Garbage display on my watts up meter

netwarri0r

1 mW
Joined
Sep 16, 2014
Messages
10
Hi, i have a watts up meter for just 3 months now and i only use it for testing the voltage and capacity of my batteries. Now it just suddenly display garbage on the screen. It's very hard to read the display. Anyone knows how to repair it?
 

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netwarri0r said:
Hi, i have a watts up meter for just 3 months now and i only use it for testing the voltage and capacity of my batteries. Now it just suddenly display garbage on the screen. It's very hard to read the display. Anyone knows how to repair it?


This is just the 1602 LCD display that is scrap or have bad contact with the main board.

Doc
 
you could see if there is any cracked solder in the display connector, and reflow it at both lcd side and main board side.

other than that, it could be either in the mcu or lcd. i had one trashed display like that but never got to figuring out what was wrong. i don't think i have it anymore cuz i lost a lot of projects-to-be like that almost two years ago.
 
Thanks. I hope it really is just lcd with bad contact to the main board, that's easy to repair. But i cant open the casing, there is no screw.
Also, the screen doesn't show anymore like the screen on the second pic. It always show now like on the first pic. I really hope it's just bad contact.
 
AFAICR the WU case is ultrasonically welded together, and has to be cut open. On mine I carefully slit it with a utility knife blade on one long side, then opened like a clamshell breaking the far side.

Before you do that, you might check with the vendor and see what warranty they offer, to save you cost if the fix isn't that easy.
 
Already opened it. I can't see any bad solder joint.
I noticed that when the input voltage is low like 4.1v, i can get a display like on the 1st pic where you can see the numbers and the A and V and no display on the bottom row. If the input voltage is around 7v or higher the whole top row is full of dotted black.
I am thinking that i got a bad MCU?
 
I tried the reset connector on the auxiliary connector, now it shows like in the 2nd pic above. I can see the voltage and current but it's scrolling to the left. It also shows less current than the actual load. Like for example if the load current is 3A, i can see that the reading is 2.4A only. I guess it's the mcu that is failing.
 
Maybe it turned bad but i can only remember i connected it on wrong polarity the very first time i use it and that was fast, i immediately disconnected it. It's in the auxiliary connector for powering the meter.
 
netwarri0r said:
i connected it on wrong polarity the very first time i use it
If people would give ALL the detailed history of a device, system, or problem the first time around it'd be a lot easier to help. :/

Based on that, the problem is likely nothing to do with LCD or MCU, but is probably the voltage converter chip.

If you have a multimeter you can look up old threads about the Watts Up / WattsUp / WU and find at least partial schematics to see where to measure that, and what part number it is to replace it if it's bad.

It could just be a resistor on it's input, or even solder that melted partially at the time from the extreme overcurrent (one I had here that was sent to me broken had been hooked up backwards by it's original owner, and several parts were melted at least partly off the spots on the board they should've been on)
 
amberwolf said:
netwarri0r said:
i connected it on wrong polarity the very first time i use it
If people would give ALL the detailed history of a device, system, or problem the first time around it'd be a lot easier to help. :/

Well I thought that it has nothing to do with the wrong polarity because i thought that it has a reverse polarity protection. And it is still working 3 months after that, that's why i did not mention about that here.
I also have the cheaper GT power meter and i have connected it in wrong polarity many times and still working fine.
 
I connected the lcd display from my GT wattmeter to see if it will show the same screen as my watts up meter. What do you think, is it a bad mcu?
 

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