Datsun Roadster Forum-311s.org

Is it still normally working, or is there now 12 volt on the gauges.

Peter and Roman.

I tried the solder thing yesterday and despite my best efforts, it seems as though it sends a 12v to the output side. I tried soldering in different configurations as well. I also made sure everything that was supposed to be grounded was. I even placed the leads on the correct way, then the reverse way and still got 12V in and 12V out in both of those configurations.

that being said, my gauges WERE dead in the water, but the solder brought them to life. The problem is that instead of reading empty fuel and no temp, they spike to full fuel and top end of engine temp as well. I was excited to see it created a connection but I think for my particular unit it's just as ineffective.

Mike

Bummer. Well..... we tried. At this point I defer to experts.

Open it up and make sure that the points aren't fused

Ah....... That reminds me of my years old repair. Thanks for refreshing my memory, Sid. I did get some 600 grit and cleaned the contact points as well.

Mine were last week also corroded and works strange,(up and down), but I was driving in the rain at that moment, after a day he was working normally.

Ha! I just had mine fail on me too. Glad to see there are 1,000 other posts on the same topic. I soldered all the rivets, sandpapered the contact points, and I found that the ground connection was very unreliable.

Mainer311 wrote:Ha! I just had mine fail on me too. Glad to see there are 1,000 other posts on the same topic. I soldered all the rivets, sandpapered the contact points, and I found that the ground connection was very unreliable.

Did it work for you? (the fix) Or am I the only one who has had success with the repair?

Roman wrote:

Mainer311 wrote:Ha! I just had mine fail on me too. Glad to see there are 1,000 other posts on the same topic. I soldered all the rivets, sandpapered the contact points, and I found that the ground connection was very unreliable.

Did it work for you? (the fix) Or am I the only one who has had success with the repair?

Sure did! The coil wire wraps around that thru-hole in the PCB, and the little "c"-shaped clip that clips over the wire was tarnished all to hell. My meter wasn't reading any continuity, so I pinched the c-clip smaller, and sanded the entire thing to expose bare copper again. I then clipped it back over the wire. After I installed the board back into the metal case, I soldered the c-clip to the metal case to ensure there was a good ground connection there.

YAY!!!! Another success!!

I tried the electronic one with the LM7808 but when the engine is of it shows the good value and when the engine is running it shows to much on the fuel gauge.
What also strange is that I don't need the ground for working.

peter wrote:I tried the electronic one with the LM7808 but when the engine is of it shows the good value and when the engine is running it shows to much on the fuel gauge.
What also strange is that I don't need the ground for working.

Use a multimeter and see what voltage you're getting out of it. The 7808 won't actually work without a ground. Maybe there is a short somewhere? Are you using caps on the input and output to level out any fluctuations in voltage?

Pin 2 (middle) is the ground:
http://www.mouser.com/ds/2/149/fairchil ... 325814.pdf" onclick="window.open(this.href);return false;

I used a voltmeter and it is about 8 volt at the outside, without an with the ground.
I didn't look when I started the engine if the voltage was different, but that must be, otherwise it could not change.
I use also use the 0,33 and 0,1 caps on the in and output, the yellow wire is the plus, isn't it?
And the yellow/green the output.

The back case of the IC is actually a ground, so if the chip is touching metal, it will actually be grounded, w/o having the center pin grounded...so maybe it actually is, when you think it isn't? Just a thought, as I'm not sure.

The voltage out should always be 8 volts, despite what the voltage in is. That's the point of the regulator.

On '66, yellow is the input, and yellow/green is the 8V output.

Center pin needs to be grounded for reference of the chip. You get unstable voltage without it.