Problem identifying smd component/problem

[steadyhands]

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.

 

[narkeleptk]

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.

 

[ronsimpson]

Gas Discharge Tube. Used to short overvoltage and lightning.

 

[steadyhands]

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 )