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Trimble Placer GPS 450 Power - Dis-assembly [message #3044] Fri, 11 July 2014 22:57
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Registered: December 2004
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I recently acquired a large quantity of the Trimble Placer 450 GPS units for my local ares/races group. None of them came with power cords.

Research let me to this forum but the connector wasn't easy to obtain. Another resource showed me that this is a min-xlr connector, a Switchcraft TA3 connector and the female version would be needed. Again, the connectors were $7+ a piece. Trimble themselves want to charge me $20 per cable. I love my group, but every penny counts.

I said screw it. I'll do what I've done before when companies don't make it easy. I decided to figure out the layout of the pins and simply remove the connectors. You can either put in your own connector or do what I did and hardired it with a pigtail.

NOTE: If you have some of these and want to get rid of them, my local ares/races group is looking for more.

DISCLAIMER: It's not my fault if you screw something up so don't blame me! I'm only sharing my experience. If you don't know what you are doing, seek the assistance of someone who does. If you are drunk, stoned, or just don't have steady hands, I don't recomend this.

Here's how to get it done:

1) remove the series of screws on the top of the GPS
2) remove the series of screws on the bottom of the GPS
3) remove the nuts and serial stands from the front of the unit. One nut and washer from the antenna connector, two stands per serial port (6 total in my unit), one nut from the power connector. The unit should seperate easily now.
4) remove the 4 screws holding the PCB to the bottom of the case.
5) pinch closed the tension fittings. They look like odd phillips screws with 4 quarters of a post. There is one on the upper left and mid right.
6a) remove the power connector. I broke both sides of the plastic holder. I then pulled the plug itself until it was verticle. I then snipped the 3 conductors and continued to remove the plastic holder.
6b) break out the soldering iron and remove the broken conductors from the 3 solder pands.

BEFORE I CONTINUE: The 3 pads on the PCB look like a triable. One on the top and two immediatly below it. The top pad is (positive) + and is the ignition sense. The bottom left pad is regular (positive) + power. The lower right pad is (negative) -. You need to combine the ignition sense AND postive in order to keep it fully on. You can use the ignition sense if you want to wire it into your car. It uses approx. 300mA, the manual on Trimble's website yields more information. Each hole in the PCB on the solder pads are rather small.. I went through 3 sizes of wire before I used some wires from a Cat5e Ethernet cable.

7) grab the soldering iron and solder the leads into the holes on the pads. Make sure not to bridge surface traces.
8a) secure your soldered leads. I used a combination of silicone and "welders" glue. I also soldered my leads to larger more flexible wires so I could secure the solder points and use more flexible wire for remote power.
8b) reassemble, apply 12v DC, and enjoy.

NOTE: You need to configure the gps to do NMEA output. It does not do this by default unless someone has configured the unit for you. As you may already know, this gps REQUIRES an external GPS antenna. They can be found for less than $20 on ebay. Please refer to the owner's manual. It's full of useful information.

73's KC9LFD - kc9lfd at kc9lfd dot org (yes, hard to remember I know... you may want to write it down and post it on the fridge
 
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