Hi All, The RAMBo board on my MendelMax 2.0 kit suddely lost voltage on the Fan0 connection. The stock fan failed (would start/stop randomly, despite a constant 24vdc source). So I cut the leads to the old fan, soldered on a 3 pin molex connection, then plugged the new fan in. After powering the printer and sending a M106 S127 command (it's a 12vdc fan) it spun up. Then I sent it M106 S50, and the fan reacted accordingly. Then all of a sudden it stopped. Now the fan lead (and output on the board) read .762 volts at S255 and .882 volts at S127, both without the fan connected (no load). If I send S0, volateg drops to ~55mv. Did I do something to damage the board, or is there some setting / reset I don't know about? I turned off power to the printer PSU, disconnected the connection, and restarted both the board and printer PSU and re-connected Pronterface and got the same results. Both thermistors read the proper temperature, and all 4 steppers function as expected. Thanks in Advance, -Filip https://reprap.org/forum/read.php?4,234208,234208#msg-234208 Sun, 15 Mar 2026 13:58:13 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,234208,235201#msg-235201 https://reprap.org/forum/read.php?4,234208,235201#msg-235201
The link above to Digikey orders the wrong part (it was the surface mount version - about 10 times smaller than needed). This one from Newark should work:
[mail.google.com]]]> Filip Reprappers Mon, 12 Aug 2013 20:08:59 -0400 https://reprap.org/forum/read.php?4,234208,234219#msg-234219 https://reprap.org/forum/read.php?4,234208,234219#msg-234219 [groups.google.com]

Following that advice, I found that one of the 5amp Littelfuse 435005s, above the Ext 2 connector, burned out. I replaced it with the one below (from the Thermistor side) and the fan worked again.

I ordered a few replacements from DigiKey:
[www.digikey.com]

Also, I used Anthony's (in the thread above) idea and made a temproray 5amp ATM to SMD fuse per the attached, to keep me going.

I wanted to close this out in case anyone else has the same issue.]]> Filip Reprappers Fri, 09 Aug 2013 15:08:49 -0400 https://reprap.org/forum/read.php?4,234208,234208#msg-234208 https://reprap.org/forum/read.php?4,234208,234208#msg-234208
The RAMBo board on my MendelMax 2.0 kit suddely lost voltage on the Fan0 connection.

The stock fan failed (would start/stop randomly, despite a constant 24vdc source). So I cut the leads to the old fan, soldered on a 3 pin molex connection, then plugged the new fan in. After powering the printer and sending a M106 S127 command (it's a 12vdc fan) it spun up. Then I sent it M106 S50, and the fan reacted accordingly. Then all of a sudden it stopped. Now the fan lead (and output on the board) read .762 volts at S255 and .882 volts at S127, both without the fan connected (no load). If I send S0, volateg drops to ~55mv.

Did I do something to damage the board, or is there some setting / reset I don't know about?

I turned off power to the printer PSU, disconnected the connection, and restarted both the board and printer PSU and re-connected Pronterface and got the same results. Both thermistors read the proper temperature, and all 4 steppers function as expected.

Thanks in Advance,
-Filip]]> Filip Reprappers Fri, 09 Aug 2013 14:03:55 -0400