UNI-T 61D Defective voltage - Page 1
Forum section: electronics / testgear

author: Auklend
author_rank: Newbie
timestamp: July 18, 2015, 02:51:21 pm
content: My UNI-T 61D woun't read voltage.I was playing with it, an tried to measure the voltage in a ingition electrode.Any suggestions on what to do? Is it repairable? I have replaced the 1A Fuse, which was not the problem. The fuse was working.It looks like this in voltage mode.

author: SeanB
author_rank: Super Contributor
timestamp: July 18, 2015, 03:11:11 pm
content: Save for a new one, you cooked the main chip input side...........

author: Auklend
author_rank: Newbie
timestamp: July 18, 2015, 03:19:32 pm
content: Thought so. No burned parts inside.

author: max666
author_rank: Frequent Contributor
timestamp: July 18, 2015, 03:21:14 pm
content: Don't know what input protection the UNI-T 61D has, but SeanB may be right and you fried the chip. What kind of ignition electrode are we talking? Car?

author: Auklend
author_rank: Newbie
timestamp: July 18, 2015, 04:02:49 pm
content: Those for ingiting gas refrigerators/stoves.Thanks for the video.

author: mcinque
author_rank: Unknown
timestamp: July 18, 2015, 04:41:44 pm
content: Like a piezo/electronic spark igniter???

author: saturation
author_rank: Super Contributor
timestamp: July 18, 2015, 04:46:40 pm
content: Is the rest of the DMM functions still working? Current? Ohms in particular? If so, it suggests the CPU is still working. The output of an ignition coil is in kV and likely tripped the input protection circuits, see green squre. Visually inspect them, if blown, you can bypass them and see if the meter starts up. MOV's fail open, but if they shorted you'd have to cut a lead to open them, and if the series PTC resistors opened you'd have to short across them. If the input protection failed to act quick enough the meter may still not act right, it could blow additional components, typically signal diodes or input transistors, e.g. green arrows. Visually inspect those, they are less easy to repair and if damaged, it could have also damaged the input to the main IC, so recovering your meter is less likely.

author: Lightages
author_rank: Unknown
timestamp: July 18, 2015, 09:12:39 pm
content: I would look for a new meter. Multimeters are not meant to measure voltages used for spark ignition. You are trying to measure 10s of kilovolts and they are not designed to withstand that, no matter what brand.If you want to stay with Uni-T, I suggest you look at the UT139C at $50. There is also the Amprobe AM5X0 series which are good for low prices. Of course there is the Brymen BM257s for $135 shipped to you. There are many options but not all are worth buying.

author: mcinque
author_rank: Unknown
timestamp: July 18, 2015, 09:14:09 pm
content: Quote from: joeqsmith on July 18, 2015, 08:55:07 pmQuote from: Lightages on July 18, 2015, 09:12:39 pmI think he used another kind of igniter:Quote from: Auklend on July 18, 2015, 04:02:49 pmlike a piezo or electronic BBQ igniter. Of course that doesn't change the fact that they also can easily fry the DMM.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 19, 2015, 12:05:00 am
content: Hitting the Fluke 101 with transients from a piezo grill starter.

author: max666
author_rank: Frequent Contributor
timestamp: July 19, 2015, 02:24:50 am
content: You didn't waste any time going at this, did you Joe?I too would have thought that some simple MOVs and some diode clamping would save most meters from a piezo igniter, but the fact that Auklend's meter now shows kOhm in the display while in voltage mode doesn't look promising to me.

author: Fungus
author_rank: Super Contributor
timestamp: July 20, 2015, 10:29:22 pm
content: Quote from: saturation on July 18, 2015, 04:46:40 pmIt's showing Ohms when the switch is on CD volts range...I'm guessing "not".

author: Fungus
author_rank: Super Contributor
timestamp: July 20, 2015, 10:30:22 pm
content: Quote from: joeqsmith on July 18, 2015, 08:55:07 pmIs the 101 the new standard?

author: joeqsmith
author_rank: Super Contributor
timestamp: July 20, 2015, 10:46:55 pm
content: Quote from: Fungus on July 20, 2015, 10:30:22 pmYou sir, should have never set the bar so high and get so many Fluke users upset! I guess I was supposed to treat that 87V with more care and respect than I did.Until a company steps up and makes a more robust meter than this $50 cheapo, your 101 remains the meter to beat!

author: saturation
author_rank: Super Contributor
timestamp: July 22, 2015, 11:01:22 am
content: Off topic: Thanks to your impressive thread I've obtained a 101 and running it through more tests.Quote from: joeqsmith on July 19, 2015, 12:05:00 am

author: joeqsmith
author_rank: Super Contributor
timestamp: July 23, 2015, 02:21:42 am
content: Quote from: saturation on July 22, 2015, 11:01:22 amLooking forward to seeing what tests you come up with for it. Maybe a new thread, "The Fluke 101, Tougher Than...."Klein Tools would be all over that!

author: saturation
author_rank: Super Contributor
timestamp: July 24, 2015, 12:47:04 pm
content: Off topic: quick test on the Fluke 101 via temp testing, from 11oF to 140oF, that's what the temperature ended up to be. Leaving unit in freezer for 1 hour, functional test for 5 min, oven for an hour then function test, both back to back for 'temperature shock'. The meter stays within printed spec. Those temp ranges are beyond the 0o-40oC [32oF-104oF] operational range in the printed spec.Quote from: joeqsmith on July 23, 2015, 02:21:42 am