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Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Mon Jan 29, 2024 4:39 pm
by 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!
Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Tue Jan 30, 2024 3:35 am
by 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?
Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Tue Jan 30, 2024 4:13 am
by VK3KYY
W7OBB wrote: ↑Tue Jan 30, 2024 3:35 am
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
Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Sat Feb 03, 2024 7:05 pm
by 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
Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Sat Feb 03, 2024 7:50 pm
by VK3KYY
W7OBB wrote: ↑Sat Feb 03, 2024 7:05 pm
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
Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Thu Feb 08, 2024 9:48 am
by SQ1TAO
I really Thank You for guide how add GPS to GD77
I have question,
bold satellite number is for Beidou system?
Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Thu Feb 08, 2024 10:13 am
by SA0BUX
SQ1TAO wrote: ↑Thu Feb 08, 2024 9:48 am
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.
Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Thu Feb 08, 2024 10:20 am
by SQ1TAO
F1RMB wrote: ↑Thu Oct 12, 2023 1:50 am
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.
Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Thu Feb 08, 2024 10:48 am
by F1RMB
SQ1TAO wrote: ↑Thu Feb 08, 2024 10:20 am
F1RMB wrote: ↑Thu Oct 12, 2023 1:50 am
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
Re: GPS (GP-02) kit module fitted in a GD-77
Posted: Thu Feb 08, 2024 10:53 am
by SQ1TAO
F1RMB wrote: ↑Thu Feb 08, 2024 10:48 am
SQ1TAO wrote: ↑Thu Feb 08, 2024 10:20 am
F1RMB wrote: ↑Thu Oct 12, 2023 1:50 am
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