Brightness control on Xenarc 700TSV

**coastaldamage** · 06-24-2009, 06:45 PM

Has anyone found out how to control the 700TSV's brightness with the car? I was thinking about tying into my car dimmer switch.

**kuo** · 06-24-2009, 06:55 PM

did just that a few weeks ago. see this thread. This is the thread that got me started. your wire colors may vary. mine was orange.

**coastaldamage** · 06-24-2009, 09:27 PM

Have you managed to get all the bugs worked out?

**kuo** · 06-25-2009, 10:42 AM

yes i used bigger resistors and added a few smoothing caps and the interference is gone. very happy with the results now.

**coastaldamage** · 06-25-2009, 03:33 PM

Can you show me what you used and how to hook it up?

**kuo** · 06-30-2009, 08:25 AM

i would first measure the output of your dimmer knob. more than likely it goes from 0V to 12V. If this is this is the case you can make a voltage divider as shown in the post i linked above. the lcd controller board sends from 0 to around 3 or 4V down the backlight control wire depending on what the backlight level is set to. you basically cut that wire the end going into the inverter to your car's dimmer knob. i used a 20k and 10k ohm resistor with a diode in front to make my voltage divider. i also added a few small ceramic capacitors. my interference issues went away after increasing the size of the resistors but the caps may be helping too.

**joshuo** · 06-30-2009, 08:35 AM

Could you just put a variable resistor in line with the backlight?

**kuo** · 06-30-2009, 09:10 AM

most cars use a variable resistor (rheostat) for the dimmer knob, but i think the point here is to tie the screen brightness to the brightness of the dash lights. this way, when you turn your headlights on, your screen's backlight dims along with your dash lights. imho having a separate dimmer knob for the screen is only marginally better than using the osd to dim the backlight.

**joshuo** · 06-30-2009, 10:28 AM

good point.

Alternatively, is there a way to have the up and down arrow buttons change the brightness instead of volume on the 700TSV?

**coastaldamage** · 09-24-2009, 03:57 AM

What I thought about doing, but have not had a chance to test it yet, was to use another variable resistor(potentiomitor parden my poor spelling) and setting it to where the output ranges from 0-3.4 in direct relation to 0-12. This would allow me to use it on a different screen, or possible something totally different.