Ds1102e screen corruption

[ajtaji]

Hello, I have a rigol ds1102e... Bought it new 3.5 years ago.  Only used it for one Arduino project for about 20 hours. Put t in the box and up on the shelf until recently.

https://youtu.be/tApNNNzFIZk

As you can see in the video the LCD is corrupt... I took it apart as rigol wanted 250 dollars to repair it... Stopped the clock on the motherboard, LCD freezes with corruption but no jumping...

So I hook it up to my PC with Ultrascope... Screen shows fine on the PC... So rules out ram corruption...

So basically I'm thinking LCD control chip or LCD itself but I don't have a schematic...

Do you have any opinions?

Edit:  This uses the UPS051 LCD controller.

[tautech]

Welcome to the forum.

Re-seat all display connectors. Check any ribbon cables for corrosion on their ends. Clean gently with an eraser if necessary.

[ajtaji]

Thank you, after the holiday, I'll pull those ribbons off again and have a better look at them... They looked shiny and gold so I just reseated them without much thought...  I've been out of electronics repair for a number of years and more into software.

[Rasz]

you could check Vsync with another scope ;P
I played with similar LCD out of HP printer, bad news is its analog between UPS051 and tcon, good news you could probably source cheap LCD out of said HP printer, reconfigure UPS051 for low resolution and have a cheap way of discerning which is broken.

[ajtaji]

thank you for the analog info... Pointed me to the negative output on the power supply which supposed to be -12v but is only -9v... The data sheet for the lcd says Negative power for scan driver VGL -10.5min -10.0typ -9.5 Vmax.  So I'll look at the negative side of the power supply when I get more time.

[stj]

probably crap electrolytic capacitors.

[ajtaji]

Well I've taken ever cap and diode out of circuit, no bad parts.  So it looks like its in the TOP247 controller circuit or the transformer.  Looks like I wont be able to diagnose my scope without another scope as my fluke wont read any of the switching voltages.  Thanks for the help everyone.

[stj]

did you check the esr of the caps?

[ajtaji]

I did not although I replaced most with new ones... I actually believe that the guy that had drawn the PSU schematic actually had a malfunctioning unit... Because the 6.4 volt output actually is 6.4 volts and looks like the switching control for the transformer.  I have 3.3v,6.4,12v and -9v and schematic shows 15 and -12 on the latter two.   And I'm afraid to probe within the machine with it's own probes.  Things with my limited equipment and knowledge appear to be in working order on the PSU.

[tautech]

I did not although I replaced most with new ones... I actually believe that the guy that had drawn the PSU schematic actually had a malfunctioning unit... Because the 6.4 volt output actually is 6.4 volts and looks like the switching control for the transformer. I have 3.3v,6.4,12v and -9v and schematic shows 15 and -12 on the latter two.   And I'm afraid to probe within the machine with it's own probes.  Things with my limited equipment and knowledge appear to be in working order on the PSU.

More likely it's the mains AC Line signal for setting a Line trigger......50 or 60 Hz.

[Gary350z]

Here are some schematics for this scope, if you do not already have them.

http://rigol.codenaschen.de/index.php/Schematics

[ajtaji]

Thank you for that link.  I had found the PSU unit drawing but other than a couple voltages being different by three volts I done nothing wrong with it without a scope... When I can afford a better scope than rigol I'll check back in here and if I did it I'll use it on automobiles and not in a lab setting.

[Rasz]

You could try swapping UPS051 before giving up, its 8$ on ebay including shipping.

[exider]

Hi ajtaji,

I have the same problem and was wondering if you got it fixed?
I have noticed that if I leave the unit to warm-up (about 5-10 min.) the LCD gets fixed by itself.
Any suggestions?


Edit: the problem was a cracked solder joint on the LCD connector. Strangely, how these defects show up after the warranty period