New LCD but apparently with its own baggage

[napierzaza]

I recently bought a replacement LCD for my MIDIBOX SID. It's off of ebay and it's an electroluminescent backlighted display. I got a maxim icl7660 and wired it up as per the schematic, but I have no idea how to integrate it into the core module using the existing pot /transistor.

Also I'm not even getting any non-lit characters for the display. Do I need any special wiring elsewhere or something? It's apparently hitachi compatible.

Item i bought:

http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=160249490629&ru=http%3A%2F%2Fsearch.ebay.ca%3A80%2Fsearch%2Fsearch.dll%3Ffrom%3DR40%26_trksid%3Dm37%26satitle%3D160249490629%26category0%3D%26fvi%3D1

icl7660:

http://datasheets.maxim-ic.com/en/ds/ICL7660-MAX1044.pdf

[/tilted/]

Hey ho.

Just a little curious what the MAX1044/ICL7660 is for?

- It isn't need for negative contrast, since this LCD uses a positive contrast Vo (check the eBay listing)...

- It certainly won't provide the kind of 400Hz, 100V supply required to run the EL backlight...

So what is it for?

I've used some EL LCDs before with the CORE board before. The contrast pot works as normal, but the LED brightness pot is of course usless, as you must use an inverter to supply the EL. (I used the one found elsewhere on eBay, intended for use in fancy after-market auto dashboards, if it helps...)

[napierzaza]

Well that's enlightening. I couldn't find anything about these displays so that changes quite a bit. They guy selling them had no info on the actual backlight wiring. I found some info on this forum but no one mentioned EL backlights, the internet totally failed me. I found one site with a schematic for but they never actually explained what the supply was (though it looked way different than -2 volts mind you).

[/tilted/]

This is the model I used:

http://cgi.ebay.com/ebaymotors/EL-GLOW-GAUGES-INVERTER-ACURA-INTEGRA-LEGEND-VIGOR-TL_W0QQcmdZViewItemQQcategoryZ43952QQihZ020QQitemZ300239165950QQrdZ1QQsspagenameZWDVW

Hope this helps.

[napierzaza]

Thanks, I bought it. I hope the display istself works too. :-/

[/tilted/]

FWIW: I also did not connect the LED pins on the LCD board.

Ordinarily the core board drives the two LED pins A and K via the brightness pot, etc.

Since the LCD I used in this case was EL backlit, these pins are not needed. To ensure that the LCD didn't put noisey 400Hz tone on the A and K lines, I disconnected them. Probably not needed, but there you go.

Also: please do be very careful of the voltage out of the inverter.

[napierzaza]

Certainly thanks for the info.

Considering this requires a 12 volt DS input, is it advisable to connect it to my SID (6851) PSU? Or will this also add noise? I'm not certain I have space to make another 12v power supply.

[/tilted/]

It should be sufficient to attach the inverter to the 12v supply you have.

At worst, you might get some back-EMF hash, but this should be cleaned up by the existing filter capacitors.

If not, you could add an LC choke/capacitor network to isolate the inverter, but we'll jump off that bridge when we come to it.  ;)