NorthernLightX Posted February 8, 2004 Report Share Posted February 8, 2004 Hi, I have a Crystalfontz LCD (CFAH2004A-YMC-JP) with backlight, only the backlight does not go on.I've got a PIC with only the bootstraploader on it. Today my neighbor and I checked all the wiring, and all boards connected at the moment, for shorts and other problems and found none.What I do see when the power is plugged in is blocks on row 1 and 3 (it's a 20x4 LCD). I can play with the brightness of the blocks by tweaking the pot, but the other pot does absolutley nothing for the backlight. We also measured the response from both pots, and they're both working.In the techsheet for the LCD it says that the max voltage for the backlight is 4,8, and the typical voltage for the BL is 4,5. I measure 5,12 - what can I do to get this within specs, or is it more probable that the BL is dead already? Quote Link to comment Share on other sites More sharing options...
Synergic Posted February 8, 2004 Report Share Posted February 8, 2004 heya!"What I do see when the power is plugged in is blocks on row 1 and 3 (it's a 20x4 LCD)"That´s ok!  ;)"In the techsheet for the LCD it says that the max voltage for the backlight is 4,8, and the typical voltage for the BL is 4,5. I measure 5,12 "It must be ok.Is a little diference.Are you sure that the + and-  conections of BL are ok?Maybe are reversed?Or maybe that can help http://www.midibox.org/cgi-bin/yabb/YaBB.cgi?board=troubleshooting;action=display;num=1061099622 Quote Link to comment Share on other sites More sharing options...
NorthernLightX Posted February 8, 2004 Author Report Share Posted February 8, 2004 heya!"What I do see when the power is plugged in is blocks on row 1 and 3 (it's a 20x4 LCD)"That´s ok!  ;)"In the techsheet for the LCD it says that the max voltage for the backlight is 4,8, and the typical voltage for the BL is 4,5. I measure 5,12 "It must be ok.Is a little diference.Are you sure that the + and-  conections of BL are ok?Maybe are reversed?Or maybe that can help http://www.midibox.org/cgi-bin/yabb/YaBB.cgi?board=troubleshooting;action=display;num=1061099622Hi,I sort of knew that the logic was still ok, cause the lines showed up (already read that on the Crystalfontz forum). Am reading all posts over there now to see if similar problems are described.I am using a Core_V2 board, with 10k pot and all other components that are in the design.I will make an extra check on the - and + of the backlight, but am 99% sure that i did it correctly... Will post followup this afternoon.Thanks for the tips! Quote Link to comment Share on other sites More sharing options...
NorthernLightX Posted February 8, 2004 Author Report Share Posted February 8, 2004 Well what do you know, the + and - where actually reversed! (so there's that 1% uncertainty ;D ) Going to fix this right away.(setback is that by dragging everything upstairs my powerlead just broke... need to fix that too)Thanks!P.S.just to be on the safe side: is there a way to lower the voltage from 5,12 to 4,8v for the backlight? I really don't want to blow it... Quote Link to comment Share on other sites More sharing options...
Steven_C Posted February 8, 2004 Report Share Posted February 8, 2004 you could try another voltage regulator, as the voltage tends to vary between different specimens. Or you could put a series resistor in the path to the +5v supply pin on the Backlight. I think I used about 200ohms on my old midibox 64. (not in the mood for pulling apart right now!)Arrgh! it is just next to me so I pulled it apart anyway! I actually had a 10k pot in series with the LED backlight... (not a suitable value, or current rating actually! Better to use a 1kohm, set to a setting that gives good brightness, take it out, measure the resistance, and then substitute a fixed value 1/2 watt resistor in its place ;) depending on what the current rating of your backlight is. (power = volts x current)glad you got it working! Quote Link to comment Share on other sites More sharing options...
Synergic Posted February 8, 2004 Report Share Posted February 8, 2004 heya!!Good!! Nice work!! Quote Link to comment Share on other sites More sharing options...
NorthernLightX Posted February 9, 2004 Author Report Share Posted February 9, 2004 Everything works fine now. the voltage is still a bit high, perhaps i will solder a resistor in between.Just connected the first SID too, now flash the pic and then... noiZe! Quote Link to comment Share on other sites More sharing options...
Twin-X Posted February 10, 2004 Report Share Posted February 10, 2004 heya!"What I do see when the power is plugged in is blocks on row 1 and 3 (it's a 20x4 LCD)"That´s ok!  ;)I have the core powered up and the lcd attached. Bootstrap 1,1 loaded. I see block 1 to 20 on row 1 lit.So this is not good? (i have a 2x20If i have something wrong what can i do to fix it? Quote Link to comment Share on other sites More sharing options...
NorthernLightX Posted February 10, 2004 Author Report Share Posted February 10, 2004 Hi Jef,that is upposed to be happening, it's the LCD's way of telling "hello, i'm alive, please send me some info to display...".You should also chek my topic in Testing/Troubleshooting, as you're probably facing the same prolem flashingyour PIC's, Thorsten's idea is that I've used an older version of the bootstraploader, namely 1.1 instead of 1.1b. Since you burned those for me I assume you're using th same version. Could you confirm that?Cheers,NLX Quote Link to comment Share on other sites More sharing options...
Twin-X Posted February 10, 2004 Report Share Posted February 10, 2004 1.1b is loaded Quote Link to comment Share on other sites More sharing options...
NorthernLightX Posted February 11, 2004 Author Report Share Posted February 11, 2004 My box is working, if anybody is interested! Quote Link to comment Share on other sites More sharing options...
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