Cat5 Video Rx Unit

[olliez0r]

Hi guys,

Long time reader first time poster etc etc...

My knowledge is pretty sparse but I'm confident when armed with a small amount of knowledge

Got a UTP video Tx/Rx (not IP/switched) set at work for sending VGA over large distances.

Had two of the Rx units fail - they're supposed to receive power over the UTP cable (direct from the Tx unit), but can take 12v separately; have tried and the LED doesn't light and video signal doesn't work under either condition.

I'd like to think it's as simple as a fuse on the board, but there's some components that I'm not sure how to identify.

Picture attached - the component in the bottom right does not have continuity - could this be it? The (assuming) fuse under the DC jack is fine, but I wouldn't expect this to have any impact on the standard power input anyway.

Any advice is appreciated; work can't afford to buy replacements for these as they're surprisingly expensive.

Cheers,
Ollie

[macboy]

The component circled in red is a fuse. It should read at most a few ohms, in either direction.

The component circled in green is a reverse protection diode. If power is connected backwards, then this short circuits the power supply (preventing reverse voltage reaching the devices) and blows the fuse. In one direction, this diode should measure something around 600 mV (+/- 200 mV) using the diode test of your multimeter. In the other direction it must measure as open. If shows continuity in both directions, it is bad. If it doesn't measure good (~ 0.6 V) in the forward direction, it is bad.