RAMBo <1 vdc Fan Voltage?

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

Edited 1 time(s). Last edit at 08/09/2013 02:17PM by Filip.

While trying to switch extruder fan control from Fan0 to Fan1, I stumbled on this thread:
[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.

Edited 1 time(s). Last edit at 08/09/2013 03:36PM by Filip.

Update since I can't edit my post anymore:

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]

Edited 1 time(s). Last edit at 08/12/2013 08:09PM by Filip.