Repairing a network cable tester: The magic smoke has been released!

[iamdarkyoshi]

So at least something is totally fubar on this thing.


The line sniffer thing works but its really quiet.

The cable tester does not work. When in scan or test, it does this:


So I opened up the main unit (sniffer's cable test side is just a board with leds and resistors) and I found a blowhole on a little tiny package in the middle:



VERY faint LEDs on the main unit for the first couple leds. 4 and 5 stuck on on either mode on the sniffer side.

Where to go from here? What was the blown part? I am sure I have a motherboard I can steal one from like I did with my asrock motherboard when it blew up a sot23 mosfet.

[TheMG]

Looks like it's the same as Q4, with the marking "J1Y". From what I can find, that should be a 2SA1298 PNP transistor or equivalent. Nothing special. Should be easy to find a replacement. Hopefully the microcontroller isn't damaged.

Anyways, if you have no luck fixing that piece of garbage and you do a lot of work with network cabling, I'd recommend this guy:

http://www.flukenetworks.com/datacom-cabling/copper-testing/MicroScanner-Cable-Verifier

A bit on the pricey side of things (then again, nothing Fluke is particularly cheap), but it is a handy device that does so much more than those cheap cable testers. It's saved me tons of time at work troubleshooting network drops. Faults that might have taken an hour to trace down with a regular/cheap cable tester I've been able to find and repair within minutes with this thing.

And unlike the cheap units, you can safely plug it in to a live network (even with PoE), live POTS line, etc and it won't blow up.

[iamdarkyoshi]

Looks like it's the same as Q4, with the marking "J1Y". From what I can find, that should be a 2SA1298 PNP transistor or equivalent. Nothing special. Should be easy to find a replacement. Hopefully the microcontroller isn't damaged.
-snip-

I hardly do any networking. Just stuff at home. My existing tester makes this one look like a piece of professional equipment...

Anyway, thanks for the help, I will try bodging something in place, and maybe break out the rigol osmelloscope to see where the pixies are dancing

Anyway this thing was a craigslist freebie, so I am not super concerned if I can fix it or not. If nothing else the sensor probe entertains the cats when they touch the sensor