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Ok, I just got the GU128X32-311 last night. Cool! The display looks a lot bigger than I'd thought it'd be...especially when I hold it really close.

I'm still working on the data cable, but I'd like to do a quick test of it so I can tell if I got a working display or not, so could someone verify this stuff for me?

1) According to the url=http://forum.lcdinfo.com/viewtopic.php?t=549]spec sheet[/url], the display goes into testmode if T0 is held low for a second during power on. T0 is the middle pin on the 3-pin power connector. Holding T0 low just means connecting it to ground.

2) On the 3 wires, pin 1 will be 5 v, which I will just get by tapping the correct wire from the PC power supply (I believe the color is red, but I'll check with a multimeter). Pin 3 will be ground, which will also come from the PSU black wire. Pin 2 is T0. I will connect T0 to a momentary switch that when depressed will connect T0 to ground. If I hold this switch in during powerup, then the display should go into test mode and I'll know if it works or not. I do not need any data cables hooked up to do this.

3) The entire PCB should be mounted on something so it's not laying flat on a surface, and should not be touched while it's powered up or for some time afterwards.

4) Always keep myself grounded while touching the PCB. I do this by connecting a wire to the PC PSU frame and my skin.


Does all of that sound correct? If I do all that, I SHOULD get a display, right? I just don't want to blow it (literally). It was really tough to not try and hook it up last night, but I knew this was one time I had really better be patient.

My only other remaining question is....how do I know for SURE which pin of the 3 power pins on the PCB is pin 1? Is it labeled on the PCB? I couldn't see for sure because I was looking through the ESD bag. I want to make sure I don't get 5v and GND mixed up.....

Thanks for any help. This is certainly a fun new hobby!

1) almost correct; T0 (pin2) should be tied to GROUND for test mode, not momentary or just a second

2) PSU RED> +5v
A switch is a bit of an overkill just for the test mode. Also i do not recommend a momentary switch.
No need for datacable when trying testmode.

3) correct
4) correct

Power connector is labeled on the PCB.

This VFD is fused, so there's some room for error Most important thing is NOT to pull the power-connector on/off while the display is operating (that's why i don't recommend momentary switches)

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

I hadn't planned for any switch between the PSU and the VFD....so basically, when the PC comes on, the VFD will have power. (By the way, do I need to consider anything if I DO want to put a switch between the PC and the VFD? It would be a regular sliding switch, or toggle. I know the last page in the specs warns about removing main power while there's still signals over the data lines.....so probably I should just let it power up and down by the PC, eh?)

The switch I had planned (this one) was going to go in-between T0 and ground. The spec says:
.
So my thought was I'll have a pushbutton switch and to enter testmode, I'll just hold the switch in while I turn the power on....wait 100mSec, and then let go. I didn't think I had to hold the line to ground once it entered testmode, so a momentary seemed to be sufficient. True, tying T0 to ground will accomplish the same thing, but I was thinking I could mount the button on the front of the plexiglass holder I make for this, whereas tying it to ground would require some kind of toggle button.

does that make sense? Do I really need to hold it to ground the entire time for it to remain in testmode, or is it just initially?

You're probably right about the switch being overkill for testmode...but I have a feeling I'm going to need to continually re-assure myself that it's not the DISPLAY that's not working right....

Thanks for all your other responses....very re-assuring. I'm sure after I smoke a few displays I'll be less nervous.

Yes best practice is to hook it up to the PC's PSU and let it stay connected at all times. I wouldn't use a switch over it's powerlines...

Perhaps i should stand corrected as i haven't read about the 100ms T0 shorting at power up
I'm just trying to pass on to you my experiences with this 311. With some other displays test modes are normally initiated by shortening a pin continously.

Good luck, should be relatively easy.

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

Gotcha, thanks for the clarification.




Oh, experiences is exactly what I want! Anyone can read a spec, but that never beats actually doing it. Certainly holding it to ground counts as > 100 mSec.

I'll try both out...I'll hook up the momentary, but first try I'll jam the button pressed so it's continual ground....then I'll also try just holding it for a little bit while powering up.

Thanks for all the help! Now I wanna go home and see this done.....

Your great help paid off!

Purtiest test pattern I've ever seen. Now I just have to finish the data cable....

And ya, just holding down the switch while powering up put it into test mode. Even though I'll probably still put the switch on the front of the plexi stand (just for looks), it really doesn't have any value, since the switch must be held at powerup, and the testmode make the VFD useless for anything else. So to use the VFD after putting it into test mode, I'd have to actually completely power down the PC. Oh well, a big red button looks cool.

Thanks again!