No power

RadioActiveLamb · September 25, 2020, 3:46am

I got the whole thing built, and am at the point where I am wiring the power with the Rambo 1.4. I never hooked it up backwards, and I measured the voltage on the plug before plugging it into the Rambo board:

12v on the four pins for power input B and C.

Only the steppers and power connected (not connected to the PS in this shot):

All the fuses are good:

Everything looks good to me, but when I apply power, there’s no green light, no life at all. Am I missing something?

dart1280 · September 25, 2020, 10:15am

Ummmm…what is the meter connected to when the display reads OL. ?..coz if the answer is a fuse then the fuse is blown. According to the schematic, the green LED is fed by Vcc which comes from an LM22675 which is powered by VHEAT (the 12V input from power connector pins 3&4 via F3). Only other thing I can see is a jumper on JP3 will disable the Vcc power

RadioActiveLamb · September 25, 2020, 2:53pm

The meter reads 0 when the leads aren’t touching anything. You will hear a beep when there’s continuity as I measure each of the three fuses. None of the fuses are blown.

I don’t understand what you mean by a component being powered by VHEAT. I have the 12v power connected to only B&C of the Power Input block. Do I need to jumper it to “A” also?

Also interesting, and I have no idea if its normal, the voltage drops to 0.9 vdc across the power input when connected to the board.

jchaager · September 25, 2020, 7:21pm

What kind of power supply are you using? 12V/5A is the recommended minimum size.

RadioActiveLamb · September 25, 2020, 9:38pm

I am using the power supply that came with the whole kit 12V 6A. Maybe I have a bad power supply?

turbinbjorn · September 25, 2020, 9:49pm

What reading do you get from the supply?

And did you check the screws?

(Sorry, I couldn’t help it. I’ll show myself the door)

RadioActiveLamb · September 25, 2020, 9:50pm

The voltage reading from the supply is the very first image. 12.76 volts. But, it drops to 0.9Volts when connected to the board.

vicious1 · September 25, 2020, 10:41pm

Take the green adapter plug off and cut the power supply cord to use the bare wires. That has proven to have a loose connection.

RadioActiveLamb · September 26, 2020, 1:07am

Genius!!! Thanks Ryan. Without the connectors, we have power, and it’s alive!! Now I need to learn how to use this thing

Alive

kvcummins · September 26, 2020, 2:55am

Just be careful of fire…

vicious1 · September 26, 2020, 3:12am

I wish I knew what the issue was with those connectors. Does yours work if you crimp down the outer conductor a bit?

dart1280 · September 26, 2020, 9:55am

Glad you got it sorted…damn the timezones!

FYI - the VHEAT is a term used in the Rambo 1.4 schematic diagram, it refers to the 12v power input for the ‘Logic, Heaters and Fans’ power input (B)
vheat

…you are lucky your power supply survived the short…not to mention your wiring. I can’t see the problem being a loose connection, much more likely that there is a substantial short between two pins in the connector block itself.