Analogue-sequencer

Hello list..  my pled display has gone blank recently.  All connections 
internally look/feel solid.  Where can I probe to check for voltages to 
see if the display is truly dead?

Crystalfontz no longer carries these, of course I still want to use 
PLED (they look so cool) anyone know where I can get one (RED!???)

thanks for any tips.

~Steve

> Hello list..  my pled display has gone blank recently.  All 
> connections 
> internally look/feel solid.  Where can I probe to check for 
> voltages to 
> see if the display is truly dead?

If your P3 is booting up, then the PLED module itself is communicating as
expected with the CPU, so it could be the display element or the drive
circuit for it that has failed.
First thing to check is that the voltage from the brightness trimmer is
reaching pin 3 on the module.
If that connection is broken, it will be blank. Doesn't seem too likely
though.

Although they look great, the reliability of the PLED modules hasn't been
anywhere near as good as it should have been.
Premature dimming of pixels has been more of a problem than outright
failure, but I think 2 or 3 modules have died now, out of around 200.

For modules that fail under warranty, I'm offering white on blue LCD modules
as a replacement.
It may be that the PLED modules that have had problems wre from a bad batch,
but I'm not taking a chance on them again.

Best regards,
Colin Fraser
Sequentix Music Systems Ltd
http://www.sequentix.com

Well, I dug in today to try and figure out my display issue.  Ive 
got V+ around 4.9v at pin 2 and the display brightness V+ is there at 
pin 3 which varies with the trim pot.

  The P3 does boot up, and I can run it (tribute to Colin when 
something as complex as this is also simple enough to run without a 
display:)

  Anyway, is there anything else I could check?  Perhaps a pin or 
something that should be high when the display is active?  The cable 
and connector is good, I checked the header to the display for 
continuity and all 14 wires checked out OK.  It may be the driver IC?

  By the way Colin, I built this from a kit, but its been running 
fine for a year up until this.

  Anyone in the US know where to get an 88x44mm LCD in blue or red or 
something exciting?  

thanks for any thoughts. . .
~Steve
everyone, turn that PLED display brightness DOWN!!



--- In analogue-sequencer@yahoogroups.com, "Colin Fraser" <colin@...> 
wrote:
>
> 
> > Hello list..  my pled display has gone blank recently.  All 
> > connections 
> > internally look/feel solid.  Where can I probe to check for 
> > voltages to 
> > see if the display is truly dead?
> 
> If your P3 is booting up, then the PLED module itself is 
communicating as
> expected with the CPU, so it could be the display element or the 
drive
> circuit for it that has failed.
> First thing to check is that the voltage from the brightness 
trimmer is
> reaching pin 3 on the module.
> If that connection is broken, it will be blank. Doesn't seem too 
likely
> though.
> 
> Although they look great, the reliability of the PLED modules 
hasn't been
> anywhere near as good as it should have been.
> Premature dimming of pixels has been more of a problem than outright
> failure, but I think 2 or 3 modules have died now, out of around 
200.
> 
> For modules that fail under warranty, I'm offering white on blue 
LCD modules
> as a replacement.
> It may be that the PLED modules that have had problems wre from a 
bad batch,

> but I'm not taking a chance on them again.
> 
> Best regards,
> Colin Fraser
> Sequentix Music Systems Ltd
> http://www.sequentix.com
>

>   Well, I dug in today to try and figure out my display issue.  Ive 
> got V+ around 4.9v at pin 2 and the display brightness V+ is there at 
> pin 3 which varies with the trim pot.
> 
>   The P3 does boot up, and I can run it (tribute to Colin when 
> something as complex as this is also simple enough to run without a 
> display:)
> 
>   Anyway, is there anything else I could check?

I'm pretty sure you've got a dead module.
I'd say it was the driver circuitry rather than the PLED matrix itself.
Excessive brightness causes a more rapid reduction of the PLED pixel output,
but I don't think it would be to blame for the failure in this case as teh
fading affects each pixel depending on how long it has been switched on for.

>   Anyone in the US know where to get an 88x44mm LCD in blue or red or 
> something exciting?  

The white on blue modules I've got now look like this -
http://www.sequentix.com/images/p3-lcd-blue.jpg
They do look nice, though still not as nice as PLED, and without the
instantaneous response time.

The makers page is here...
http://www.lcd-module.de/eng/doma/doma.htm

Unfortunately they don't list a US supplier, but the outline of the module
is a standard type, so you should be able to find something similar.
LCD modules are quite a bit thicker than the PLED module, so you need longer
mounting screws and spacers to fit the mounting posts in a production case.
Earlier PCB sets may also need a little bit of width shaved off the function
key board.

Best regards,
Colin Fraser
Sequentix Music Systems Ltd
http://www.sequentix.com