U1273A - Page 1
Forum section: electronics / repair

author: edmundopt
author_rank: Regular Contributor
timestamp: December 01, 2017, 05:48:02 pm
content: Himy multimeter is malfunctioning, is out of warranty and according to Keysight reply I must send it to the place where I purchase it from.I am going to do some measuring first, maybe I can have a better understanding of what failedafter some search, most of topics are buy/sell/firmware update failhere is a small video with the issue :https://youtu.be/VHRyUSdh95Q( its not listed and it can only be accessed from this link)as you can see in Volts/miliVolts range almost all functions are available, you can not however get into the menuOhms range and capacitance do not work, better watch videoI am asking for help where to start measuring it

author: Samogon
author_rank: Frequent Contributor
timestamp: December 02, 2017, 07:29:33 am
content: Is there dirty key contacts and rotary switch or it is shades on the picture? Dirty contacts can play wierd games with meter.

author: edmundopt
author_rank: Regular Contributor
timestamp: December 02, 2017, 07:05:42 pm
content: I have cleaned them all, including keyboardI've uploaded new pictures without flashI connected bluetooth unit, so the meter recognizes position : 3; 4; 5; 7; 9; 10so, something is wrong with it recognizing the position 1 2 and 6, wich are the ones that are really badany idea what is the chip that provides info to the controler of the rotary position ?

author: Samogon
author_rank: Frequent Contributor
timestamp: December 02, 2017, 07:45:24 pm
content: Usually it is MUX/DEMUX chip like BU4051 or similar

author: Samogon
author_rank: Frequent Contributor
timestamp: December 02, 2017, 07:57:50 pm
content: I have same meter and love it, may be i open it to see what inside and make reference measurements.

author: saturation
author_rank: Super Contributor
timestamp: December 02, 2017, 10:09:36 pm
content: How did the meter fail? Did the meter malfunction spontaneously ? Were you measuring line voltage at the time?

author: edmundopt
author_rank: Regular Contributor
timestamp: December 02, 2017, 11:51:56 pm
content: Quote from: saturation on December 02, 2017, 10:09:36 pmThis is my bench multimeter, 100% of its job is in ohms/milivolts measuring battery(3.3, 5v, sometimes 12) powered devices, never touched linebattery was low, it auto turned off, I put new fresh batteries and that was it, it was all over the place.going to search for the chip and maybe reverse engineer the path to it

author: Samogon
author_rank: Frequent Contributor
timestamp: December 03, 2017, 12:12:32 am
content: Hmm looks like FW glitchTry set it to default via setup menu

author: edmundopt
author_rank: Regular Contributor
timestamp: December 03, 2017, 03:10:26 am
content: Quote from: Samogon on December 03, 2017, 12:12:32 amFirst thing I tried to do, but look at me pressing setup buton for more then 1sec, it beeps but it does not get in, in any range.I searched the board for a hard reset, can't find any, also via terminal (u1177a) the command is not known on "the internet" :/Enviado do meu LG-D855 através de Tapatalk

author: saturation
author_rank: Super Contributor
timestamp: December 03, 2017, 11:30:29 am
content: Ouch, this does sound like a firmware issue, either as a bug or hardware fault.The likely solution is reflashing the firmware if you can get to the menu, but if its a hardware fault then it may not be user repairable. Best of luck, sorry to hear.Quote from: edmundopt on December 02, 2017, 11:51:56 pm

author: Samogon
author_rank: Frequent Contributor
timestamp: December 03, 2017, 12:20:01 pm
content: Well, if FW is in the separate flash chip we potentially can write good FW.

author: Samogon
author_rank: Frequent Contributor
timestamp: December 03, 2017, 12:35:50 pm
content: Wait, do you have IR pc cable for it? If so download FW update ftom keysight site and try to refresh FW

author: edmundopt
author_rank: Regular Contributor
timestamp: December 04, 2017, 08:34:15 pm
content: because of the chance of completly bricking it due to firmware update fail, I will first complete the reverse engineering of how the microcontroler reads the rotary switch positionI should complete this today, and then I will update firwmare, or atempt to

author: Samogon
author_rank: Frequent Contributor
timestamp: December 05, 2017, 06:39:29 am
content: Sure it is your meter.