Gen7 v1.5 Teacup - stepper motors - no sign of life

Hello All!

This is my first post on this forum, so I'd like to greet everyone.

Lately I'm trying to get my Prusa Mendel i2 into operation.
I'm using Gen7 v1.5 electronics with teacup firmware.

I've encoutered 2 main problems so far.

1. The stepper motors give me no sign of life at all. No souds, no rising temp., no holding torqe.
The stepsticks were adjusted. The voltage on "ENABLE" pin drops to 0V when the motor should get the info to move, but at standby it's only 1,16-1,2V.
There is 5V on VDD pin and 12V on VMOT pin.
The motors coil wiring was checked. When I'm rotating motor shaft by hand im registering some voltage on multimeter, so I assume they are allright.
The 4 stepsticks I bought were new, so I assume there is a low possibility that all 4 were damaged from the beginning.
The opto endstops are plugged and operable the right way, but I think there sould be no influence from their side to move the motors some at all.
I don't know what else could I check?

2. As the second problem I found that the Bed Heater output does not work after I've uploaded the newest Teacup firmware. It used to work with some older version which I've uploaded some in the mid 2013 (i had to postpone my project for a few moths). I've checked the pinouts in Teacup - look it is OK.
Additionaly I've noticed that when the power source is on standby I have some 0,2V on the both heater outputs, and about 0,9V (heater LEDs are "glowing" a little bit) when the power source is full operating (this situation was the same with the older firmware). I have checked both mosfets, and they seem to be OK. Is that normal or/and acceptable?

Please help!

PS. I forgot to mention that I'm using Pronterface to send the commands, but I've also tried the Reprap host software. It seems to be OK with pronterface though.

28.02.2014:

An update for today if somebody is interested. I have made some further investigation.

I've read the discussion Getting movement with Teacup + Gen7 1.2 — resolved as it sounded quite similar to my problem. Unfotunately that was not a solution for me. However, durig all the checks I have noticed that my ATMega is getting warm (or even hot) after some time. Until now I have used my elecronics only for a short periods of time so I couldn't observe that.

Additionally - earlier I have tried to port the Test_Motors program, from the disscusion above, onto my Gen7 v1.5 by changing the pinouts and commenting the max optos definitions, but it has shown no results. Even the powersource was only in stanby mode so maybe i have done something wrong?

About getting ATMega's hot i found a disscusion AtMega 1284P-PU Getting hot. I knew all the "voltage tests" on my PCB without ATMega and Stepstics was OK. I have then checked all my stepstics one after another installed onto Gen7 but without ATMega on board. Following that I have revealed that one of the stepstics is "producing" 0.4V on the ENABLE pin, and about 0.63V on DIRECTION pin. However the ATMega is getting hot even without that bad stepstick installed, so now I'm wondering if there is any other shortage somewere i can't observe or the ATMega is already damaged permanently. I have one more spare ATMega ready to bootload, but I would like to hear Your opininon before I'll put that new one inside.

For the heaters output issue, I've measured about 0.2V on the ATMega pins responsible for heater signals, so maybe that is the reason the MOSFETS are "leaking" a little bit, however the bed heater still does not work.

Summarizing all togheter I hope that changing the ATMega for a new one could fix at least some of these issues.
Anyone could share his opininon? Thanks in advance.

Edited 2 time(s). Last edit at 02/28/2014 04:29AM by dexer.

I couldn't edit the above post so I'm writing a new one.

I took a brand new ATMega, bootloaded and flashed with Teacup firmware. Unfortunatelly no success - motors are still dead. However Bed Heating output finally works (which is quite odd for me.

I've checked the voltages on "Enable" and "Direction" pins on ATMega one more time but in two cases - one with the stepstick installed and one without it - that has shown me that my assumtion to have at least one good stepstick (from 4 brand new) was probably wrong.
Without stepsticks the voltage o the above mentioned pins is 5V. Of course in their appropriate state. After installation of any stepstick the voltage ot these pins drops to about 1,2-1,4V and the ATMega starts to getting warm.
I couldn't measure any voltage on these pins (on stepstick) when ATMega is not installed on the board.

Does anyone have any other way to check/test stepsticks, and what may be the reason of this situation?

Sounds like the stepsticks are causing a short circuit on the output pins of the ATMega. I'm surprised the ATMega hasn't died because of this. You could check the resistance between the enable and ground pins of each stepstick, as well as the resistance between direction and ground pins. If you get a small value, there is a problem with your stepstick. According to the datasheet for the A4988 (I'm not sure which chip your stepsticks use, but it should be similar), the logic current draw of the stepper chip is <1uA typical, maxing out at +-20 uA. This means the resistance between the logic pins (step, direction, enable) and ground should be at least 250 kOhm.

If all four stepsticks are bad, I would return them for a refund or replacement.

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Thanks NewPerfection!

I have the A4988 drivers. You gave me a good idea - I have totally forgot about the first ohm law
I looks, that all my stepsticks are damaged somehow. None of the logic pins are even close to 250kOhm. Some have the resistance above my multimeters measure capability - so its bad (over200MOhm). Some have the resistance about 100kOhm so its closer but still not correct. Only the MS1 MS2 MS3 are as in spec (100,50,100).

I have also measured the resistance on the Vdd and Vmot pins. If I understood right they should be respectively 0,6-1kOhm and 8,7-17,5kOhm but they also not in spec.

My next step - exchange the stepstics for some others.

HA!!! Finally!!

New set of stepsticks (actually pololus this time) - new hope!

From the set of four just one is somehow damaged. Three are moving my motors smoothly and quietly after regulation.
One is just making my motors to buzz (which is still better then nothing) - no matter how I set the Vref. Maybe there is a way to repair that?