'95 Maxima Gauge Retrofit

[zbigtim]

Well, I finally got all the stuff together to make a circuit board. I decided to chemical etch the board instead of photo-etch. The photo-etch process seemed to be more complicated, but I understand is better suited if I wanted to mass produce the board. The board is small enough, I'm thinking of mounting it to the back of the speedometer.

 

I was able to mask the copper layer by transferring a laser printed pattern on glossy photo paper with a hot clothes iron. This picture shows the board after the transfer.

 

After an acid bath, the copper that was left exposed is etched away.

 

After cleaning the mask and soldering the components on the board. I had a little bit of trouble on the soldering because the tip of my soldering iron was too blunt, and the solder could have been thinner. Any extra solder or mis-placement of the iron allowed the ground plane to soak up excess solder. But the solder still did not bridge any of the traces. Whew!

 

This is the top view after the board was completed and tested. Ready for installing in the car and final calibration done with a road test and my GPS.

[zbigtim]

Did I lose everybody on this mod? Does the extra circuitry make this mod not worth the trouble?

[Six_Shooter]

Most people are scared of building electronics like this, so this will probably not be done very much.

 

Building my own etched circuit boards is something I need to get familiar with. Usually I just use the point to point generic boards.

[zbigtim]

Most people are scared of building electronics like this, so this will probably not be done very much.

 

Building my own etched circuit boards is something I need to get familiar with. Usually I just use the point to point generic boards.

 

 

I would agree. I've tinkered with electronics, seems like my whole life, and have always used the proto boards. This was my first attempt at etching my own board, and found it relatively easy. There is tons of info on the web on this topic.

 

I'm pressing on with the mod. I think all the difficult parts have been solved. The next step will be the tach, and I think that is going to be much more straight forward.

 

I think may get more enjoyment out of the problem solving than the actual finished product.

 

-Tim

[Xnke]

I get the same kinda feelin' sometimes, Tim. I'm also doing the maxima gauges, but will be using EL wire to do the backlighting.

[Xnke]

Doing a little research on this, it seems that the Maxima and the 240SX BOTH have a year split at 1994. It is fairly common to have an S13 SR20 swap go into an S14 USDM chassis.

 

When the speed sensor is adapted over but the speedometer is not...the speedo reads twice as fast. Just like the S13 speed sensor and the 95+ maxima speedometer...I'd wager that the speed sensor for an S14 would work just fine with the 95+ maxima speedo. I have an S13 speedo sensor, but I'll see if I can aquire an S14 sensor and test it out. If it works, then this could be a very easy way to get both a stronger transmission, plus an accurate speedometer!

[Xnke]

Bringing this back from the dead. I have gone through this thread a large number of times, and am working through figuring out the schematic and the PCB layout, which do not match each other. (Close, but there are parts on the board that are not in any of the schematics, and parts in the schematics that are not on the board)

 

I do have the speedo working on the bench, though. The tach is quite straightforward, the Megasquirt Tacho Output circuit works like a charm.

 

The speedometer doesn't care if it's a sine wave, or a square wave, as long as it's a bipolar signal. It only need about a 3V output to work, but that 3 volts MUST cross zero volts, so it's more like a minimum of +/- 1.5V. I solved this by referencing ground in an odd manner and that solved the issues with the speedo acting funny at low speeds.

 

EDIT:

 

I've figured out the "floats at low speeds problem, too...The differentiator capacitor was too small, and so the speedo would cut out at high speeds and would float at low speeds/nearly stopped/stopped. Upping it from 0.1uf to 0.22uf fixed both problems nicely.

Edited March 3, 2013 by Xnke

[Xnke]

Here's some shots of how I did the gauge cups for this conversion. After making those few tweaks to the speedo drive circuit, this was the next challenge.

Getting started. Heat up some 4.5" PVC pipe and shove a quart paint can inside it. Dunk in water, and beat the paint can back out of it.



Turn it down to fit in the bezel:



Fits!



I hole-sawed the back of the Maxima cluster out around the speedo and tach mounting points, leaving me with a circle-ish chunk with the mounting points intact. This leaves me with a nice backing plate to use. The backing plate was then mounted to the gauge, and the whole assembly fitted into the bezel. Then the backing plate was then taped up with aluminum foil tape, used for ductwork, because it's stiff enough to hold it in place during handling, like so:



Now, the gauge is removed from the backing plate, and we have a nice little channel to fill full of JB weld to permanently secure the backing plate.



Like this:



After letting it harden up for a few hours, this is the result:



The bezel fits perfectly over the gauge, but the bezel needs to be sanded and painted, since the little lip inside had to be filed out to allow the shine-through type backlit face to fit correctly...the original gauges are opaque and the light wraps around a gap around the edge of the face.

