Half my J201s are bad?

[p_wats]

Long story short, it looks like half my through-hole J201s are bad. Short story long:

I was troubleshooting my in-progress Low Tide build, as it had farty, distorted output, which pointed to one of the JFETs. I assumed I had done a poor job soldering the surface mount 2Sk208, but my audio probe pointed to the through-hole J201 at the output stage. This was the first build that I didn't use sockets for the transistors, so it serves me right. Added a socket in that spot and swapped the J201, but it turns out only half of the ones in my stash actually sound right---the rest all have low output and sound farty and distorted.

I think they were mostly from Tayda over the years, but recall consolidating 2 batches into one bag at some point, so who knows.

In the attached photo the one on the left is bad and the one on the right is good (at least, it sounds good). Anyone else ever come across this?

 

[p_wats]

Are you sure about this 0.100mA? Maybe it was 100mV (0.100V)? That would be 1mA. I have some fake J201s with Vp around 1.4V and Idss around 1mA.

Hmm, that would make more sense, but is it likely Tayda was providing fake J201s in 2012? And if they are fake, what are they really? As they still seem to work fine in most circuits I've been trying them in aside from the Low Tide (which has no bias trimmer).

I'll have to re-measure. I also need to get a new 9v battery---I assume higher/lower voltage power would skew the results?

 

[temol]

Simple setup for a breadboard.

Vp


Idss

 

[p_wats]

Simple setup for a breadboard.

Thanks!

Hmm. I must be doing something wrong or my DMM is acting up.

I still get about 1.18v for VP but can't get a reading for Idss (changed my DMM to mA)

Going back to the prior vero layout, I get 1.08v and 97.7mV

 

[temol]

So 1.18V and 0.97mA. Within a specs, but on a higher side. For me, tht J201 immediately turns on the red light ...

 

[p_wats]

So 1.18V and 0.97mA. Within a specs, but on a higher side. For me, tht J201 immediately turns on the red light ...

I think I'm just going to go through them all and assume the ones that measure off are fake. I'll audition them when it's not crucial, but otherwise pick up some SMD versions to sub in going forward.

Already spent too much time on these! Thanks for the help.