Shannon ST42 LCR Tweezer Test and Comparison Thread

[KungFuJosh]

I was curious so I threw the SMT fixture on my ST2832. Wasn't much difference between Cp/Cs there either. I didn't do more than a few minutes warmup, so take the final value with a microscopic grain of salt.

[Martin72]

With 2V bias (according to the display)?
It doesn't matter, you could now take 100kHz, because according to the data sheet values up to 1pF were tested with 1Mhz (interestingly from 1pF with 1kHz...).
But this is only of academic interest, because the fact that the tolerance of the 1pF is given as 0.25pF shows how difficult it is to determine the actual value.
I therefore think that both LCRs have roughly the same idea of "where" the capacitor is in terms of value (Yeah, Heisenberg).

[mawyatt]

I was curious so I threw the SMT fixture on my ST2832. Wasn't much difference between Cp/Cs there either. I didn't do more than a few minutes warmup, so take the final value with a microscopic grain of salt.

With Series and Parallel equivalents, if Rp is >> 1/W*Cp, then Cs ~ Cp, or if Rs << than 1/W*Cs, then Cp ~ Cs.

BTW wrt your "Enhancement" of the original TH2830 to the ST2832, noted the DC Bias at 2V on the display. Did this come with the "Enhancement" ?? Maybe post on the TH2830 thread rather than divert this one.

Best

[KungFuJosh]

I'll respond here since it's relevant to the discussion.

Yes, the bias option came with the improvement.

But no, the 2V bias is not active in those tests. That's just showing what it's set to. There's a physical button that determines whether or not bias is active. It's a shame they didn't think to note active status on the screen.

I'll hopefully remember to set that to zero for future tests to avoid confusion.

ETA: I tested at 350mV and 10kHz to match the ST42.

[mawyatt]

@ Josh,

Recall you had issues with some range(s) and/or frequency(s) after the "Enhancement"?

Need to go to that thread if I can find it wrt the issues.

Best,

[KungFuJosh]

@ Josh,

Recall you had issues with some range(s) and/or frequency(s) after the "Enhancement"?

Need to go to that thread if I can find it wrt the issues.

Everything was resolved eventually with some firmware updates. Which was funny. TH told ST that they already had the latest fw. So I sent ST photos of another EEVblogger's newer firmware version. That helped ST get better fw from TH, and everything has been great since then. Our antics helped ST out pretty well I'd say. 😉

You can see my test attached to this post: https://www.eevblog.com/forum/testgear/shannon-st42-lcr-tweezer-test-and-comparison-thread/msg5561319/#msg5561319

The attached PDF in that post has the full results, and everything looked good. The only issue with the comparison was, as you pointed out, my test voltages weren't matched. That's why I switched the ST2832 to 350mVrms after to get closer to the 1Vpp of the ST42. Overall, matching was really good anyway except for those few spots where the testing voltage really mattered.

That PDF has my version of all the cal testing that was done on Martin's ST2830.

Thanks,
Josh

ETA:
Here's the LCR thread: https://www.eevblog.com/forum/testgear/th2830-vs-th2832/
This thread is relevant too: https://www.eevblog.com/forum/testgear/lcr-cal-test-pcb/

[KungFuJosh]

1.5.5. from May2024

I ran the OTA update again, and now I have 1.5.6. Shows Cp/Cs now. Sweeet.

[Martin72]

I ran the OTA update again, and now I have 1.5.6.

Where do you get it from?

[KungFuJosh]

I ran the OTA update again, and now I have 1.5.6.

Where do you get it from?

This page: https://shannontweezers.top/docs/upgrading-firmware/

Has this link: https://github.com/shannontweezers/shannontweezers.github.io/releases/download/2023-5-10/fw-update-2023-5-10.zip

Download and run from a terminal prompt. You do updatername.exe com5 or whatever your com port is. I renamed the updater fwu.exe cause I don't like typing extra BS.

To get into update mode, you leave the ST42 off, then push the joystick one direction (up or down, I forget which) then plug in the USB cable and it should enter the update mode. If it starts up and shows you charging info, it didn't work.

