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634 USB V2.2 just went dead

DasGnu

New member
Hi there!

A while ago I bought a 634 USB display.

While all went well for quite some time now this morning the display just went dead during a PC reboot. I mean, really dead. When plugged in it doesn't light up, it's not recognized by windows any more (neither the display, nor the USB-COM-Port), the status-led for the port on the hub doesn't light up, nothing.... (--> dead!)


Since the cable is ok and the display itself doesn't even get power I suspect it's just the USB-addon-board, and since returning the display for repair is not exactly an option due to the outragous shipping costs (spent 34$ on delivery last time including taxes and what not) and I'm pretty good with a soldering iron I took the liberty of completely disconnecting the addon-board from the display.
I gently soldered out the connections from J2 (with low heat), And the glue under the logo came off quite easily, too, so I'm pretty sure I didn't damage the main display board or any of it's components.

Now of course the question is, how can I get the display back up and running?

The easiest way for me would be to convert it to a serial display, I assume this is possible by adjusting the setting of JPA thru JPL.

Would you perhaps be so kind to tell me the correct setting for my display to re-enable the serial port?


If that's not an option (or turns out not to be doable) what about buying just a replacement USB-addon-board (I've got 632634v2.0 now)? Would it be possible to get such a board (as a replacement part), so I can solder it back on myself without having to send the entire display across the ocean AGAIN? What would the charge be?
My display is a 20x4 black positive display with white backlight, it says SKD204-634 V2.2 on the back.


Thanks for your help :)
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DasGnu

New member
Ok, thanks for the specs, I managed to clear the jumpers, now all I need is a cable! I'll get to that in a few days, then we'll see wether the display survived :)
 

Saus

New member
Same problem over here, and I want to do exactly the same thing because I don't feel like sending stuff ;)

Could i get perhaps get the specs too? My dad is extremely handy with these things (i hope)

:)

Thanks in advance!
 
USB LCD Displays - Graphic and Character LCDs with a Keypad

DasGnu

New member
The specs for the specific jumper setting depends on the kind of display you have (positive/negative etc...)

There's a table printed onto the back of the main PCB detailing the settings of each jumper and what they are for, the setting that worked for me was "all clear".

My display is back up and running by the way!


Oh, two little words of advice:

1. DO NOT TWIST or otherwise bend, stretch or pressurize the board while trying to get the daughterboard off! You'll fracture it and create broken contacts!

2. Do not heat up the board more than absolutely neccessary and never more than a few seconds at once while soldering out the contacts or you'll damage the polarization filter of the display and/or the ICs! Use a soldering iron with temperature control and don't push it to 450°C where 275°C will do!

Basically what I'm trying to say is: this layout uses quite sensitive SMD technology. Don't just tear the thing apart and don't fry it, either!

Good luck!

While we're at it: I don't take any responsibility for the correctness of this information. It worked for me, but if you chose to try it yourself then that's YOUR decision and what ever happens because of it is YOUR problem...
 

Saus

New member
DasGnu said:
While we're at it: I don't take any responsibility for the correctness of this information. It worked for me, but if you chose to try it yourself then that's YOUR decision and what ever happens because of it is YOUR problem...
No worries he'll prolly knows what to do when he reads it.

And besides, at this moment it doesn't work either :)
 
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