PR23 malfunction

[WSTOK]

Hi, I have installed all components on the board and checked all components are installed correctly according the manual for PR23. Then, I follow the instruction from the UIC00B manual to load the sample program to the PR23 robot and it show successful. When I turn on the robot the LED is on, the beep sound can be heard and the IR sensor is function ok but the LCD was blank at all.

Pls. refer to details below:
- Checked PIC (VCC 5v) – ok
- Checked 5V output from 7805 - ok
- Checked gnd pad on LCD to LM7805 body connectivity – ok.
- Checked LCD Vcc pin had 5v supply.
- Checked Pin RB5 no 5V voltage.
- Microcontroller (can write and read hex but not functioning).
- Press the reset button beep sound can heard.
- Press the SW1 and SW2 one time accordingly ,the robot move straight forward only.

Pls. advise the solution thanks!

[robosang]

Woh... you get yourself a PR23, is a good DIY set. I don have one, but one of my friend get it last year, work perfectly.

Seem like your LCD is having problem

[hyng]

Hi, I have installed all components on the board and checked all components are installed correctly according the manual for PR23. Then, I follow the instruction from the UIC00B manual to load the sample program to the PR23 robot and it show successful. When I turn on the robot the LED is on, the beep sound can be heard and the IR sensor is function ok but the LCD was blank at all.

Pls. refer to details below:
- Checked PIC (VCC 5v) – ok
- Checked 5V output from 7805 - ok
- Checked gnd pad on LCD to LM7805 body connectivity – ok.
- Checked LCD Vcc pin had 5v supply.
- Checked Pin RB5 no 5V voltage.
- Microcontroller (can write and read hex but not functioning).
- Press the reset button beep sound can heard.
- Press the SW1 and SW2 one time accordingly ,the robot move straight forward only.

Pls. advise the solution thanks!

Nice troubleshooting skill..
Is the LCD totally doesn't show anything or is there any black row showing?
Maybe you can attached a photo of the LCD when the PR23 is ON.
Can you check for one more thing, is the Vee pin on LCD really connected to contrast preset?

Hope to hear from you soon.

[WSTOK]

Hi hyng & robosong,

When turn on my PR3 the LCD totally doesn't show anything (The LED from LCD was off) and 0v supply from pin RB5 to Q2 (2n2222) base, so the LCD (LED-) notable to drain the 5v to the gnd and the Vee connectivity to contrast preset is ok. By the way, when PR23 turn on , is it the LCD also will follow turn on and showing something ?thanks and hope to hear from you soon.

[redips_id]

I think, this is the meaning of "black row showing" by hyng.

LCD.jpg (137.92 KiB) Viewed 5770 times

NORMALLY, if this "black row showing" exist, it shows that the LCD in a good condition.
I hope this will helpful.
Thank You.

[sich]

Did u try to turn the preset to adjust the contrast?

[WSTOK]

Hi, pls. refer to the attached file and pls. help me...thanks

[mec]

hi,

The voltage regulator input is only 5.2V? That's weird for me. I not sure the input voltage for this robot but i do know that 7805 input should higher then that in order to produce 5V. 3.81V output is too low for me. BTW, what battery you use? Anyway, this is just my two cent

[hyng]

Hi, pls. refer to the attached file and pls. help me...thanks

I have just tried to supply input voltage less than 6V to PR23, and the result is quite similar to yours. The buzzer will be ON for a while when the robot is switched ON which is normal but the LCD show nothing. So i am assuming that the root cause is from the input voltage if referring to the photo you have attached.
The input voltage must be at least 7V for the regulator to generate 5V but remember that motor power should not more than 6V. I guess you need to try increasing the input voltage.

[robosang]

I thought initially the voltage is 5V for the PIC's VCC? Maybe the battery drain out? Should have use adapter to test.