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Precision clock: Both LEDs on back are off when powered on
Elaq Posted: 24 Jan 2022, 02:56 PM
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Posts: 2
Joined: 24-January 22
I assembled my clock kit and it doesn't seem to be able to get a GPS fix. When I plug it in, both LEDs on the back stay off even though the one on the NEO-6M module should be lit.

(User posted image)


The segments on the front seem to work fine but they just count up.

Reseating the ATTINY didn't fix this and everything seems to be soldered correctly.
Is it possible that the firmware on the NEO-6M or the ATTINY is not working correctly?

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On an unrelated note, I noticed that +5V on the white barrel jack was wider than the other pins and didn't fit in the hole correctly. I had to make the pin smaller by cutting it on either side.
(User posted image)


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mit Posted: 24 Jan 2022, 05:19 PM
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yeah whatever

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It's overwhelmingly likely to be a soldering error on the GPS module header. I test every GPS module before shipping now, so I can confirm the firmware on it is OK. The best bet is to investigate with a multimeter.

First check whether 5V is reaching the GPS module, measuring its VCC and GND pins while the clock is turned on.

If that's fine, then check for a short between some of the other pins. While the clock is turned off, continuity check each of the GPS pins with adjacent ones. A short between e.g. PPS and RXD can cause the module to hang.

If you find a problem, it can be quite tricky to fix, you may have to unsolder the digit in front of the header. Or, if you can't find a problem, I'll have a think about what else it could be.

QUOTE
On an unrelated note, I noticed that +5V on the white barrel jack was wider than the other pins and didn't fit in the hole correctly.
Sorry about that. The supplier I use for the barrel jacks was out of stock recently, and I chose the white ones thinking they were identical except for the colour. I tested the cable fitted into them fine, but didn't think to check the pin width.

I will add a note to the assembly instructions about it.



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Elaq Posted: 24 Jan 2022, 07:57 PM
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Joined: 24-January 22
Only 0.7V are reaching the module. I'll check the joints under the segments later because my desoldering braid doesn't really work too well, and I need to wait for a desoldering pump to arrive.

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