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Bad gauge cluster voltage regulator? Easy $2 fix.

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Problem

 

You're temp/fuel gauges don't work and you've already checked the output from your fuel/temp sensors to make sure they are not the culprit. You checked continuity of the wires from the sensor to the gauge and the output from the current voltage regulator to find out that it outputs the wrong voltage, none at all or it's fluctuating. Well guess what, I have a solution for you!

 

I recently found out that my gauge cluster didn't have a voltage regulator, which is why my fuel/temp gauges don't work. Well that's totally unacceptable for me because i want to run all the stock gauges in my 510. It would bum me out to have to run aftermarket gauges when I have perfectly good gauges already in the cluster.

 

Fast forward to a few posts and questions later I learned the following.

 

Some basic info needed to figure out the problem

  • The gauge cluster needs ~ 9v to power the fuel and temp gauges
  • The car is DC and runs off 12-15v (i'm only putting this for people who may not know)
  • Without a voltage regulator, the gauges do nothing

How the sensors work with the gauge cluster

 

The gauges always have power. As temperature or fuel level rises/lowers the resistance in the sensor changes. It allows more or less current to pass through it to the chassis ground. Both sensors work in the same way.

 

So the problem is we just have the wrong positive voltage going to the gauges... Well all the voltage regulator does is keep the voltage constant given any input power. OK... What are some options? I personally didn't want to buy a whole gauge cluster just for the voltage regulator. I have a background in basic electronics and arduino stuff, so I started searching mouser electronics, digikey and my local parts place marvac.

 

I found out something awesome.

 

There are a million really cheap tiny voltage regulators that do the same job as the big metal one on the back of the gauge cluster. Average cost? ~$0.43 to $2.00.

 

Well that's bad ass isn't it?

 

I picked up two just to be on the safe side and a PCB (printed circuit board) and set to working.

 

Parts

 

  • Voltage regulator
    • NTE1910 or
    • LM7809
  • Wire (preferable 3 colors)
  • PCB board (optional but makes it nicer)
  • Project box (optional but makes it nicer)

 

Explanation of pins on the voltage regulator

 

LM7809CT.jpg

 

Here's a picture of the voltage regulator for reference.

  • Pin on the far left is the power input (in our case 12-15v)
  • The center pin is a "common ground". Just connect it to your chassis ground
  • The far right is the power output (9v)

There are some upgrades you could do to stabilize the signal by adding capacitors, but i honestly didn't think it was a big deal. this isn't the biggest deal in the world, it's a gauge.

 

Tools needed

 

  • Soldering iron
  • Solder
  • Multimeter (handy but not necessary i guess)
  • Third hand tool
  • Dikes to cut the wire
  • Wire strippers
  • Electrical tape
  • Black wire*
  • Red wire*
  • Another color of wire*
  • Project box (optional)

*Solid core wire would be best in my opinion for this project since it is not designed to be moved around a lot. Additionally, pick a wire gauge that will fit through the holes in the PCB.*

 

Setting up the voltage regulator on the PCB

 

If you're not good at soldering tiny wires, pick a PCB with larger spaces between each hole or spread the pins, being careful not to break them so you have a hole in between each pin. That should be plenty of room to solder comfortably.

 

  1. Place the voltage regulator on the PCB, bend it so it lays flat against the PCB and solder all three pins.
  2. Place the red wire in the hole in front of the power input pin (far left) and solder it.
  3. Place the black wire in the common ground pin (center) and solder it.
  4. Place the 3rd color wire in the voltage output pin (far right) and solder it.
  5. Connect the power and ground pins
  6. Test the output power pin with a multimeter to confirm ~9v.
  7. Hook up output power to your gauges.
  8. Have a beer.

That's it. Easy right?

 

Finishing touches / final thoughts

 

  • Placing this into a project box would be a good idea to keep wires from being broken/bent
  • If you cut down a PCB to a smaller size, sanding the edges will make it look nicer
    • Score both sides of the PCB with an exacto and you will be able to snap it like a cracker

 

Pictures!

 

Checked the battery for static test

541624_10200437490571408_440936923_n.jpg

 

Third hand tool is nice for soldering PCBs with tiny holes.

3668_10200437490411404_1314807326_n.jpg

 

This is an idea of how small the VR is compared to the old school one.

538033_10200437531452430_430586_n.jpg

 

Didn't want to fry my gauges so I checked the output before hooking anything up

532288_10200437490531407_1833411342_n.jp

 

Testing my gauge... SUCCESS!!!!

537055_10200437490491406_1178148889_n.jp

 

So tiny :) I'm so glad I can now finish putting together my gauge cluster. 

