UT61E vs Ionizer

[hgg]

Hi,

This was my first try to make a 15 stage ionizer and I had the brilliant
idea to use my UT61E to debug it.  A probe on the wrong component
and after a tiny flash the UT61E was zapped to oblivion...    I don't care
about the meter itself as much as the work I've done for all the upgrades
it has.  So any help would be much appreciated! 

The Killer :


The "new" selection modes after the zapping :





I've tried to see if there was anything obvious on the board but there is not.
If you look at the photo below diodes D5 & D6 measure dead short in either direction
and the double diode D4 has a voltage drop of 0.1V in either direction as well.
(meter was in off position).

Is this normal?  Looks like that these diodes are dead.  What do you think?
The meter works correctly only in capacitance and Amperes mode.

I hope there was no damage on the main chip ES51922.
Can you please help me track down the problem?
Thank you!




Schematic :

[001]

Nice photos 

Check Q5&Q6 and MOVs

Use 990M resistor serial  with Your meter next time and multiply readings x10

[Wolfgang]

I would say its time to say farewell. R.I.P, Uni-T . Maybe a 87V next time

[joeqsmith]

There isn't much to these meters.  The fact that the FC pins are no longer working tells me the main IC has a problem.  It may be difficult to source a replacement.   

I've damaged a few of these.  They are not the most robust of meters.  Actually, pretty low on the scale compared with the others I have looked at.   Still, hard to say if a top of the line meter would have survived the same mistake. 

[hgg]

Indeed they are not, although the applied voltage was many KV.
D5 and D6 are actually ok.  There is a 9 Ohms resistor across.

I removed the switching double diode D4 and one of the internal
diodes was shorted.  Maybe there is a chance that the IC survived.

I will order a replacement diode and see what happens.   

[hgg]

I will have the replacement diode next Tuesday.

The meter works fine in Hz, A and Capacitance modes.
D4 controls the FC1 & FC4 lines and if you have a look at the table below you can see
that these are the modes when FC1 & FC4 are zero.  Would the above behavior be
normal when one of the diodes inside D4 is shorted?

[joeqsmith]

You could try a couple of switching diodes easy enough just to see.     

[hgg]

I'll give it a try.

[stj]

I would say its time to say farewell. R.I.P, Uni-T . Maybe a 87V next time

i knew some fanboy would say that!
next you will say the fluke would have given the correct voltage, even in "ohms" range with the probes in the current-jacks! 

[cdev]

Somebody else did exactly the same thing - as I remember reading it, some years ago..

posted here in some older thread.

Hi,

This was my first try to make a 15 stage ionizer and I had the brilliant
idea to use my UT61E to debug it.  A probe on the wrong component
and after a tiny flash the UT61E was zapped to oblivion...    I don't care
about the meter itself as much as the work I've done for all the upgrades
it has.  So any help would be much appreciated! 

The Killer :


The "new" selection modes after the zapping :





I've tried to see if there was anything obvious on the board but there is not.
If you look at the photo below diodes D5 & D6 measure dead short in either direction
and the double diode D4 has a voltage drop of 0.1V in either direction as well.
(meter was in off position).

Is this normal?  Looks like that these diodes are dead.  What do you think?
The meter works correctly only in capacitance and Amperes mode.

I hope there was no damage on the main chip ES51922.
Can you please help me track down the problem?
Thank you!




Schematic :

[hgg]

Do you remember what happened?
Dead UT61E ?

[cdev]

No but it was here that I saw it and I suspect the word 'ionizer' was also used. Or something close to it.

[nickeevblog10]

 Just out of interest and I do like posting this experience with the UNI-T 61E, after dismantling and reassembling then using the meter i was getting unusual readings. I found the ribbon around the readout LCD? was not wrapped perfectly around the edges of all the four sides of the display. It did take a bit of doing but eventually getting the ribbon back into place and readouts became normal. Do check this, for me a newbie this was great news.
The other problem I had with digital multi meter readers is using a meter that did not, not sure how to describe this, would not OL automatically but the UNI-T 61E does OL automatically. I did not need the UNI-T 61E (lol) but i like it with no mods.

[Wolfgang]

In fact I have UNI-Ts  *and* Flukes. While I had to fix the UNI-Ts several times, the only think I ever changed on a Fluke was a fuse.