Still working on getting the gauges lit correctly.

[zbigtim]

Nice work Xnke!  Wish I had access to a lathe and the skills to use it.

 

Hey, You say you had no trouble getting the tach to work with the MS Tach Out.  Iv'e got my tach mocked up on the bench, but cannot get the tach to span higher than about 3750rpm without the pointer getting erratic.  I'm just using a square wave generator right now, found the scale to be about 1000 rpm for every 50Hz, using a 50% duty cycle.  I wonder if I just have a bad tach.

 

Using the circuit in the MS Extra Hardware Manual

 

http://www.msextra.com/doc/ms1extra/MS_Extra_Hardware_Manual.htm#tachoout

 

-Tim

Edited March 25, 2013 by zbigtim

[Xnke]

Tach needs a 0-12V pulse, the offset needs to be correct, and 0-5V won't do it. Gotta make sure that there is a common ground reference too, or it'll do that.

[Xnke]

More info on the tach:

The tach circuit from the MS manual is correct, and works perfectly with my 95 maxima speedometer. I used a 1k resistor from +12v to the collector of the transistor, 1k resistor from the base of the transistor to JS2 on the megasquirt v3.0 board, and I used an NTE123AP transistor...basically a hotted up version of the old 2N2222A that is recommended in the manual. I had one handy, so I used it. The standard 2N2222A should do the job just fine.

Edited March 27, 2013 by Xnke

[zbigtim]

Yea, that's what I'm afraid of.  I used a 2N3904 with the same values on the resistors and the results are as previously posted.  Oddly enough, I don't have any 2N2222s lying around.  I used another transistor out of my "NPN" drawer with the same results.  I don't remember what the P/N was.  Hopefully the issue is with my square wave generator.

 

-Tim

[Xnke]

Yep, I used an MPSA42 the first time, gain was only 40-70 and it would read up to about 1800RPM and it was done.

[winstonusmc]

Bringing this thread up again. I decided to go with this setup due to my coil on plug design from Megasquirt not working with my factory tach. I also want the speed sensor input on the MS3 so it can calculate HP and MPG.

The cluster is from a 95 era Maxima
Transmission is later 280zx
Speed sensor is from an R33 NA Skyline w/ red gear
Tach is connected to MS3X Tach out

Its all mocked up on my front seat now and both speedo and tach work. Tach is accurate and speedo is of by 81%, which is from the red gear is for 4.11 gears and the Z is 3.36. Need to get a yellow gear for the sensor now. I need to sort the output of the speedo to the VSS input of the MS3, couldn't get it to work on a Nissan before using the speed input on the ECU, but that was a while ago.

 

http://youtu.be/jbHLYRAht4I

Edited January 9, 2014 by winstonusmc

[winstonusmc]

There are currently 4 indicators that are in the tach and speedo gauges. The two turn signals are in the tach and the bright and brake malfunction lights are in the speedo. Don't really care about the brake malfunction light, so here is the solution, I presume these used to be something with the A/T or suspension modes. They were blank on this cluster. Had to open the holes up and super glue the other indicators.

 

[winstonusmc]

Update, the correct speedo gear is not available for the 3.36 gears. Matter of fact, the only one that is available is the red gear. So I guess I need the 4.11 gears from the S12 200sx

[winstonusmc]

 

 

Used LEDs for the back lighting. The gauges are mounted on plastic electrical box covers from Home Depot and glued to the origional gauge cups trimmed to fit.

Edited January 15, 2014 by winstonusmc

[winstonusmc]

Gauge install is done. Well, still have to put the new sensor in the transmission and run the wires. Here is a video of the function of the tach, it has the indicators on it. Yes, as some have pointed out, the speedo is crooked, but it can be adjusted. I was also able to find a better speed sensor with a closer gear, a Q45. It had the black gear on it and uses the same sensor as the S14/R33 sensor. My calculations is that the speedo will be 4% off.

 

 

http://www.youtube.com/watch?v=u66DyhLGY3w

Edited January 25, 2014 by winstonusmc

[winstonusmc]

Hooked up the speedo sensor today. I used exsisting wiring. Not really sure where or what the wires were supposed to go to, but it was two green wires hanging near the speed sensor. I just cut the plug under the dash for those green wires and spliced it into my guage harnes that I fabbed up. Now the speedo works pefectly. The error is about 2% with the stock gears and the black 17 tooth speedo gear. I really like how solid the speedo needle is. The only thing is there is no way to reset the trip, thinking about the 98-99 speedos as they are digital trip/odometer. Then I can just put a button somewhere.

[Xnke]

Awesome! The Black cog would be spot on for a 3.54 rear gear set, so that's great.