Problem identifying smd component/problem

Hello Folks,

new poster here, just a hobbyist, looking to refine my craft and love for electronicics repair.



below I have a metering device, made by Bluelabs - Dosetronic with attached leads it reads pH/TDS,water quality etc and displays on a sub-screen connected to ribbon cable.

when power turned on only 1 led turns on, tried replacing Led with no such luck, moved on to replace both 2 sip 5v to 5v 200mA convertors as I found output to unit close to my circle not output 5v. but I’m having issues identifying this chip it is labeled naog ? It gets real HoT like 50plus degrees, so I suspect that’s my next component to trace out.



there are no available diagrams, at least available to public for this device.


thanks for any input.

U10 could be https://www.mouser.com/datasheet/2/268/21335b-29125.pdf but I didn't take much time in seeing if it makes sense in your circuit, so be sure to do that.
GD1 is a gas diode. I don't know the value sorry but maybe you can look it up with the id printed on it.

Gas Discharge Tube. Used to short overvoltage and lightning.

Hello, and Thankyou Narkeleptk, Ronsimson,
Today I have learned much, so I ordered a couple of those GDTs, and also checked voltages coming from input on VDD/voltage out/bypass. On Narkeleptks insight:

unsure of how to check what the voltage needs to be, tracing output to next known ic?

could this also be a driver issue, it runs 6 individual 7segment display looking for equivalent non obsolete package driver QSOP-24 ( as1116e )