All,
Troubleshooting an APC NetBotz 455 environmental monitoring device. I've had this on my "to fix" shelf for a while and got a hair tonight to look at it. Did some standard troubleshooting first...visibly inspected the boards, no blown caps, no burn marks, nothing "appears" out of the ordinary. Re-seated what would be considered the motherboard, checked the CMOS battery for proper volts, nothing else is jumping out at me.
Got out my multimeter and started probing points on the board that were labeled with voltage readings.....getting nothing other than small blips. This is a POE device and plugged into my midspan it just cycles power quickly on, then off for several seconds, over and over. Decided to get away from the midspan and used a dumb POE injector. Started getting rapidly fluctuation voltage readings and the same points I was measuring before, plus noticed a could LED lights on the board rapidly flashing. Next I was going to start working my way up the board from the power source (network cable) and went to test my first voltage regulator on the board and suddenly the lights when solid and it booted up. Unsure of what I did I cut power and tried again....same thing.....quickly flashing lights. Tried testing the voltage regulators that I "thought" I had started with but just kept getting fluctuating readings again. Moved to what I thought was a smaller VR and touched the negative probe of my multimeter to pin one, and it started booting up again.
Since figuring out what I did this is very repeatable. I don't need both leads on the multimeter, just need to touch one of the leads to pin one on the IC, which looking closer is not a VR, but is a bi-polar transistor. New to me....I know what transistors are, but never heard of a bi-polar transistor. I've included a couple pics showing a larger view of the board(s) as well as a close up of the bi-polar transistor in question. Below is a data sheet link I found for this transistor:
https://cdn.badcaps-static.com/pdfs/...22bcc52bd3.pdf
If someone could be so kind as to take a look at the datasheet and the pics, and give me your thoughts. Still getting my feet wet at component level repair with anything greater than re-capping a board or working with resistors and diodes....I can't believe it would be as simple as replacing the bi-polar transistor, and won't be surprised if it's believed to be another component and I just discovered a symptom/by-pass.
Thanks!!!
Troubleshooting an APC NetBotz 455 environmental monitoring device. I've had this on my "to fix" shelf for a while and got a hair tonight to look at it. Did some standard troubleshooting first...visibly inspected the boards, no blown caps, no burn marks, nothing "appears" out of the ordinary. Re-seated what would be considered the motherboard, checked the CMOS battery for proper volts, nothing else is jumping out at me.
Got out my multimeter and started probing points on the board that were labeled with voltage readings.....getting nothing other than small blips. This is a POE device and plugged into my midspan it just cycles power quickly on, then off for several seconds, over and over. Decided to get away from the midspan and used a dumb POE injector. Started getting rapidly fluctuation voltage readings and the same points I was measuring before, plus noticed a could LED lights on the board rapidly flashing. Next I was going to start working my way up the board from the power source (network cable) and went to test my first voltage regulator on the board and suddenly the lights when solid and it booted up. Unsure of what I did I cut power and tried again....same thing.....quickly flashing lights. Tried testing the voltage regulators that I "thought" I had started with but just kept getting fluctuating readings again. Moved to what I thought was a smaller VR and touched the negative probe of my multimeter to pin one, and it started booting up again.
Since figuring out what I did this is very repeatable. I don't need both leads on the multimeter, just need to touch one of the leads to pin one on the IC, which looking closer is not a VR, but is a bi-polar transistor. New to me....I know what transistors are, but never heard of a bi-polar transistor. I've included a couple pics showing a larger view of the board(s) as well as a close up of the bi-polar transistor in question. Below is a data sheet link I found for this transistor:
https://cdn.badcaps-static.com/pdfs/...22bcc52bd3.pdf
If someone could be so kind as to take a look at the datasheet and the pics, and give me your thoughts. Still getting my feet wet at component level repair with anything greater than re-capping a board or working with resistors and diodes....I can't believe it would be as simple as replacing the bi-polar transistor, and won't be surprised if it's believed to be another component and I just discovered a symptom/by-pass.
Thanks!!!
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