[cdev]

I really like my UT-61E so I think that if I broke it I would try to exhaust all the possibilities to see if it was fixable and fix it if possible, before tossing it out.

I make it a practice of trying to fix things that break and even if I am not successful, I always learn something.

[Wolfgang]

I would say its time to say farewell. R.I.P, Uni-T . Maybe a 87V next time

i knew some fanboy would say that!
next you will say the fluke would have given the correct voltage, even in "ohms" range with the probes in the current-jacks! 

With a Fluke, its worth a try. 

[Electro Detective]

LOL, here we go, the gents are at it again...   


Sad news there hgg    what kind of zappage can one expect from an ionizer circuit?

Fanboy BS aside, as a Fluke owner user I'm confident the 87V would have got (eventually) zapped just as well as the UT61E,
but with a replacement 10x price tag for the adventure 

Good luck with the repair/s or if no go, you'll have spare parts on hand if you buy another UT61E.. or two..

...Use 990M resistor serial  with Your meter next time and multiply readings x10

multiply x10 or x100 ? 

Good advice, I use a 90M chain, next one will be a 990M 'upgrade' to be sure 

 

[NiHaoMike]

I've damaged a few of these.  They are not the most robust of meters.  Actually, pretty low on the scale compared with the others I have looked at.   Still, hard to say if a top of the line meter would have survived the same mistake. 

It's just 10kV with little energy behind it, basically ESD. Didn't several low cost Flukes survive 15kV with a very substantial amount of energy behind it?

[001]

Waiting for someone to post the graphic video of a tech guy probed 2.3kV with an 87-III and killed himself from the arc.

Is it Joke?
1000V CAT IV is rated for 6kV impulse 

[joeqsmith]

I've damaged a few of these.  They are not the most robust of meters.  Actually, pretty low on the scale compared with the others I have looked at.   Still, hard to say if a top of the line meter would have survived the same mistake. 

It's just 10kV with little energy behind it, basically ESD. Didn't several low cost Flukes survive 15kV with a very substantial amount of energy behind it?

I have lost a fair number of UNI-T meters to a piezo gas grill ignitor.   After so many UNI-T fan boys complained about the grill starter, I decided they were right and built the gun I now use.   Hard to say what the OP's 61E was exposed to.   It could very well be worse than the standard calls for.   I can tell you that I can zap myself with the grill starter and on a pain scale of 1-10, I give it a 1.  The gun I made is maybe a 2.  When I tested the Fluke  T6 with my hand in the circuit, I give that a 4. 

The first 10 minutes of this video I talk about ESD. 

https://youtu.be/1kYcY2ogmqo

Testing the T6 with my hand because I heard on the internet it would kill me.....
https://youtu.be/k8hhtTtWfVc?t=2634

[Nusa]

Waiting for someone to post the graphic video of a tech guy probed 2.3kV with an 87-III and killed himself from the arc.

Is it Joke?
1000V CAT IV is rated for 6kV impulse 

A Fluke 87-III is only a CAT III meter, last time I checked.
Also what blueskull said.

[001]

Ok
How  to live now?

[hgg]

I've connected 2 diodes together in place of the double package.
It looks like the IC internal pull up resistors are messed up.

I've also connected two pots from ground to FC1 and FC4 and
after some fiddling I've manage to show all the selection ranges
in the correct order but Volts mVolts and Ohms do not work
properly.  The pots were at approximately 48Ohms.

Any ideas?  Is it dead? 

[hgg]

Zero is -3.0V and One is floating around -100.0mV
In all modes except mV, Hz and Amps FC4 and FC1 lines show -2.5V or -1.5V instead of -3.0V
How can I find the values of the pull up resistors that the IC needs?

I am preparing the garbage bin with a new plastic bag...

[stj]

all the resistors have the values on them - just check everything.

btw,
on another forum there was a guy with a fence-charger.
he "tested" it with a fluke87 and killed it - no surprise really.
if you can kick a cow over a mile from the device via damp soil and a fence the energy must be pretty nasty.

what was funny, he then "tested" it with a uni-t mini meter and it displayed 3KV!!!!
i dont know if that was the true voltage but it didnt kill the meter