Internal GPS Mod Tech Support/Q&A

[jonwienke]

Here's a video.
https://1drv.ms/v/s!ApJIS-l4xqPtgtxA5SYYKzyJBosLiw

And a photo showing the power switch. It also switches the GPS data line (yellow wires) so you can use an external GPS when the internal unit is turned off.
https://1drv.ms/u/s!ApJIS-l4xqPtgukYtiFimPTCLgzQwA

The current version of the mod also has GPS power and satellite fix LEDs on the rear case, just above the patch antenna.

 

[AronDouglas]

I purchased a globalsat BR-355S4, and it's power requirements say anywhere from 4.5-6.5V. Is it safe to tap a 6V line then? Because there is a 6v point on the board already. If not, then I was going to integrate a simple circuit (12v to 5v) tapping off of the main input power, and supplying it to the DB9 via the scanner pin 9.

 

[jonwienke]

If the BR-355S4 specs say it can handle 6.5V DC power continuously, then 6V is fine.

 

[AronDouglas]

Well, so far so good. 6v power tap is working for the BCT15X.

https://lh3.googleusercontent.com/-...Cw/h1152/7547424399247478801%3Faccount_id%3D0


https://lh3.googleusercontent.com/-...Cw/h1152/3699977778051000425%3Faccount_id%3D0

 

[jonwienke]

Cool!

I would suggest not running the scanner without the GPS going forward, because if you stuck a penny or paper clip in the GPS port and shorted out pin 9, the scanner probably wouldn't like it.

 

[jonwienke]

Here's some step by step photos of the 436 internal GPS mod:

https://1drv.ms/i/s!ApJIS-l4xqPtgukaBGSTOGwPfRcasA
The GPS module and power switch installed in the rear case. Note the ferrite toroid installed on the GPS harness. The power and data wires are threaded through the ferrite to suppress common-mode currents.

https://1drv.ms/i/s!ApJIS-l4xqPtgukbVO05Mr1JOGARCw
The wiring harness attached to the rear circuit board. The longest 2-pin plug goes to the GPS status indicator LED. The 6-pin plug goes to the GPS module. The other plugs go to the switch (red wires are GPS power, and yellow wires are serial data).

https://1drv.ms/i/s!ApJIS-l4xqPtgukdbTefr6fsaHZUDw
The rear circuit board is connected to the GPS module.

https://1drv.ms/i/s!ApJIS-l4xqPtgukYtiFimPTCLgzQwA
The rear circuit board is installed in the rear case, and the power and data wires are connected to the switch and the front and rear circuit boards. The GPS status indicator is not yet connected.

https://1drv.ms/i/s!ApJIS-l4xqPtguke4qm96UDspYCWdw
The front circuit board screwed in place, and the front panel GPS status indicator LED is connected. This view is from the scanner right; most of the other photos are from the scanner's left side.

https://1drv.ms/i/s!ApJIS-l4xqPtgukfKnN_MKx6_XrvfQ
The completed mod.

 

[tomas4569]

Here's some step by step photos of the 436 internal GPS mod:

https://1drv.ms/i/s!ApJIS-l4xqPtgukaBGSTOGwPfRcasA
The GPS module and power switch installed in the rear case. Note the ferrite toroid installed on the GPS harness. The power and data wires are threaded through the ferrite to suppress common-mode currents.

https://1drv.ms/i/s!ApJIS-l4xqPtgukbVO05Mr1JOGARCw
The wiring harness attached to the rear circuit board. The longest 2-pin plug goes to the GPS status indicator LED. The 6-pin plug goes to the GPS module. The other plugs go to the switch (red wires are GPS power, and yellow wires are serial data).

https://1drv.ms/i/s!ApJIS-l4xqPtgukdbTefr6fsaHZUDw
The rear circuit board is connected to the GPS module.

https://1drv.ms/i/s!ApJIS-l4xqPtgukYtiFimPTCLgzQwA
The rear circuit board is installed in the rear case, and the power and data wires are connected to the switch and the front and rear circuit boards. The GPS status indicator is not yet connected.

https://1drv.ms/i/s!ApJIS-l4xqPtguke4qm96UDspYCWdw
The front circuit board screwed in place, and the front panel GPS status indicator LED is connected. This view is from the scanner right; most of the other photos are from the scanner's left side.

https://1drv.ms/i/s!ApJIS-l4xqPtgukfKnN_MKx6_XrvfQ
The completed mod.

What's the resistor right above the GPS module battery for?

Roger BEEP!

 

[jonwienke]

It limits the front panel GPS status indicator LED current to about 1mA. It's bright enough to be seen in daylight without affecting battery life significantly.

