# Reading Relay Pin Diagram (TQ2-12V)

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#### dfidler

Hi All,

I'm looking at a PCB that has three relays marked TQ2-12V ATQ203 and I'm hoping that you guys can sanity check my questions/assumptions based on the datasheet and the readings I'm getting.

This image is from the Panasonic EW TQ2-12V datasheet (http://www.farnell.com/datasheets/22540.pdf):

Questions:

1. I'm not sure if each diagram represents a different part or different states of the same part based on how you hook it up?

From what i can tell from other datasheets, they do refer to different parts.

2. What is the significance of the color of the coil in the diagrams?

I have two theories on this.

The first is that the color of the signal pins (highlighted in yellow in the picture) represents the latch position for the latching relays. White means means that pins 2/3, 9/8 are closed and 4/3, 7/8 are open while black means that state is reversed.

The other theory is that they represent the polarity of the signal that should go through the pins and that there is a diode or resistor in place to prevent reverse voltage spikes.

3. Which pins are the power in and NC?

If I'm reading this right, pins 3/8 are ouptut, 2/9 are the NC input and 4/7 are the NO input. I'm not sure what the significance of the black dots for pins 2/9 are for though.

4. Which one do I have?

In my circuit, pins 5/6 are going to ground, which doesn't tell me much. Measuring the R between pins 1/10 gives me about 1K so I'm guessing that, if the diagrams represent different parts, I have a single side stable or 1-coil latching (this is further supported by the fact that pins 1/5 and 6/10 show no resistance/connectivity at all).

Other than powering up the board and/or desoldering the relay (which I don't want to do for fear of disturbing the IC that's adjacent to it) and powering the relay directly, is there a way of determining whether this is a stable or latching relay?

Or will I just have to guess based on the circuit that it's servicing?

Note: I haven't yet mapped out all of the pins between the various releays as this is a multi-layer PCB and it's taking some time to figure out what is connected to what. Therefore, I don't totally understand the purpose of this circuit yet, though it seems pretty likely that it's part of the amp's input circuit protection (which would make me want to say it's a latching relay).

Cheers,
Dave.

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#### PedroDaGr8

OK it appears from what I can see of the datasheet the technical name would be

TQ2-Nil-Nil-12V
Nil of course means nothing (so they shorten the name to TQ2-12V)
So it would be appear that you have:
Single side stable AND Std. B.M.M Type (no clue whatthis means).

#### PedroDaGr8

Ahhh MBB = Make Before Break. Had not encountered that concept before (I am used to automotive relays which I guess are Break before make).

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