help about multimeter UNI-T UT58C - Page 1
Forum section: electronics / repair

author: BENAMORMED
author_rank: Newbie
timestamp: May 31, 2024, 04:53:07 am
content: hello at allafter wrong use the multimeter become unusablethe problem is: multimeter continous beeping on AC or DC and Ohmall musurement are falsebut work in diod mod/buzzerany help pleasethanks

author: Overspeed
author_rank: Frequent Contributor
timestamp: May 31, 2024, 06:45:53 am
content: HelloYou need first to open it and search possible burned components or pcb tracksRegardsOS

author: BENAMORMED
author_rank: Newbie
timestamp: May 31, 2024, 09:53:06 pm
content: hello evryone,thanks for replayi check the fuse is okdiode , zener diode okNo visual burned or damaged componentsee attached photosany suggestion for next step!thanks for all

author: Poroit
author_rank: Frequent Contributor
timestamp: June 02, 2024, 03:19:53 am
content: Did you apply AC Volts while the meter was on the Ohms Range?

author: BENAMORMED
author_rank: Newbie
timestamp: June 02, 2024, 09:20:24 pm
content: HelloIm not sure but may be yesThe buzzer work perfectly in beep mode when i connect the probeBut it beep constantly in the rest of range except the capacityAny idea!Thanks

author: Poroit
author_rank: Frequent Contributor
timestamp: June 03, 2024, 08:31:15 am
content: Most multimeters are damaged from users forgetting to switch ranges.The fuses don't react quickly enough to prevent component damage.If you were measuring Resistance and forgot to change ranges before measuring AC Volts then you have taken out a component in the Resistance network.Similarly if you had your multimeter set to measure DC current and attempted to measure AC Volts, then you will take out a component in the Universal current shunt.

author: Zenith
author_rank: Frequent Contributor
timestamp: June 03, 2024, 09:06:09 am
content: The schematic for the UT58A is available on Elektrotanya.https://elektrotanya.com/multimeter_ut58a_sch.pdf/download.html#dlI think there are only small differences between the UT58A, B and the UT58C, which you have. I couldn't find a service manual, but having the schematic for systematic fault finding is a lot better than trying to work things out without one.You didn't say what the abuse was. If it was applying mains voltage while on the resistance range, it could well have caused widespread damage, which may not be obvious.It's always worth investigating, because often faults are easily fixed, but I suspect you will have to buy a new meter.

author: BENAMORMED
author_rank: Newbie
timestamp: June 04, 2024, 01:51:58 pm
content: helloi check the part of buzzer ic 4011 and 358all the resistance are okno short in capacitor

author: alonsojar
author_rank: Contributor
timestamp: June 04, 2024, 09:39:15 pm
content: Did you check for faulty (shorted) PTC's?This is a common fail after misuse at least in flukes.Good luck in your repairJ Alonso

author: BENAMORMED
author_rank: Newbie
timestamp: June 05, 2024, 08:24:37 pm
content: helloyes it's ok no short

author: BENAMORMED
author_rank: Newbie
timestamp: June 05, 2024, 08:59:22 pm
content: hellogreen point no beepred point continous beep and fault mesurementgreen and red sometimes beep sometimes no beepcan any one help to resolve this problem

author: Poroit
author_rank: Frequent Contributor
timestamp: June 06, 2024, 08:06:20 am
content: How did you test LM358 & CD4011?Did you review component data sheets & measure signals on the various pins?

author: BENAMORMED
author_rank: Newbie
timestamp: June 06, 2024, 01:52:58 pm
content: How did you test LM358 & CD4011?Did you review component data sheets & measure signals on the various pins?no not yet only the component related to the IC 358 et 4011 (resistance and capacity marked in red) and short test in the Pins