11499_10200437490451405_847269814_n.jpg

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Now that is awesome. Good job dude

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I wish I would have known this was a needed guide... I would have written this awhile ago. I used to to tons of PCB work for the Navy. This is a well written guide and I hope it comes in handy for everyone. 

 

I would recommend pm'ing a mod and ask to move this to the how-to section add to the collection of good articles in there. 

 

 

 

Great work! :thumbup:

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Part #s and where you got them? Also, do you have any pics of the finished solder job, with wires attached? Thanks for the write up B)

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this is now a stickie in how to

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Unfortunately this was all an after thought and I only used red and black, but when I get home from work I can take some more pictures and maybe throw it on a breadboard to make it easier to see

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OMFG

My Fuel Gauge Has Been Tweaking Forever

Will Make A Run To Radio Shack Very Soon!

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OMFG

My Fuel Gauge Has Been Tweaking Forever

Will Make A Run To Radio Shack Very Soon!

check connections to fuel tank..mine was reading okay one and then next day was not reading good. 

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part number is on the voltage regulator and failry sure monkey shack sells these or any other electronic hobby store.

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Stabilizing capacitors would not be necessary.  The panel meters are basically bimetal strips which bend as they are heated up and are hooked to the needle and inherently average out any voltage fluctuations, or more properly current fluctuations due to "DC" waveform in the original voltage rectifier which produced an almost square wave output as "regulated" voltage. [Run on sentence but you get the drift.]

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Thanks MikeRL411, I had read about how the strips expand/contract at different rates to cause the deformation, but didn't think about the response time. You're right, capacitors aren't necessary :)

 

There are a lot of different VR's that will do the same thing.

 

NTE1910 is the equivalent of LM7809. I happened to have used the NTE part because the LM one was not available for pick up in store. Radioshack likely won't have these in stock at their store, but any electronics component store should. 

 

Edit: I updated the original post with part #s

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Doing that today, as I'm working from home. I'll take a few pictures. I didn't use a box or anything, mainly because I don't care... i just want working gauges. Give me an hour or so :)

 

Also, if anyone was wondering, that power input for the instrument cluster is a small hole on the back of the temp gauge for 69 510s. It took me a very long time to figure that out.

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OK, i don't have electrical tape or a box or anything. Normally I wouldn't post this because it looks terrible, but just so you can see how small, etc here's a pic. I can't go get tape or anything because my civic is in the shop and both of our other cars are not drivable ATM. No flame please :)

 

253211_10200609530032287_1990042034_n.jp

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OK I see your fix.

 

kinda got 2 threads goin on this but.

 

You said both gauges didnt work. So you use 2 volt regs? 1 for fuel and 1 for the Fuel?

or can you put the VR in the middle and slice them to both sides like the stock set up. Just solder the 9 volt wire to the trace where the old one went to.?

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This also took me forever to figure out. See where the red wire goes into the back of the (fuel) gauge? There is a connection that runs from there all the way to the other gauge powering it as well.  It continues through that gauge to the other side of the the cluster powering some lights and things. So far it looks like this is the power for both gauges and the warning lights (oil/charge). I didn't trace it beyond that yet. I believe all the warning lights are powered on this circuit and the dash lights are 12v. Not 100% on that though. I will update this and my build thread as I find things out though. I suggest printing this epic picture out at kinkos or somewhere on a very large piece of paper. It's SOOOOO helpful. Wire colors are incorrect for the 69, however, so match pin #s, not colors.

 

datsun_510_wiring_diagram.png

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On a 521, when the combo meter get ignition power, it applied 12 volts to the oil light, and the (IGN) light, ans well as supplying power to the gauge voltage regulator.

 

If the engine is not running, the oil pressure switch grounds the oil light, it comes on.  The alternator also grounds the (IGN) light, and it comes on.

 

Grounding the sender wire for either the fuel gauge, or the temp gauge, causes the respective meter to read full. 

 

I believe a 510 acts similar to this.

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May I suggest buying a simple buck converter instead of making one?  They are pretty dang cheap and already professionally built, so they'd install clean.  There are some cool ones available, even some with LED voltage displays that will tell you the input & output voltages.  They are a switched mode power supply and they don't generate a lot of heat like a linear regulator, so less heat and high efficiency.  I don't know what the current draw is on the gauges, but probably not above 3A, so these should work fine.  These could also be used to drive LEDs for guages/clusters and one could offset the potentiometer to create a dimmer circuit.

 

Here are some examples on amazon:

 

http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=LM2596

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Been playing with this a bit. This should be a direct plug in.  Screw hole is ground, red is 12v+ blue is 9v+.

EC4ADCB3-9008-45F4-89D4-A2048C8A9DC5-333

 

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