problem in DT-9205A multimeter

[Mohamed Gamal Mazen]

Hi guys i have this multimeter. its problem after replacing the battery all measuring choices gives -1 with the low battery indication sign and i have tried another battery but its doing the same thing. so if the schematic i have seen on the internet for this multimeter was right this means that icl7106 is damaged or there is another problem ? please help

 

[caps]

There may be short circuits in the multimeter circuit. Pay attention to the 74HC14D chip.

 

[caps]

If there is another multimeter,check the new battery.

 

[Mohamed Gamal Mazen]

I have checked it its working ,i'm going to check the schmitt inverter

 

[caps]

At the same time, check the quality of the contacts of the display cable and the voltage between the com of the multimeter and the + battery. There should be about 3V.

 

[Mohamed Gamal Mazen]

i have checked the voltage between the com of multimeter and the + battery when the switch is closed is about 0.74 V and when it's opened the voltage is 7.68 V what i have to check now ?

 

[Mohamed Gamal Mazen]

after some check i found Q4 and Q5 transistors j3 (s9013) are shorted in emitter and collector is this a reason for this problem ?

 

[caps]

i have checked the voltage between the com of multimeter and the + battery when the switch is closed is about 0.74 V and when it's opened the voltage is 7.68 V what i have to check now ?

This is checked at the 20mA switch position.
The power of the multimeter is turned off. At the switch position of 200 mV, the input resistance between the com and v terminals should be 1 MΩ.

 

[Mohamed Gamal Mazen]

This is checked at the 20mA switch position.
The power of the multimeter is turned off. At the switch position of 200 mV, the input resistance between the com and v terminals should be 1 MΩ.

yes it's 1 MΩ but forgive me i still don't understand what to do ?

 

[caps]

and when it's opened the voltage is 7.68

What is the switch position?

 

[Mohamed Gamal Mazen]

What is the switch position?

every position

 

[caps]

after some check i found Q4 and Q5 transistors j3 (s9013) are shorted in emitter and collector is this a reason for this problem ?

About transistors.How can they have a short circuit if you just replaced the battery.
To answer your question, it is better to look at the diagram.
Either you take a photo of your board, or look for a diagram of your version of the multimeter.

 

[caps]

every position

Then it is not very good.