll find some techniques as fastest and less troublesome .

replacing crummy old parts, (elcos ,for instance) then became just routine ;
remember- time involved in any repair is often of much bigger value than parts price
 
Zen Mod said:



depends;

but- if you are in sort of repair beeezneeeesss , you'll find some techniques as fastest and less troublesome .

replacing crummy old parts, (elcos ,for instance) then became just routine ;
remember- time involved in any repair is often of much bigger value than parts price

I am not really repair service, I am doing restoring old Sansui receivers, amplifiers and tuners. Because of that I have so much originals NOS parts for Sansui devices and many original Service Manual.
When some part is dead, first I wish to buy a new original (because of that I am asking you about those 2SK117, I wish to know can I replace BL or GR with Y in future too, if I need to replace some of them) I know about elcos look my web sites:
- Restoring G7000
- Restoring G5000

Regards!
 
Netlist said:
I was just about going to point you to the most obvious: fuses and voltage rails.
Since you seem to know your stuff, discard this post unless you really didn't check them. :)

/Hugo
Thank you Hugo, but what is strange, all voltage test points show me correct voltage (OK with small difference in value from value in SM, but this is normal), and this phono stage doesn't work, I have characteristic noise from it but not sound :confused:
Now I dont have some free time to replace those 2SK117, but I will tomorrow, and I will post here the results.

Regards!
 
Official Court Jester
Joined 2003
Paid Member
Zeljko said:


I am not really repair service, I am doing restoring old Sansui receivers, amplifiers and tuners. Because of that I have so much originals NOS parts for Sansui devices and many original Service Manual.
When some part is dead, first I wish to buy a new original (because of that I am asking you about those 2SK117, I wish to know can I replace BL or GR with Y in future too, if I need to replace some of them) I know about elcos look my web sites:
- Restoring G7000
- Restoring G5000

Regards!


OK- good to know....... ;)

anyway- you must find a way to calc working parameters of 2sk117 from schematics or actual circuit; then you'll know can you put Y part in it,thinking about Iq and max input swing on jfet's gate.

you need 2sk117 pdf data , and that will tell you everything you need to know .
In case that you don't know how to calc this,it's handy- for future , to learn.

there are few ways to find out are these jfets in your actual circuit working or not; just measure current through R9 and R11

as I see it- you must have 2mA through each jfet ; well worth at least trying to put Ys in place and try it. they will not be burned; worse thing can happen is distortion . but- in that case you'll at least know are these original jfets defective or not.

just power your iron and brain, don't waste time on typing
 
Zen Mod said:



OK- good to know....... ;)

anyway- you must find a way to calc working parameters of 2sk117 from schematics or actual circuit; then you'll know can you put Y part in it,thinking about Iq and max input swing on jfet's gate.

you need 2sk117 pdf data , and that will tell you everything you need to know .
In case that you don't know how to calc this,it's handy- for future , to learn.

OK, here it is datasheet :D

Zen Mod said:
there are few ways to find out are these jfets in your actual circuit working or not; just measure current through R9 and R11

as I see it- you must have 2mA through each jfet ; well worth at least trying to put Ys in place and try it. they will not be burned; worse thing can happen is distortion . but- in that case you'll at least know are these original jfets defective or not.

I am not so good with testing FET transistors, so this advice is so good for me. If I am not sure what to do, I rather ask before doing something!! Thank you! :up:

Originally posted by Zen Mod just power your iron and brain, don't waste time on typing [/B]

But today is Sunday, its nonworking day :) !

Regards!
 
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