HomeWizard Energy Display (no backlite)

[kekelen]

Hi everyone,

I’m a total beginner at electronics repair and have very limited knowledge about components, so please bear with me.

Problem:
The display on my HomeWizard Energy unit started flickering for a few minutes and then went completely dark. The backlight no longer works, but I can still faintly see the text on the screen under good lighting.

I tested the display itself on a drive control board (used for PC/Raspberry Pi), and the screen works fine — so the issue seems to be on the main board.

What I’ve tried so far:

• Checked for shorted capacitors — none found.
• Looked for components getting hot — found one SMD “chip” that heats up quickly. I believe it’s a voltage regulator, but I can’t find a replacement for it.
• Measured the chip’s voltage and resistance (see attached picture).

Questions:

• Do these voltage/ohm readings look normal, or does it seem like the chip is faulty and needs replacing?
• Is there anything else I can test or measure that could explain why the backlight isn’t working?

Any help or advice would be greatly appreciated!

Thanks in advance,

[stj]

check D1,
get a part number off the display and find a datasheet to determin the led drive voltage.

[kekelen]

D1 both side's 4.9V
There’s nothing on the display—no numbers or stickers.
The only marking I found is on the ribbon cable: H5003B40.
However, I couldn’t find any information about it when searching on Google.

[nomoresonys]

So D1 is a diode, check it in diode mode. There aren't a ton of components so check all the resistors and capacitors, marked with letters R and C, youtube has many how to videos for checking them with multimeter. A simple diode check is with device unplugged from power, meter in diode mode, a probe on each end note reading, switch probes note reading.

[nomoresonys]

https://www.youtube.com/watch?v=VBskFOlzIAA&t=89s

[lotas]

U2- Kcxxx - RY3740CT5

[nomoresonys]

Here's some mlc capacitor testing (the little brown ones) I hope "you understand" https://www.youtube.com/watch?v=9Ceey-FIRuY

[kekelen]

I understand 😁

These are the readings I made, along with some screenshots of the resistor values.
Thank you for all the help — I’ve already learned a lot.

Capacitors

C1	0.2	92	OK
C2	0.2	92	OK
C3	0.2	92	OK
C4	0.2	OL	OK / open
C5	OL	OL	open both
C6	0.2	92	OK
C7	0.3	OL	OK / open
C8	0.3	OL	OK / open
C9	0.3	OL	OK / open
C10	0.2	OL	OK / open
C11	0.2	OL	OK / open
C12	0.3	OL	OK / open

Diode

D1	OL - 0.240

Resistors

R1	5.1 kΩ	OK (checked with app smd values)
R2	5.1 kΩ	OK
R3	143 kΩ – 236 kΩ	different when switch leads
R4	48 kΩ – 57 kΩ	different when switch leads
R5	363 Ω	?
R6	7.8 Ω	?
R7	10 kΩ
R8	10 kΩ
R9	10 kΩ
R10	1 kΩ	OK
R11	1 kΩ	OK
R12	1 kΩ	OK
R13	1 kΩ	OK