Model 932i. Why does it just display dots on the display board and won't do anything else?

http://www.precor.com/products/media/english/Treadmill_932i_Manual_Maintenance_Reference_Assembly_English.pdf

Hi Wimbledon.
see if this youtube helps you out.
Treadmill How to Check and Replace Control Board Fuse
or this link.
Precor 932i treadmill where is the fuse Google Search

If you wish to get some details a bout treadmill repair then check the link bellow.
http://electro-medical.blogspot.com/

HI There,

Did you get this worked out? Possibly the IFT drive?

Several things you can try here. If the stops switch is stuck it will cause the display to be blank. There also may be a loose connection to the upper or lower board. You can remove the front cover and check the connections to the lower board. The upper display connection will look like a cat 5 cable. Unplug it and plug it back in. That same cable runs up and plugs into the upper board. Check that connection as well. If those don't work then it may be the lower PCA.

Typically on the Precor Treadmills if there are errors on the unit, you can press and hold the stop button for 3-5 seconds and it will go into the error log. Not sure what model you have.
E-2 is not what normally shows up on the screen. Do you mean Error 2 was displayed? From what I have read on Error 2's it could be a upper PCA issue, or possibly a dip in AC input during the power up sequence.
Treadmills require a dedicated line, meaning it is on its own dedicated circuit on your fuse panel/circuit breaker.
What exactly is the treadmill doing? Is it constantly showing Error 2 on the screen? Call up Precor tech support. They will be able to give you advice, and or get you connected with an authorized Precor factory trained technician who will be able to get you back up and running.

Dear Sir:I am recommend you to exchange the board. If you do not have ENOUGH experience will be better to buy a new one, or call some tech profesional for to execute this delicate work.
The causes can be various, Maybe you have SHORT circuit in the motors, power supply, see the block diagram.
God bless you

Unplug your printer from the outlet for several minutes and repower it back up. I have had this with my printer and usually solves the problem.

Hello:
This may be due to a faulty T-Con board that needs replacing, this board is the display driver and will cause all type of symptoms when it is going bad.

What year & model? Are you describing On Board Computer display?