Help Gareth Magennis, Quadraverb LCD?
stoneattic
I found an old usenet post in which you had figured out how to replace
an Alesis Quadraverb LCD with a standard off the shelf model LCD.
Could you expand on this? My backight has died, which is a real pain
at gigs since it's usauly in the dark.
Thanks!
Preben Friis
<l...@stoneattic.com> wrote in message
news:1159874101.5...@e3g2000cwe.googlegroups.com...
I'm not Gareth, but the backlight in my BRC went dark once. It is the same
display type as the Quadraverb.
I bought a cheap replacement display, but later found out that the
connections were different, so I disassembled both and swapped the LED
backlight element instead. Pretty simple operation. Now I have a BRC with a
green backlight instead of the orginal amber.
There are companies on the internet that specialises in replacement
backlights, but for that size display, it will probably be cheaper to just
by a complete display and do the swap.
/Preben Friis
Gareth Magennis
>
> I found an old usenet post in which you had figured out how to replace
> an Alesis Quadraverb LCD with a standard off the shelf model LCD.
> Could you expand on this? My backight has died, which is a real pain
> at gigs since it's usauly in the dark.
>
>
part number 214-3525 Powertip PC1602LRS-H
the above part is the one that works. There are lots of different versions
of this, the above is the only one I found that has the 16-pin header
arrangement. You will have to do a few things to make this happen:
First you will have to remove the header pins from the old LCD and solder
them onto the new one, ALL EXCEPT pin 3. Then you will need to cut cables 1
and 2 of the ribbon cable and reverse them. This is because the Alesis LCD
uses pin 1 as VCC (+5 volts) and pin 2 as ground, whereas the Powertip
device has these the other way round - pin 1 is ground and pin 2 is 5 volts.
If you connect the Powertip device without reversing these 2 connections it
will be destroyed immediately.
Pin 3 is the contrast voltage. The Alesis sends a negative voltage to this
pin, the Powertip wants a positive voltage, which is why you must not
connect pin 3 of the header. Leaving it floating means the LCD will work OK
but it is a bit dark. You can improve this by fitting a diode between pin 3
and ground. Connect the anode to pin 3 and the cathode to ground - this
gives about 0.6 volts on pin 3 which is about ideal. If you connect the
diode round the wrong way the display will not work, but won't be damaged.
To get the backlight to work you will need to connect pins 15 and 16 to pins
2 and 1. Make sure you don't get these the wrong way round or you may short
out the power supply. You will find that one of these can be connected by
soldering accross 2 pads on the back of the pcb. The other will have to be
conected by a wire. You can download the datasheet from RS which will help,
or go to the Powertip website.
You will now have to glue the LCD in place as the screw holes do not match
up. Silicon sealant or hot melt glue is your best bet.
If you are not good or experienced at soldering small pcb's I would advise
you to find someone who is to do this, this requires a certain amount of
skill to achieve.
Good luck,
Gareth.
----- Original Message -----
From: Thomas
To: sound....@btconnect.com
Sent: Saturday, August 20, 2005 2:59 PM
Subject: Quadraverb Display
Hi,
i read an information that you managed to replace the quadraverb display
with an off-the shelf display.
You offered more information regarding this.
This is definitely interesting for me, since my display is broken.
Can you help ?
Regards,
Thomas
Gareth Magennis
"Preben Friis" <no...@technologist.com> wrote in message
news:4522aa69$0$177$157c...@dreader1.cybercity.dk...
The Quadraverb backlight can't be swapped out, unfortunately, as they use
integral LED's. Yes, for other displays that use EL sheet and an inverter,
you can buy from specialised companies or buy kits of sheets of backlight
material and special connectors and conductive glue pads to attatch them,
and make your own - I have done this a lot. You also have a choice of funky
bright colours!
In the UK, the quadraverb spares dealers charge far too much for a
replacement display making the repair pretty much uneconomic (buy a used
reverb from Ebay instead and use your old one blind).
Gareth.
stoneattic
post my results.
Preben Friis
"Gareth Magennis" <sound....@btconnect.com> wrote in message
news:GKidnZB-Os2...@bt.com...
> The Quadraverb backlight can't be swapped out, unfortunately, as they use
> integral LED's.
But the BRC display is the same type as the Quadraverb and I managed to swap
the LED backlight?
No inverter, no EL...!?
/Preben Friis
Gareth Magennis
You may well be right actually, nearly all the Quadraverb displays I have
changed have been because the display itself has been faulty - they show
hyroglyphics or fade to nothing.
The part I mention for replacement is actually a reasonably cheap display.
Since I know the Quadraverb displays have poor reliability ( I haven't come
across any other piece of equipment that has such consistent display
failures) it would seem better to change the entire unit if you have just
gone and bought one just for the backlight.
There is also significant risk of damaging displays by removing the
backlight or having to take it apart to remove the backlight in the hope it
fits your old display- it is not always possible to get all the pixels
working again, and this is something I consider very risky, and then you
have 2 useless displays on your hands. Been there, done that.
Gareth.