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Author Topic: PCEGT replace with 3.5inch TFT LCD  (Read 6740 times)

thesteve

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #270 on: October 29, 2015, 03:35:44 PM »
no CCW
read at the 22uf 35V cap
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Keith Courage

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #271 on: October 29, 2015, 04:02:39 PM »
Quote from: wilykat on October 29, 2015, 10:33:12 AM
Can you try tapping off the middle pin of the power switch? That is 8-9v unregulated power from either DC in jack or batteries.  (middle pin is because NEC wired the switch a bit strange. When viewing the PCB with the switch solder spot up, left and middle are connected when the switch is "OFF" and middle and right is connected with switch is "ON", the right pin goes to the regulator circuit and middle is unregulated input.

If it still doesn't work, you got unlucky :( All the LCD I've tried always worked from either regulated 5v or from unregulated 8-9v

I've always just tapped the middle pin of the on/off switch for power as well. Never had any issues.
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famiac

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #272 on: October 30, 2015, 04:14:58 PM »
Got it working! Thanks for the help, steve.

It would't work from unregulated power. I connected 5V,  ground, VGL, and VHL as shown in the thread steve referred me to
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thesteve

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #273 on: October 30, 2015, 04:58:08 PM »
That was my thread on the other forum,  from when I did that board
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famiac

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #274 on: October 31, 2015, 06:27:53 AM »
Yeah i noticed. Thanks
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Keith Courage

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #275 on: November 15, 2015, 11:10:37 PM »
Got 3 new screens in the mail over the weekend. They work just fine but what's weird is that if you turn the brightness past 60 everything gets super bright out of nowhere. Meaning the brightness will go up gradually as it should from 0-60 and then bam super bright. Almost like someone turned the brightness up all the way. No change whatsoever from 60-100. Just as bright as possible from 60-100

Anyone ever come across any screens like that before? Any fix for it or is it just a bad design to where I should return them?

In all honesty 50 for the brightness seems good enough so I may decide to keep them. Just thought it was odd that when I tested them I couldn't go past 60 on the brightness level without being blinded.
« Last Edit: November 15, 2015, 11:18:49 PM by Keith Courage »
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Vimtoman

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #276 on: November 16, 2015, 12:39:38 AM »
You could try a resistor across the inner and outer pin of the pot
To change it from LOG to LIN or visa versa.
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Keith Courage

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #277 on: November 16, 2015, 12:50:29 PM »
There are no potentiometers. Just push buttons that control the brightness, contrast, tint etc.....
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Vimtoman

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #278 on: November 16, 2015, 06:11:52 PM »
Bummer.

You could try attenuating the composite video slightly using a half bridge resistor circuit.

Use a 100R multi turn pot and a fixed value of say 50R in series so it does not go any lower.

May work.

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thesteve

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Re: PCEGT replace with 3.5inch TFT LCD
« Reply #279 on: November 17, 2015, 03:31:57 PM »
the issue is in the software
you could return them or not have the buttons showing
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