[sdiy] Why do LCDs die?

Kenny Balys kenny at beatkamp.com
Mon Dec 31 05:29:38 CET 2018

I have (possibly) the first Timex LCD wrist watch and its
display has gradually faded over time and is now unreadable.

My guess is that the liquid has dried out / been lost and this
renders the display non functional.

Would love to hear more opinions on this. The LCD in my Emax
appeared to do the same thing. I put in a new red on black OLED
and that just looks fantastic now.

The only Z80 person I know of in the synth world is Tauntek.

On 31.12.18 04:17 , MTG wrote:
> To the OP, probably all of the above as being reasons for failure.
> A lot of the Z80 machines really push the timing to memory map those LCDs. I
> don't know what it is exactly since I've never really studied the Z80. There is
> one guy doing a bunch of Z80 upgrade work these days, but I can't recall who.
> Anyway the MRC .. U118 is a 74HCTLS on the ones I fixed. I had to replace it
> with a 74LS00. Then it was fine. Don't ask me how I came to that conclusion but
> maybe with a schematic in front of me I could say better.
> The Yamaha TX7 is another odd beast to fix and it's not even a Z80 (it's a 6303
> which is a 6801 more or less).
> Not sure I would pop an OLED or VFD in these two machines as they are finicky
> enough with LCDs.
> On 12/30/2018 7:34 PM, Tony K wrote:
>> Hi Tim, I can't answer your question as to why lcds die, as you put it, but I
>> have several older units that are getting harder to read, such as the Lexicon
>> MRC, and Korg Wavestation A/D rack( now sold partly for aformentioned display
>> issues) . I have a contrast control on the former unit but at some point ai
>> will have to switch to a modern OLED? , or VFD ( Noritake , old school
>> solution) .
>> I think MTG has something about it on his site , at least the MRC.  I have
>> been putting this off. Come to think of it the Novation X-Station contrast is
>> getting weaker as time goes on, but that one is meant to be on all yhe time -
>> I use it as my audio interface. So it's a safe bet to say these displays do
>> have a MTBF. The old Hitachi 16x2 is not a problem to get lcd replacements (
>> ie MMT-8 etc.) I know Noritake VFDa make drop in replacements for those, or
>> used to anyway. But then there is the high voltage filament voltage to worry
>> about and the fragility.
>> Anyway I love those VFD's on the Xpander.
>> Tony K
>>> On Dec 30, 2018, at 9:53 PM, Tim Parkhurst <tim.parkhurst at gmail.com> wrote:
>>> So, I have an old Roland U-220 that I haven't used in a few years, but I keep
>>> it around because I do love the piano and string samples. The fretless bass
>>> and the drums are pretty good too. Also, I'd be lucky to get $50 for it these
>>> days. Long story short, I turned it on the other day and the LCD was barely
>>> visible, getting dimmer to the point after a few hours where it is completely
>>> unreadable. The backlight is okay, but the digits themselves can't be seen. I
>>> see there are replacements on the market, so I should be able to resurrect
>>> it, but this begs my original point:
>>> What causes LCDs to die in the first place? Are the crystals themselves
>>> unstable? Is it the high-frequency excitation required that causes an
>>> eventual breakdown? Or is it mechanical, with small connections or wire bonds
>>> breaking down with time? Do we replace them because they are unrepairable, or
>>> is it simply a matter of replacement being quicker and cheaper than repair?
>>> Is there an internal adjustment to crank up the contrast on this old beast
>>> (can't change the contrast from the front panel settings since I can't see
>>> the display to navigate)?
>>> Awaiting the collective enlightenment from the SDIY hive mind...
>>> Tim (do Borgs get hive mind hives?) Servo

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