The VEE level should be fine about 4.65V. As long as it does not change when 
you see the screen DIM. Since the LCD is fine in another computer that saves 
checking things on it.

 

You can try checking the voltage at pin 4 of the LCD connector. This is the 
contrast setting voltage after it does through a transistor.

 

Jeff Birt

 

From: M100 <[email protected]> On Behalf Of ExPLIT | Pawel 
Radomychelski
Sent: Wednesday, May 5, 2021 5:00 PM
To: [email protected]
Subject: Re: [M100] NEC PC-8201(A) Recapping Help

 

Did again some measuring:

 

Pin          Function                                                           
                                                  Measured           

3              VEE (-5V)                                                        
                                   -4,65V
4              VB   (Battery charge voltage)     +4,98V

5              GND                                                              
                                                      
6              VDD (+5V)                                                        
                                 +5,00V

 

Can -4,65V instead -5V bea a Problem, Jeff ?

 

 

 

-- 

Kind regards / 

Mit freundlichen Grüßen

 

ExPLIT IT Solutions

Pawel Radomychelski

 

 

 

-----Original Message-----

From: ExPLIT | Pawel Radomychelski <[email protected] 
<mailto:explit%20%7c%20pawel%20radomychelski%20%[email protected]%3e> >

Reply-To: [email protected] <mailto:[email protected]> 

To: [email protected] <mailto:[email protected]> 

Subject: Re: [M100] NEC PC-8201(A) Recapping Help

Date: Wed, 05 May 2021 23:45:06 +0200

 

Thanks guys.

LCD unit is working fine on another NEC.

 

So maybe some chips.

Need to find a guru (who doesnt fear the word osciloscope) 🙂 here in Europe....

 

 

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