 

[I_am_Alpha1]

Hey Jon,

Super work here...would you please post a list of parts and numbers. I'd like to give this a shot. I don't want to cut the case, so a bit tricky to make it work. I was hoping the GPS with detachable antenna worked, would have been perfect.

 

[jonwienke]

would you please post a list of parts and numbers. I'd like to give this a shot. I don't want to cut the case, so a bit tricky to make it work.

You can't do the mod without cutting the case. The GPS module will not physically fit in the available space inside the 436 without the cutout. And all the other GPS modules I've tried (over a dozen) cause some degree of RFI trouble.

I use a drill press with an X-Y table and digital position readouts for the X, Y, and Z axes to make the cutout. This enables me to precisely locate and size the cutout for the patch antenna and the holes for the LED indicators in the rear case, so that the GPS module fits in the cutout properly, the status LEDs align properly with their holes, and the module doesn't short against any of the other components in the scanner. I use a 1/4-inch diameter 2-flute end mill for the antenna cutout (that's how I get the corners of the cutout rounded to match the contour of the patch antenna), and a 3/32" drill for the rear LED holes.

The rest of the process is more straightforward, and can be replicated by anyone with decent soldering skills and basic hand tools.

The GPS connector is a 6-pin JST 1.25mm, and the LED connector can be a 2 or 3-pin JST 1.25mm. The power switch connectors are 2-pin JST 2.0mm female connectors with the tips cut off as shown in the 4th photo (I have to trim the switch pins to allow the rear circuit board to fit in place, so part of the connector must be cut off for the connector to engage the pins). The The RFI suppression toroid has a 6mm OD, 3mm ID, and is 2mm thick.

The power switch is a 5.8mm latching DPDT pushbutton with 2mm pin spacing.

The front panel status LED is a standard clear 3mm LED, which I grind flat so that is sits flush with the front case, and has a frosted finish so the light shines more uniformly in all directions). I choose resistor values to keep the LED current around 1mA, which makes it bright enough to see in daylight without causing excessive battery drain.

I use Liquid Nails to glue the power switch in place, and clear DAP window caulking (not silicone based) to glue the GPS module and the front panel LED in place. That allows the rear LEDs on the GPS modules to be visible--I let it fill the holes and act as a light pipe.

 

[I_am_Alpha1]

I really want to keep the ability to hang the scanner from the mic clip in my car. Unfortunately Uniden didn't include GPS...they could have bought them in bulk for a buck or two and widened the case a mm or 2.

Anyway, I could remove the batteries and put the GPS in the battery compartment...plenty of open space around the terminals to run the wires inside. Only need three (+, -, & Data). Would be nice to include a plug of sorts to pull the GPS out and put batteries back.

Or, I could mount the GPS on the outside of the battery cover and add a 3d printed box over it, clear or neutral, so the LEDs would show. Drill a small hole and run the three wires into the battery compartment and around the batteries. I don't take my 536 anywhere, but if I did I'd do something like this--but it on the back and make a box to cover it and the DB9.

 

[jonwienke]

Or you could mod the scanner in such a way that you can still run it on batteries, and get the ScannerMaster 436 case that has a much sturdier metal belt clip stud than the plastic factory one, and offers significant protection to the scanner. And you can still hang it from the mic clip.
https://www.scannermaster.com/BCD436HP_Uniden_Nylon_Case_Swivel_Belt_Clip_p/01-581859.htm

As to the 536:
https://forums.radioreference.com/u...ernal-gps-mod-tech-support-q.html#post2792617

https://forums.radioreference.com/u...ernal-gps-mod-tech-support-q.html#post2797545

https://www.radioreference.com/apps/classifieds/showproduct.php?product=8647

 

[I_am_Alpha1]

I did the mod and it works great. I didn't cut the scanner back...instead I make a small notch in the battery compartment next to the SD card for the wires. The wiring now sits in the battery compartment..I can either remove the batteries and put the GPS module in their place (wrapped in foam), or (my next step) cut a small notch in the top of the battery cover and run the wires out and 3d print a small box for the GPS module to velcro/glue to the back of the battery cover (extra cover is $15). Note in the pictures I did the battery charge mod as well and it's wonderful. I use energizer 2300 MaH NiMH and they draw around 58-60 ma to charge.

My 436 sits in it's stand 90% of the time...now when I travel I don't need to lug the GPS puck, power adapter, and on and on and on. Plug in the GPS module and go...and no more dead batteries I unplug it.

THANX TO JONWIENKE...Uniden Employee of the Year!

