No power to bed or hot end when connected.

[Durandal]

Alright, my machine is brand new and unused.

Neither the heated bed nor the hotend heat up. With the leads disconnected from the terminals the red light for heat1 on the Rambo will come on and there'll be 12v across the terminals, but if I touch the leads to the terminals the light goes off. The hotend thermistor doesn't work, I have one on order from Seemecnc, but the bed thermistor does, so for testing I have this connected to T1.

There's continuity between the leads on the bed and hot end, so it's not a soldering issue, except the hot end thermistor, and I've tried two power supplies with the same result. Do I have a bad Rambo? Anythoughts for further diagnosis.

[Polygonhell]

Alright, my machine is brand new and unused.

Neither the heated bed nor the hotend heat up. With the leads disconnected from the terminals the red light for heat1 on the Rambo will come on and there'll be 12v across the terminals, but if I touch the leads to the terminals the light goes off. The hotend thermistor doesn't work, I have one on order from Seemecnc, but the bed thermistor does, so for testing I have this connected to T1.

There's continuity between the leads on the bed and hot end, so it's not a soldering issue, except the hot end thermistor, and I've tried two power supplies with the same result. Do I have a bad Rambo? Anythoughts for further diagnosis.

RAMBO 1.0 or 1.1?
Do you get any output in the host window if you turn on all the outputs.
If it's the 1.0 with the poly fuse, the odds are you are over powering the fuse.
What is the measured resistance on the hotend and bed heaters?

[Durandal]

It's a 1.1 with the automotive fuse. The fuse is good still.

Resistance on the hotend is around 4ohms and the resistance on the bed is 1ohm.

[Durandal]

Well, I got the replacement Thermistor last night, I'll see how that works out tonight. Is there anything I might be missing?

[Durandal]

Got everything wired up with the screw in thermistor from ebay, reads good in repetier host, IE both bed and hot end thermistor read the same, but still nothing at the hot end, although LED4 stays on when I have the hot end connected to Heat1. I did find that by connecting the hot end to fan1 that it heats up just fine, but doesn't stop heating so I obviously can't use that terminal.

So at this point I've ruled out:

Thermistor Issues
bad wiring
power supply issues


About the only thing that I haven't tried is to re flash the firmware, which had to be monkeyed with in the first place for my extra tall build height, but I'm fairly certain that I've got a bad RAMBo board.

[Durandal]

Got replacement board from SeeMeCNC for the cost of shipping the bad one back to them, solved issue right away.

Thanks.