<p>Just last night the heat bed stopped working. It was fine up to 75&nbsp;% of the print, then when it was done the bed was not on anymore. The display said it was set to 50&nbsp;&deg;C, but it was at 18&nbsp;&deg;C. I did try moving the pins, and that is not loose (very simple thing to try). </p>

<p>I want to know what could have happened and what to look for when I try to fix the heat bed. </p>

<p>Please note: I do have a multi-meter. I do not use a MOSFET (I do have plans to install on)</p>

<p>Upon further investigation, I tested the mother board for any voltage were the bed hooks up and there is nothing. I had the printer trying to heat the bed when I was testing. But the thermistor is working, when I unhooked the connection the thermistor went to 0&nbsp;&deg;C, when plugged in it went to 18&nbsp;&deg;C. </p>

<p>Is it the motherboard? How can I fix this knowing no power is being supplied to the bed from the motherboard? Do I need a new motherboard?</p>

This is a shot in the dark, but the vast majority of problems with a heating bed stopping to work is usually at the cables/connectors interface.
This is because in printers like the A6, the cable/connector is subject to constant mechanical stress, and - since
metal fatigue
is a thing - either the solder or the cable core cracks.
You should make good use of your tester to verify the integrity of the circuit in the bed and if it is not toasted you should be able to just repair the connection.
For many printers there exist "strain relief mods" to prevent this type of failure to happen.  The first one showing up for the A6 is
a full chain
, but normally is enough the have a small enclosure for the connector like
this one
for the CR-10.