Combination Meter, 521

[DanielC]

This is a combination meter out of a 521 I recently bought. It needed some repairs. None of the lights worked. The wire jumper was on the circuit board already, I did not do that.

And this is a high res picture of the same thing.

 

To start with, you need to know what all the pins connect to.

 

To test the meter, you will need a source of 12 volt power, and three wires to hook up to the meter.

 

Some of the lights on the meter light up when power is put on their pin, and the meter grounds the lights. Pin #1, four meter lights. Pin #2, left turn. Pin #9, high beam indicator, Pin #12, Right turn.

Connect pin #10 to negative battery power, and connect pin 1, 2, 9, and 12 to positive battery and the light should light up.

 

The OIL and IGN light are supplied power by the combination meter, and come on when their pin is grounded. Connect positive battery power to pin 7. Connect pin #4 to negative battery, the OIL light should come on. Connect pin #8 to negative battery, the IGN light should come on.

 

To test the fuel gauge, and the temp gauge, do this. Connect positive battery power to pin 7. Connect pin #10 to negative battery power. This powers the meter. Connect a third wire to pin #3, and then connect that wire to negative battery power. The fuel gauge should go all the way to full. Connect a third wire to pin #11, and then connect that wire to negative battery power. The temp gauge should go all the way to full.

 

I started off by checking the four meter lights. On my meter, the bulb holders are black. The power for the meter lights goes clockwise around the circuit board. I had to clean the corrosion off the board, where the bulb holder makes contact. In this picture, I have cleaned one half of the connections.

I also has to clean the bulb holder contacts, both in the socket that contact the bulb, and where the bulb holder contacts the circuit board.

 

The grounds for the circuitry are not really on the circuit board. The ground connection is made by the metal case of the meter, and the rivets holding the circuit board. I found two places where the rivet was not making contact with the circuit board. To fix that, I cleaned the top of the rivet, and the circuit trace next to the rivet, and soldered over the two, like this.

I also had to do the same thing on the rivet by pin #10.

After doing these repairs, I redid the checked the meter using the above repairs.

 

I probably should tell you how to get the combo meter out of the truck. Remove two screws at the bottom of the black plastic cover, and then slide the plastic cover straight down. The top is held by two spring clips.

Remove the speedometer cable by unscrewing the cap aht the end of the cable, and then carefully unplug the multipin connector.

The top two screws have nuts on the back of them. Remove the screws, and the combo meter is free of the dashboard.

[Pacific coast Datsun]

Great writeup. I wonder how close the 521 cluster is to one out of a 74 620. I had mine apart a few weeks back to try & remedy non working dash lights & gas gauge.

[sick620]

my fuel gauge and temp gauge dont work they just go crazy all the time... do I need a new voltage regulator on circuit board or is there a way to repair old one?

[thisismatt]

Nice work. To get a good solder joint, be sure to remove the green resin on the trace you plan to solder, and use a good flux smeared on the trace, not just flux core solder alone.

 

Anybody remember the "pencil trick" for unlocking AMD cpus? Pfft, pencil...

[DanielC]

I do not know if they are repairable or not. It looks like there is one screw that holds it on the circuit board, and it unplugs. I understand it is just a small heating element, and a thermostat that clicks on and off to regulate the voltage, and it has a set of points that could be cleaned.