 

[jonwienke]

I did a GPS install on a HP-2, and ran into a curious issue. There are labeled test pads near the GPS jack similar to the 436, but they are NOT all correctly labeled. The TXD and RXD pads are labeled backwards, so the scanner receives incoming GPS data on the pad labeled TXD. Here's a photo:

https://1drv.ms/u/s!ApJIS-l4xqPtgup-VZgtd_fh1co4UQ

If you look in the upper left corner, there is a pad labeled VBUS, and another pad center left labeled V_USB. Both are directly connected to the +5V terminal of the USB jack. Whoever made the lableing template for this board appears to be dyslexic or something.

The HP-2 is very cramped inside (even more so than the 436 and the HP-1), but I was able to fit the Reyax GPS into it after making a cutout in the case:

https://1drv.ms/u/s!ApJIS-l4xqPtgup9Tq9rjfAh9KnhLw
https://1drv.ms/u/s!ApJIS-l4xqPtgup8skMODvZVejz3LQ

I added a front-panel GPS status LED to indicate when the unit has satellite lock.

https://1drv.ms/u/s!ApJIS-l4xqPtgup7Dv4UPY0dJ54FeQ

I wasn't able to find a place with enough room for a power switch for the GPS, so I wired it direct. The HP-2 uses significantly more power than the 436 (about 300mA vs. 200mA), so the effect on battery life is less than 10% by adding the GPS. The display backlight settings have more of an effect on power consumption than the GPS.

 

[jonwienke]

On a related note, here is a link to the spreadsheet I use to make the cutouts for the GPS and Li-ion battery charger board:

https://1drv.ms/x/s!ApJIS-l4xqPtgup_zxqtNGZ7CCxghg

Notes:
All dimensions are in millimeters.

Dotted lines connecting points indicate the tool needs to cut between those points.

Numbers in parentheses in the legend indicate the depth the tool should cut. If no depth is specified, then the cut needs to go all the way through the scanner case.

X-Y zero for the 436 GPS cutout is the center of the circular mold mark on the back of the case above the belt clip screw hole. Y axis values increase going toward the bottom of the case. Z axis values increase going toward the rear of the case.

X-Y zero for the HP-2 GPS cutout is the lower left screw hole in the rear case used to secure the rear circuit board to the rear case. Z zero is the surface of the case in the center of the GPS cutout area. Y axis values increase going to the right of the case. Z axis values increase going to the front of the case.

For entertainment purposes only, not responsible for errors or omissions, measure twice, cut once, etc.

 

[Electromatic]

Great work looks fantastic!

 

[ResQguy]

My 436 seems to be unable to lock onto a satellite lately. The green LED comes on and GPS shows on the display, but the light stopped blinking and the scanner never updates its location. I’ve considered sending it back in for the latest model chip and the charging update.


Sent from my iPhone using Tapatalk Pro

 

[tomas4569]

My 436 seems to be unable to lock onto a satellite lately. The green LED comes on and GPS shows on the display, but the light stopped blinking and the scanner never updates its location. I’ve considered sending it back in for the latest model chip and the charging update.


Sent from my iPhone using Tapatalk Pro

I had the same thing happen to me several times. The module is sensitive to static electricity and can be killed quite easily. The dry weather doesn't help around here but so far number 4 is holding and going on it's fourth week. I insulated the module and working with liquid tape and another layer of electrical tape over the exposed antenna. So far so good.

Roger BEEP!

 

[jonwienke]

My 436 seems to be unable to lock onto a satellite lately. The green LED comes on and GPS shows on the display, but the light stopped blinking and the scanner never updates its location. I’ve considered sending it back in for the latest model chip and the charging update.

I had one other customer with a similar failure twice in a row. It turned out he had his 436 in a holster clipped to the heater vent in his vehicle, and the hot air from the heater was blowing directly on the GPS antenna, and after about 3 days in the car, the module would fail. After I replaced the GPS module the second time, I advised him to relocate the scanner elsewhere, and it's been working fine ever since.

Static electricity is also a concern. I paint the GPS antennas with truck bed liner spray to give the antenna some physical and ESD protection, but everything has its limits.

 

[ResQguy]

I had one other customer with a similar failure twice in a row. It turned out he had his 436 in a holster clipped to the heater vent in his vehicle, and the hot air from the heater was blowing directly on the GPS antenna, and after about 3 days in the car, the module would fail. After I replaced the GPS module the second time, I advised him to relocate the scanner elsewhere, and it's been working fine ever since.



Static electricity is also a concern. I paint the GPS antennas with truck bed liner spray to give the antenna some physical and ESD protection, but everything has its limits.

I’ll just chalk it up to this is a relatively experimental use of the device and these things happen. I don’t know of an occasion where mine has been subjected to extremes, but who knows. It’s still the best implementation of gps yet.


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