SammichFM Kit LCD Backlight

[toneburst]

Apologies if this has been covered before, but I recently bought a SammichFM kit from Wilba, with the (really nice) neg. green LCD display. I decided to try to put together the base PCB without the jumper to supply a larger voltage to the LCD backlight. The display looks OK, but is quite dim. Should I add this jumper at JR4A? I'm reluctant to try it without confirmation that it won't fry the display.

Cheers,

a|x

[Flemming]

The LCD is still dim after you adjust the two trimpots?

[toneburst]

Hi Flemming,

it's not very dim- just not as bright as I'd been expecting. I did adjust both trimpots for brightness and clarity of the characters.

a|x

[jbdiver]

I think I had the opposite experience. I've tried it with the jumper in and out. I didn't damage the LCD either way. I think the jumper is out now. The LCD looks acceptable to me.

[wavecircle]

My backlight is very dim too. I adjust with the trim pots and it just gets fainter until it disappears.

[Wilba]

All the LCDs I sell now are high-power LCDs and require a shunt in JR4... otherwise the LCD only gets low current (max. 25mA) which is only good for edge-lit LCDs like some white-on-blue LCDs or the amber/true green ones I was selling in the first few batches (before I switched to standard yellow-green LCDs).

[toneburst]

Thanks for the info Wilba. I've installed the jumper, and my LCD is now nice and bright.

Cheers,

a|x

[Wilba]

I forgot to add, to keep the current reasonable (100mA) and prolong the life of the LCD, set the brightness pot to half-way or less.