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Hi,
first off I hope you guys are well, came through Harvey OK and managed to avoid the flooding.
If you have the time, we currently have the following situation:
We started testing with battery-powering the WARP boards (as a followup to this post, with the specified batteries). This has worked rather well, except for one board where we observed the following behaviour:
1. The board started going through a boot-loop, being reset every 4-5 s. We can rule out the software as a fault, since it has been running + tested thoroughly for months now (also on the other battery powered boards). At first we suspected the battery was getting low + replaced it, which fixed it initially.
2. The next day, this boot-looping started happening again - on a nearly full battery.
3. Following this, the board powered off and is now unable to power on at all. Even the LED indicating the board is powered is staying off - independent of the used power supply.
We currently suspect that the power connector between battery + board was not soldered properly and have replaced it.
Our question would be: Could an improperly soldered connector (with imperfect contact, but still correctly wired + isolating positive + negative) cause such a hardware fault? If not, what else could be the suspect here and how do we avoid further problems with other boards?
Best Wishes.
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first off I hope you guys are well, came through Harvey OK and managed to avoid the flooding.
Thanks. We and family are fine, homes and office are dry. We got lucky - a lot of Houston fared much worse.
Even the LED indicating the board is powered is staying off
Do you mean the red LED marked D20 is off, even when a known-good 12VDC supply is connected? That's surprising - D20 is connected directly to the EXTVDD_12.0V net, which is tied to the center pin of the barrel connector with no intermediate circuits. Do you have a multimeter or oscilloscope? What's the voltage at TP10 (the 12v test point)?
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murphpo wrote:
Do you mean the red LED marked D20 is off, even when a known-good 12VDC supply is connected? That's surprising - D12 is connected directly to the EXTVDD_12.0V net, which is tied to the center pin of the barrel connector with no intermediate circuits. Do you have a multimeter or oscilloscope? What's the voltage at TP10 (the 12v test point)?
Yes, the LED D20 is staying off, with all power supplies we tested (which we ran other boards from without issue). Will test the Voltage at TP10 when I'm back in the office (probably on Monday).
Last edited by Edlmann (2017-Sep-02 05:22:09)
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Sorry for the delay, organizing a multimeter turned out to be not as trivial as it should've been.
There is no voltage between the testpoint TP10 and ground (TP9).
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0v between TP10 and GND indicates a hard short between the EXTVDD_12.0V and GND nets. The only hope of fixing that board is to clear the short. If you're lucky the short will be visible (like a solder bridge between pins of the power jack).
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A visual inspection does not reveal anything unusual, but my knowledge about the hardware side of things is limited.
Do you have any idea what could have caused such a short? How can we assure that something like this does not happen again?
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I would suggest removing the power jack, ensuring there are no solder bridges between the through-hole pins for the jack, then measuring resistance between 12V and GND. If there is still a short, it probably means some other component on the 12V net has failed. Unfortunately the process for tracing this is to remove components one-by-one until the short is cleared.
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