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Electronics => Repair => Topic started by: ganteng on October 09, 2020, 08:08:04 am

Title: UT71D
Post by: ganteng on October 09, 2020, 08:08:04 am
My UT71D is error on display
but if i sellect SETUP..the display is OK
but if i select any mode the display has error

any suggest for my problem?
i'll try to write the bios rom but i don't have it
anyone have it?

maybe can help for my UT71D problem
Title: Re: UT71D
Post by: tkamiya on October 09, 2020, 06:24:51 pm
I'd try fresh batteries....

After that, I'd open that up and see if there is anything obvious going on, like corroded connections, burned components, etc.  It was working for you for a while and now it's not, or is this a new purchase?
Title: Re: UT71D
Post by: MosherIV on October 09, 2020, 09:34:09 pm
Some dmm have test mode to test lcd, just keeps all characters on.
Usually enabled by pressing a certain button when turning on.

So maybe, one of the buttons is stuck on.
Title: Re: UT71D
Post by: Jasonbit on October 09, 2020, 10:20:51 pm
Hello,

Maybe on this webiste you can find what you need to solve the issue (https://www.uni-trend.com/html/product/General_Meters/Digital_Multimeters/UT71_Series/UT71D.html (https://www.uni-trend.com/html/product/General_Meters/Digital_Multimeters/UT71_Series/UT71D.html)).
The error on display does any code appear? Maybe share this issue with manufacturer can help.

Maybe you can compare your equipment with this need equipment, on video (https://www.youtube.com/watch?v=qi_tBbehw-4 (https://www.youtube.com/watch?v=qi_tBbehw-4))
Title: Re: UT71D
Post by: ambrosia heart on October 10, 2020, 01:49:46 am
any suggest for my problem?
i'll try to write the bios rom but i don't have it
anyone have it?

See photo.  If I2C paths signal ACK( communication signal ) is OK, Bios is needed.  :popcorn:
 If you don‘t know  what I am talking about,  just let it be.[attachurl=1]
Title: Re: UT71D
Post by: ganteng on October 10, 2020, 03:20:27 am
any have bios?
Title: Re: UT71D
Post by: Mickle T. on October 10, 2020, 05:43:04 am
M430F149 firmware is protected. You will never get it.

I think the problem is a bad ADC.
Title: Re: UT71D
Post by: rsjsouza on October 10, 2020, 11:17:33 am
Quote from: MosherIV on October 09, 2020, 09:34:09 pm
So maybe, one of the buttons is stuck on.
Given the state of the meter (did it fall into a pool of mud?) I would open it and perform a thorough cleanup of the board, especially around the rotary switch and around the main IC.

And yes, the main IC has internal flash and is protected.
Title: Re: UT71D
Post by: payn on July 19, 2023, 05:30:44 am
Had same problem.
The copper track at the top(top of meter) of the 4MHz crystal had broken just after where it comes trough the board and attaches to the crystal. If I applied a little pressure to the crystal the meter came back to life, however as soon as I released the pressure the fault returned.
Difficult to reuse the smd crystal so I replaced the 3.999FSHM with 4MHz one, trimming legs so that they could be soldered to what was left of the through board copper track.