GPS (GP-02) kit module fitted in a GD-77

[BD4SMY]

LY1RF, Thank you very much about the soft wire!

About my question 1 & 3, whether I'm right or not, please no hesitate to let me know.

Thanks a lot again!

[W7OBB]

Well after much testing it appears I bricked by GD77. Not sure if I shorted something out or what happened but I removed all my changes and it still won't power up. Any suggestions for how to find the issue?

[VK3KYY]

Well after much testing it appears I bricked by GD77. Not sure if I shorted something out or what happened but I removed all my changes and it still won't power up. Any suggestions for how to find the issue?

There is a fuse inline with the battery input. Check you have not blown it

[W7OBB]

Fuse was okay.

I found a voltage regulator labeled 4B2F (the one I was trying pull power from for the gps module) has a short to ground on pin 5 which should be the voltage out. So I think that’s my problem. Does that make sense?

I found 4B2X and 4B2K regulators on Ali express. They all seem to have the same spec sheet. Can I use them to replace my 4B2F?

https://product.torexsemi.com/system/fi ... xc6205.pdf

[VK3KYY]

Fuse was okay.

I found a voltage regulator labeled 4B2F (the one I was trying pull power from for the gps module) has a short to ground on pin 5 which should be the voltage out. So I think that’s my problem. Does that make sense?

I found 4B2X and 4B2K regulators on Ali express. They all seem to have the same spec sheet. Can I use them to replace my 4B2F?

https://product.torexsemi.com/system/fi ... xc6205.pdf

Yes, that makes sense

I would order some regulators and replace the one which you shorted


Edit.

I can't find any information about that part number

Did you try removing the short ?

I can't remember if the GD77 only has one regulated rail , which would be 3.3V . I recall that possibly some older radios may have 5v and 3.3V rails,

After removing the short, check if that regulator feeds the Flash chip, because it's pins are easy to access

[SQ1TAO]

I really Thank You for guide how add GPS to GD77
I have question, bold satellite number is for Beidou system?

[SA0BUX]

I really Thank You for guide how add GPS to GD77
I have question, bold satellite number is for Beidou system?

Or other satellites than the ones from USA, normally it would be different colors but I guess they use bold on the monochrome display.
I have to look on the tracking map to see if Beidou satellites go over Europe a lot.

On the UV380 | RT-3S | DM-1701 RT-84 the GPS satellite RSSI bar graphs are colour coded. By default, Blue is for USA GPS Satellites and Red is for other satellite systems.

[SQ1TAO]

The power control is done using a N-Channel MOSFET (AO3400, cheap and I have plenty), and 2 resistors (300kΩ between Source and Gate, 200Ω on the Gate line).

I use to Power Control for GPS built in voltage stabilizer in GP-02 Kit. Small chip LP3992 have a ENABLE leg. So i connected to CPU and seems to disable power to GPS+BDS module when is OFF in software.

[F1RMB]

The power control is done using a N-Channel MOSFET (AO3400, cheap and I have plenty), and 2 resistors (300kΩ between Source and Gate, 200Ω on the Gate line).

I use to Power Control for GPS built in voltage stabilizer in GP-02 Kit. Small chip LP3992 have a ENABLE leg. So i connected to CPU and seems to disable power to GPS+BDS module when is OFF in software.

Already commented upper in the thread: viewtopic.php?f=13&t=3365&start=10#p27340

[SQ1TAO]

The power control is done using a N-Channel MOSFET (AO3400, cheap and I have plenty), and 2 resistors (300kΩ between Source and Gate, 200Ω on the Gate line).

I use to Power Control for GPS built in voltage stabilizer in GP-02 Kit. Small chip LP3992 have a ENABLE leg. So i connected to CPU and seems to disable power to GPS+BDS module when is OFF in software.

Already commented upper in the thread: viewtopic.php?f=13&t=3365&start=10#p27340

Not NF pin, look at GP-02 kit board and to small LP3992 module on this