LCDInfo.com

Hi all,
I am repairing an old synthesiser ( Roland W-30 ), The original display was a SHARPS LM24014 2 (240x64) display. So I am trying to replace this with a DMF5005NF-SEW-BBE-CQ display, but to no avail, I have checked all the connections, and the pin assignments, they all seem to match up, and I cant find any short circuits or loose connections.... Can anyone point out the critical difference between these 2 displays which makes them incompatable??? Or is it just me being foolish and not being careful enough?

Here are some links to the PDF Data Sheets for reference.
DMF5005NF series
http://www.physics.brandeis.edu/undergr ... glcdap.pdf

SHARP LMF24014
http://www.aasi.net/development/datashe ... 24014h.pdf

I thank you all for your kind help in advance.
Bobo

Well assuming the Optrex is not defective;
- do they have the same backlight type? does the Optrex light up?
- can you adjust contrast? maybe it works but the contrast is different

_________________
My Plexeon-Insane LCD!-Or this one!-LCDinfo-LCDStudio

Hi, and thanks for the interest...
Yes the backlight lights up... and No... I do not get any graphics on screen at all, at any contrast level.

Is there any obvious reason what you can spot as to what might make these LCD screens not compatable? i.e. voltage? Pin configuration? etc. I'm worried I am missing something simple you see, and I am only beginning in the world of electronics.

Once again all the help given is gratefully received.

Well since the 2 have identical pin layout (you sure those are their exact datasheets?) i suspect bad wiring or a defective Optrex.

_________________
My Plexeon-Insane LCD!-Or this one!-LCDinfo-LCDStudio

Thank you, in that case I will create a new wiring loom for it, and take it from there.... With my innocence in electronics, the Voltages match up dont they... I am worried that one says that the LM24014 needs a negative voltage in VEE whereas the other requires Positive. could this cause a problem.

Looking at the datasheet sit looks like the Optrex needs max -23v on Vee and the SHARP takes -13v

Can you adjust contrast (not backlight) on the Optrex? It could be that the Vee is not enough for the Optrex to reach the right contrast; the display could be working but you can't see it.

_________________
My Plexeon-Insane LCD!-Or this one!-LCDinfo-LCDStudio

Hi, I think you may have something there... One piece of information I did not previously give is that I have sucessfully replaced the LCD unit before on a different keyboard ( Roland D-70 ) very similar... Anyway getting to the point... When I tried certain LCD types, the best I could get was a very faint display of the LCD graohics, and that was with contrast turned up full, suggesting that there was not enough voltage.

Before I fitted the current wiring loom to the display, I checked with a multimeter that all the connections were 'live' and that there were no short circuits, and triple checked the order of wiring too. So your observation of there possibly not having enough voltage getting through sounds right.

If the potentiometer was only delivering around 6.5v max, would there be a simple method to 'ramp' up the voltage from the pot. i.e. fitting some component between the POT and VEE?

Thanks for the help so far, I think progress is being made.

There's no way to 'boost' the negative voltage between pot and Vee i think.
The question is whether that onboard negative (DC-DC) controller can deliver more and is limited by the pot or that it is fixed at a max level.
In the first case changing to a smaller pot might help, in the second case you'll need to build your own DC converter that can supply the voltage you need; there's some simple circuits for that.
What i would also try is to measure the negative voltage level before the pot, then you know what it's max output-level is.

_________________
My Plexeon-Insane LCD!-Or this one!-LCDinfo-LCDStudio

Did this ever get resolved? I am trying to do the exact same replacement for a vintage chess computer. Based on other information on the net, www.dbit.com/~lansie/CUJ/Hardware.htm maybe the issue was the fact that the two boards number the pads as mirror image??

Turns out that for my application a Solomon Godentek LM6270SYL is totally compatible. The voltage range for contrast has enough overlap to just work at the extreme end of the contrast rotator control.

By the way, the info you can find on the net that the LM24014 and the Oprex 5005N have reversed pin outs seems to be wrong! Optrex worked with my original cable (but only a faint image due to small overlap of contrast voltage ranges).