<p>I recently rebuilt my A8 printer to have a metal frame and replaced the board with a GT2560 reva+. I'm having problems with the temp readings from both my hotend and hotbed. Using marlin 1.1x and Its possible I have something configured incorrectly. I can get successful prints with good quality but sometimes I get thermal runaway during a print.</p>

<p>Both cold and at temp (200c) have fairly large temp spikes. I didn't have this problem with my old board. I had much smoother temp curves. I'm using the default PID values for Ultimaker Kp 22.2, Ki 1.08, Kd 144.</p>

<p>I have tried to use PID autotune but get drastically different values every time I run it and using the results gave worse results (sometimes giving a heating error during the autotune). I checked all the wiring and nothing looks frayed or damaged. </p>

<p>First pic is cold temps. Second is trying to do a PID tune. Third and fourth are during a print.</p>

<p><a href="https://i.stack.imgur.com/7H8KC.png" rel="noreferrer"><img src="https://i.stack.imgur.com/7H8KC.png" alt="Temps cold"></a></p>

<p><a href="https://i.stack.imgur.com/EpW8E.png" rel="noreferrer"><img src="https://i.stack.imgur.com/EpW8E.png" alt="PID tune"></a></p>

<p><a href="https://i.stack.imgur.com/A9bU0.png" rel="noreferrer"><img src="https://i.stack.imgur.com/A9bU0.png" alt="During a print"></a></p>

<p><a href="https://i.stack.imgur.com/GwyP4.png" rel="noreferrer"><img src="https://i.stack.imgur.com/GwyP4.png" alt="During a print 2"></a></p>

[{'answer_id': 5491, 'author': 'Coder_fox', 'author_id': 9771, 'author_profile': 'https://3dprinting.stackexchange.com/users/9771', 'pm_score': 3, 'selected': True, 'text': "<p>I had a similar problem and there could be three reasons(if the connections are ok):</p>\n\n<ul>\n<li>thin wires to the hotend</li>\n<li>one of the MOSFETs was fried </li>\n<li>the termal sensor wasn't good enough insert into the hotend</li>\n</ul>\n\n<p>Try to measure the hotend heating element voltage while printing.</p>\n"}, {'answer_id': 5498, 'author': 'Valmond', 'author_id': 8328, 'author_profile': 'https://3dprinting.stackexchange.com/users/8328', 'pm_score': 1, 'selected': False, 'text': "<p>This really looks like a bad connection, so try with your old board to see if the broken connection is on the board, or it's the temp sensor or the wires.</p>\n\n<p>I had exactly this problem with a bad connection from the temp sensor.</p>\n\n<p>If you didn't break anything, it's the board that's fried / badly connected.</p>\n"}]
['https://3dprinting.stackexchange.com/questions/5490', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/9938/']