Electronics > Repair

Samsung LCD - Weird Failure - Trying to Repair

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katzohki:
I have a weird failure with this Samsung 215TW. Let me start off by stating what I've done:
I replaced the bad caps (bloated CapXon) on the power supply board and checked voltages at the local regulators. Everything looks good with voltage, but no fix yet. I also checked over the main board for bad solder joints and other physical maladies.
Here's a picture of the strange glitch:

As you can see, it looks pretty scrambled. This should be something like a message stating "no source found" or something like that. It floats around the screen. And when I try to change inputs, it pops up into the upper-left corner where the input message box would normally be. Besides that, I haven't got video when testing the inputs. To be fair, and you can beat me up over this if you want, I have only tested the VGA input. But I really don't think that's going to be the issue because something looks wrong besides input. I'm thinking it's a communications issue somewhere on the main board. There is a service manual available online that details the schematics of the monitor.

Any ideas?

AndyC_772:
Looks like there's some dual port RAM that's not getting written.

katzohki:
Hm, there's a 128M SDRAM chip, but it looks like the only thing writing to it is the main ADC / Prescaler / LVDS. I'll see if I can give it a probe.

fluxcapacitor:
It looks like the eeprom is corrupt to me .

tautech:
In VGA source mode are you supplying a PC video signal?
Maybe your card won't recognize it?

What was the original fault?

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