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
The LCD is still dim after you adjust the two trimpots?
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
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.
My backlight is very dim too. I adjust with the trim pots and it just gets fainter until it disappears.
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).
Thanks for the info Wilba. I’ve installed the jumper, and my LCD is now nice and bright.
Cheers,
a|x
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.