Putting voltmeter into L300 dash pod

[Erebus]

My inclinometer died, so I pondered what to do with the space. Since the Delica just begs for a voltmeter, especially given the events I do where draining the battery is an issue, I figured I'd put a voltmeter in the empty space. Then I had to decide between a analogue GM one, or a digital Colluck one I had. I picked the digital. (I had both laying around in my pile of miscellaneous parts.)

The Colluck PM128E digital panel display can be set up as an AC or DC voltmeter or ammeter, and variable range. The DC voltmeter configuration can be 0-200mV all the way to 0-500V; I picked the 0 to 20 VDC range with 2 decimal places as the most useful. The only drag is that it needs 5 VDC (or 9 VDC) to run, so I had to add a 3-tab regulator.

1) First thing I had to do was cover the angle markings on the front of the pod. I used the black vinyl cover off a 3-ring binder, cut it slightly larger than the circular opening, cut the opening for the voltmeter, then slipped in between the pod and faceplate of the inclinometer.

Pod face with vinyl insert to cover inclinometer markings.

1 pod faceplate.JPG (166.89 KiB) Viewed 5428 times

2) I added the 5V 3-tab regulator to the voltmeter's circuit board. I used a pin connector from computer parts, which just happen to slide perfectly over the pins, so that it can be easily disassembled. A 3-tab regulator (about 75 cents at electronics supply stores) takes 10-35 volts as input and outputs a stable 5 volts DC, which the voltmeter needs. Not my most perfect wiring and soldering job, but no one will ever see it -- oops except everyone on the forum!

3-tab regulator connected to the panel display

2 voltage regulator.JPG (170.5 KiB) Viewed 5428 times

3) Next I needed vehicle voltage. I posted a question a week or two ago about the wiring of the pod, but no one knew what wires do what. Since the thermometer and the dash lighting get power, I looked for the accessory-live connections. I took voltmeter to the dash side of the connector and found some pins that showed 12 V on accessory. But various combinations were possible so I partially disassembled the thermometer module, and had a closer look.

Delica's thermometer module, partially disassembled.

3 thermometer.JPG (161.28 KiB) Viewed 5428 times

4) A closer look at the circuit board of the Delica's thermometer revealed some very useful markings.

Delica's thermometer circuit board, with labels

4 therm board.JPG (170.92 KiB) Viewed 5428 times

Note the left-most wire (blue) is marked IG (which I take to be "ignition"), and the connection beside it (black/green wire) is labeled G (which I take to be ground). This matches one of the combinations I found to show voltage on the connector. When looking into the connector coming out of the dash, the bottom left pin is what goes to IG and the one beside it goes to the G on the board. I figure the IG should really be ACC, since it has power on accessory, not just on ignition. And that suited my needs perfectly.

5 & 6) Turning the board over reveals the solder pads that obviously didn't have the flux removed at the factory.

Delica's thermometer circuit board, the other side

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I then soldered the two sense wires for the voltmeter onto the appropriate pads.

Delica's thermometer circuit board, the other side, with voltmeter's sense wires attached.

6 therm soldered.JPG (167.62 KiB) Viewed 5428 times

7) The other end of the two wires I soldered on to the circuit board are soldered onto the 3-tab regulator. I then reassembled the thermometer. A 3-tab regulator should have a heat sink. Fortunately, the Delica has a thin sheet of aluminum in the pod behind the inclinometer that makes a perfect place to mount the regulator, and provide a heat sink at the same time. Bonus!

Delica's thermometer reinstalled, with 3-tab regulator.

7 therm installed.JPG (165.6 KiB) Viewed 5428 times

[Continued in next post, due to the forum's limit of 7 attachments per post]

[Erebus]

Voltmeter part 2

8) the voltmeter plugged into the 3-tab regulator. Here you can see what the front of the voltmeter looks like.

The thermometer reinstalled, with the voltmeter plugged into the 3-tab regulator.

8 wired.JPG (164.51 KiB) Viewed 5422 times

9) I then unplugged the voltmeter (there was a reason for using a connector!) and siliconed it onto the back of the faceplate. You can clearly see the yellow and grey face of the inclinometer pod that is covered on the front by the vinyl that you saw in the first photo.

The voltmeter siliconed onto the back of the front of the pod.

9 back of volt installed.JPG (156.73 KiB) Viewed 5422 times

10) and everything put back together and working. Yes, the altimeter is correct, Calgary is indeed at 1100 meters.

And the completed installation.

10 finished.JPG (166.92 KiB) Viewed 5422 times

Because the inclinometer is gone, the front and the back of the pod only use a couple of screws to hold the parts together.

The only problem with this setup is that because the LCD isn't backlight, you can't see it at night. Because the voltmeter is right against the old faceplate, the existing backlighting doesn't illuminate the front of the voltmeter. I might open it up and mount the voltmeter with some spacers hoping that some light will spill. The other alternative would be to have used a PM129B meter, which has the same functions but uses an LED display.

What I have since found out is that those meters are much harder to find than I thought. None of the electronics shops in town carry them, and even Ebay isn't very useful.

The other thing I realized after seeing what I've written is how much I learned in 2 years of school (I'm now an avionics technician). What I now blithefully write as "do this" then "disassemble" this because I think it is easy, I wouldn't really have understood 3 years ago. Guess an old dog CAN learn new tricks

For those without the electronics nerves, it could be done much more simply. If you use a standard automotive voltmeter, you wouldn't need the 3-tab regulator, and you would only have to connect the two wires to the same pads on the thermometer that I used for the sense circuit.

[Artacoma]

Nicely done!

[Erebus]

Thanks. The cool thing is that it is entirely reversible. If I decide to put another inclinometer in, I just have to undo some silicone and snip some wires.

[TardisDeli]

Hey Erebus, huge hugs from the Tardis Folk, we missed seeing you this year. Wow, time flies. You've finished your avionics tech course, congrats! Now we know who to contact for wierd electrickery that even Jay can't solve. cheers, Christine.

[Erebus]

Hey Erebus, huge hugs from the Tardis Folk, we missed seeing you this year. Wow, time flies. You've finished your avionics tech course, congrats! Now we know who to contact for wierd electrickery that even Jay can't solve. cheers, Christine.

Hugs right back atcha, we've missed you guys too. It has been more like 2 years since we were there last, way too long

I love the term electrickery, I might just have to steal that.

[yojimbo]

A word of caution, a lot of devices in those packages have + on the heatsink tab, in this instance it's fine obviously, and this package may be different, but bolting a lot of them directly to the car steel would let the magic smoke out quite fast!

Nice work, though I am rather fond of the somewhat pointless inclinometer!

[Erebus]

A word of caution, a lot of devices in those packages have + on the heatsink tab, in this instance it's fine obviously, and this package may be different, but bolting a lot of them directly to the car steel would let the magic smoke out quite fast!

Nice work, though I am rather fond of the somewhat pointless inclinometer!

I loved my inclinometer, spent quite a bit of time last year sealing it and refilling it with compass fluid, but it suddenly jumped its bearings and hung at 45 degrees, so time to move on.

Thanks for the warning, this 3-tab the mounting was definitely negative. Also, that little metal plate I used as heat sink is attached only to the plastic of the pod, so it isn't grounded in any way other than through the wires.