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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
Posted to sci.electronics.repair,sci.electronics.design
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Dead pixels or...?
LCD display having issues:
http://tinyurl.com/jovnnra Dead pixels, corroded/dirty ribbon cable contacts, or something else? |
#2
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Dead pixels or...?
On Saturday, April 2, 2016 at 12:03:51 PM UTC-7, bitrex wrote:
LCD display having issues: http://tinyurl.com/jovnnra Dead pixels, corroded/dirty ribbon cable contacts, or something else? Doesn't look like dead pixels, more likely a logic corruption. The wrong letter, maybe just a weak bit in whatever holds the program memory. Start looking at the power supply (hey, it's a WEAK bit, could just be low battery). |
#3
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Dead pixels or...?
On Sat, 2 Apr 2016 14:47:35 -0700 (PDT), whit3rd
wrote: On Saturday, April 2, 2016 at 12:03:51 PM UTC-7, bitrex wrote: LCD display having issues: http://tinyurl.com/jovnnra Dead pixels, corroded/dirty ribbon cable contacts, or something else? Doesn't look like dead pixels, more likely a logic corruption. The wrong letter, maybe just a weak bit in whatever holds the program memory. Start looking at the power supply (hey, it's a WEAK bit, could just be low battery). I agree. Check the power supply voltage. My guess(tm) is that the display has a COB (chip on board) that has a broken wire bond and the display needs to be replaced. Just touching the blob of epoxy is sometimes enough to trash a wirebond and missing pixels cannot be produced by data errors between the synth and the display. 1601 displays are quite common and cheap, but not with EL backlighting. If you're going to replace it with an LED backlighting version, you'll need to: 1. Check the thickness of the display as they do vary and may not fit. 2. Disarm, disconnected, and possibly remove the EL high voltage power supply. 3. Find a way to power the backlighting. Some run on 5.0V, some bring out just the diodes and need a series resistor, and I ended up with one that wants 4.4VDC. I thought it was easy, but it took me several evenings to replace the display: http://802.11junk.com/jeffl/Korg_DSS-1/ -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#4
Posted to sci.electronics.repair,sci.electronics.design
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Dead pixels or...?
bitrex wrote:
LCD display having issues: http://tinyurl.com/jovnnra Dead pixels, corroded/dirty ribbon cable contacts, or something else? Yes, that looks like a ribbon-zebra-LCD contact problem. Carefully dismantling the assembly, cleaning the LCD and ribbon contacts and then getting it back together is risky, but then it isn't working now, so not that much to lose. Jon |
#5
Posted to sci.electronics.repair,sci.electronics.design
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Dead pixels or...?
Jon Elson Wrote in message:
bitrex wrote: LCD display having issues: http://tinyurl.com/jovnnra Dead pixels, corroded/dirty ribbon cable contacts, or something else? Yes, that looks like a ribbon-zebra-LCD contact problem. Carefully dismantling the assembly, cleaning the LCD and ribbon contacts and then getting it back together is risky, but then it isn't working now, so not that much to lose. Jon Thanks for the reply. The original LCD was very old, and it literally crumbled in my hands as I attempted to disassemble it from the board to clean the contacts. Fortunately, I managed to find a lot of 3 unlit LCD displays on eBay that look like drop in replacements for the original - they use the same SMT OEM Hitachi display controller in a similar package, and even the PCB layout is very similar. The date code on the original board looks like 1986, these are from the early 1990s. $3 plus shipping for the lot. Seems like a much easier solution... -- ----Android NewsGroup Reader---- http://usenet.sinaapp.com/ |
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