[unmaker]

I was wondering why the latest firmware on Shannon's page is 1.5.3. Are there firmware release notes for the later firmwares?

[Martin72]

Hi,

To get into update mode, you leave the ST42 off, then push the joystick one direction (up or down, I forget which) then plug in the USB cable and it should enter the update mode.

Joystick up....
Now I got 1.5.6. too. 

[KungFuJosh]

I was wondering why the latest firmware on Shannon's page is 1.5.3. Are there firmware release notes for the later firmwares?

He's super slow to update anything on his website, but he does make stuff available faster with the OTA updates.

One thing we know is the newer version says Cp/Cs instead of guessing. 😉

[Martin72]

The devil is in the detail.....
I thought to myself, now you're going to make something nice to rebuild, something that has hands and feet and extends the tweezers - why don't you make adapter cables with test hooks so that you can also test large components.
No sooner said than done, it hardly costs anything, looks good and fits perfectly.
If it weren't for one tiny little pitfall.
After attaching the cables, the ST42 shows short circuits everywhere - why...
Quite simply, the small screws must be screwed in insulated, because of the Kelvin functionality....Cool.
Never mind, just make the holes in the blades a bit bigger - or use an original set of blades from Shannon.
Either way, I think this is the more “professional” solution to extend the tweezers instead of just wrapping wire around them.
I will present the final solution soon.

[KungFuJosh]

Very nice! That is a cool idea.

[Martin72]

Do you know where to get “spare parts”?
So the blades, screws and the insulation sleeves...
I googled it and ended up with Ali - but then again with the complete tweezers.

[tautech]

Do you know where to get “spare parts”?
So the blades, screws and the insulation sleeves...

Depending on which version of ST42 you ordered, you should have all these already.
Remove the box foam lining and check what's underneath.

[KungFuJosh]

Do you know where to get “spare parts”?
So the blades, screws and the insulation sleeves...
I googled it and ended up with Ali - but then again with the complete tweezers.

You can email Shannon directly and ask. Sometimes the Ali ad has spare tips separately also.

[tautech]

Select: Curved Tips Only......since you were a tight bugger when you purchased them. 
https://www.aliexpress.com/item/1005004239869204.html

[Martin72]

I paid just under €150, so you might expect them to have been included.
But they weren't.
Instead, I would now have to put down €25 for the tips only....Nice try, I'd rather drill larger ones in other tips.
The subject of spare parts is a purchase decision that should not be underestimated, addressed to the gentlemen who may be thinking about distribution.

In addition to the tips, the battery used comes to mind spontaneously and more importantly.
Is it replaceable? Is it a freely available standard type?
A potential distributor should also be able to provide information on this.
So screws, insulation, tips, battery.
With “You should have thought of it earlier and bought it at the same time” you won't get far in the favor of potential buyers.
Just a bit of advice.

[tautech]

I paid just under €150, so you might expect them to have been included.
But they weren't.

Of course.

Instead had you selected Color: ST42 TestBrd CurvTip from the BUY options you would have the curved tips, screws and bushes too.

The most expensive option includes the pouch also and is: ST42 TBrd LeCas Tips

[TomKatt]

Whelp, now I see that plastic bead thing must be the screw insulator…. I posted earlier about opening my tweezers box in the car after retrieving it from the post and must have lost 1 of the insulators (reply #37)…. If it was in the box, it must have been loose - tiny parts like that should really have been packaged in a bag or something…

Edit - I ordered the curved tips option.  Anyone know where I can obtain another insulator?

[KungFuJosh]

Whelp, now I see that plastic bead thing must be the screw insulator…. I posted earlier about opening my tweezers box in the car after retrieving it from the post and must have lost 1 of the insulators (reply #37)…. If it was in the box, it must have been loose - tiny parts like that should really have been packaged in a bag or something…

Edit - I ordered the curved tips option.  Anyone know where I can obtain another insulator?

Email Shannon and ask him to include it with your new tips.