K5synth

From: Matthew <formanmatthew@...>
Subject: [k5synth] Better LCD + backlight replacement option.
To: k5synth@yahoogroups.com
Received: Saturday, July 9, 2011, 4:16 PM


  



Hi fellow K folks,

Just recently got hold of a K5m in pretty good condition after having been after one at a decent price for ages. Just one issue: you guessed it - no backlight!

As seems to be pretty common, both the inverter and EL film are dead. Rather than fiddle around with replacement film and inverter, I obtained a compatible LCD module with a yellow/green LED backlight. I did a bit of work to make sure it should be compatible (eg. that the PSU had spare capacity to drive the LEDs), and I've just installed and tested it. Results? Great! See pic here:

https://www.dropbox.com/gallery/4052505/1/K5m?h=2f0eb8

It's not *really* bright, but it's a transflective unit, so good contrast even with high ambient light. *Much* better viewing angle than the original, too.

I thought it'd be worth a shot - the LED solution ought to be much more reliable than inverter+EL film backlight, and of course no irritating HF whine..

Anyway, if you're interested in getting one of these - USD30 or GBP18.50 +shipping - let me know. Fitting is a bit fiddly (desoldering/replacement of 20 Way IDC header), but as a pro electronic engineer and amateur synthesist I'd like to help people out if I can. I could fit (including the extra components), connect to the PSU and test in my spare time for a very modest fee.

This group looks to be a good community and resource (Service Manual was particularly helpful - thanks somethingkillingyou). Hope I'll be able to put something back into it!

Matt

>
> 
> 
> --- In k5synth@yahoogroups.com, Michael Dunn <md@> wrote:
> >
> >     At 4:16 PM +0000 7/9/11, Matthew wrote:
> > >This group looks to be a good community and resource (Service Manual 
> > >was particularly helpful - thanks somethingkillingyou). Hope I'll be 
> > >able to put something back into it!
> > 
> >    You could do that by telling us where to get the displays. I'm not 
> > interested in a middleman...
> >
> 
> Woah! So that's what you get for trying to be helpful around here.
> 
> Not particularly interested in /being/ a middleman (or making any money, if that's what you were wondering). Compatible displays are all over the place - just check eBay, for example. But that's exactly the point..
> 
> In a few posts on here, people are asking 'might this display work?', 'is this one compatible?', etc. I was just trying to offer the benefit of my experience (20 yr. professional electronics/systems R&D engineering) to save other folks here from guesswork and offer a solution that actually worked.
> 
> If you want to do it yourself, go ahead.. Get hold of the manufacturer data sheet for the part you're looking at though, and do a bit of research first.
> 
> Things to worry/not worry about:
> 
> * LCD drive voltage (check data sheet) will generally always be within the range that the 'contrast' pot supports - the pot's just part of a potential divider that puts out a pretty wide range between about -5 and -15 V. So don't worry about that.
> 
> * Provided it's a 240x64 display with a Toshiba T6963C controller and standard 2x10 pin hardware interface (compare data sheet with K5 service manual schematic), it should work fine.
> 
> * For an EL backlight with similar drive needs to the original, just wire to the/an inverter; for an LED backlight as I'd recommend, first check on the data sheet that the LED string doesn't need more than about 400mA forward current (that was about the spare capacity of the 5V line on my K5m PSU, at least - best measure yours especially if a K5). Then, considering the LED forward voltage (also on data sheet), calculate a series current limiting resistor value to suit. Get a suitable resistor and wire it all up to the 5V supply line.
> 
> * Some units (eg. with LED backlights) will be a bit thicker than the original - I just put some extra nuts/washers on the standoffs as spacers. There's still plenty of space in the K5m for the PSU board to be a few mm further back.
> 
> As I said, if anyone wants help with any of this hardware stuff then I'd like to do what I can. Possibly less so if all that comes back is 'attitude', though.
> 
> M.
>

----- Original Message -----

From: steveporter258

To: k5synth@yahoogroups.com

Sent: Monday, April 16, 2012 12:22 AM

Subject: [k5synth] Re: Better LCD + backlight replacement option.

would'nt it be easier just to put a link to the website where you got yours from instead of all the tech info about what to look for?
It is a bit strange that you state your an electronics engineer and then state you know an electronics guy who could wire the 20 pin connections for a little fee.
Sounds like you don't really want to help,but instead are looking to make a few quid.
--- In k5synth@yahoogroups.com, "Matthew" wrote:
>
>
>
> --- In k5synth@yahoogroups.com, Michael Dunn wrote:
> >
> > At 4:16 PM +0000 7/9/11, Matthew wrote:
> > >This group looks to be a good community and resource (Service Manual
> > >was particularly helpful - thanks somethingkillingyou). Hope I'll be
> > >able to put something back into it!
> >
> > You could do that by telling us where to get the displays. I'm not
> > interested in a middleman...
> >
>
> Woah! So that's what you get for trying to be helpful around here.
>
> Not particularly interested in /being/ a middleman (or making any money, if that's what you were wondering). Compatible displays are all over the place - just check eBay, for example. But that's exactly the point..
>
> In a few posts on here, people are asking 'might this display work?', 'is this one compatible?', etc. I was just trying to offer the benefit of my experience (20 yr. professional electronics/systems R&D engineering) to save other folks here from guesswork and offer a solution that actually worked.
>
> If you want to do it yourself, go ahead.. Get hold of the manufacturer data sheet for the part you're looking at though, and do a bit of research first.
>
> Things to worry/not worry about:
>
> * LCD drive voltage (check data sheet) will generally always be within the range that the 'contrast' pot supports - the pot's just part of a potential divider that puts out a pretty wide range between about -5 and -15 V. So don't worry about that.
>
> * Provided it's a 240x64 display with a Toshiba T6963C controller and standard 2x10 pin hardware interface (compare data sheet with K5 service manual schematic), it should work fine.
>
> * For an EL backlight with similar drive needs to the original, just wire to the/an inverter; for an LED backlight as I'd recommend, first check on the data sheet that the LED string doesn't need more than about 400mA forward current (that was about the spare capacity of the 5V line on my K5m PSU, at least - best measure yours especially if a K5). Then, considering the LED forward voltage (also on data sheet), calculate a series current limiting resistor value to suit. Get a suitable resistor and wire it all up to the 5V supply line.
>
> * Some units (eg. with LED backlights) will be a bit thicker than the original - I just put some extra nuts/washers on the standoffs as spacers. There's still plenty of space in the K5m for the PSU board to be a few mm further back.
>
> As I said, if anyone wants help with any of this hardware stuff then I'd like to do what I can. Possibly less so if all that comes back is 'attitude', though.
>
> M.
>