heatbed (yes mine doesn't work as well)

Hi all,
I'm that new that this is my first post so plz be gentle
Well, finished building the kossel mini delta printer (took me ages) my setup:
Kossel mini, Arduino mega 2560, Ramps 1.4, ATX12V P4 PSU.
Firmware from this link isn't latest - I know but used his manual..
All motors OK,
all switches OK,
Hot end OK (connected on D10)
heatbed - not ok (connected on D8)
The heatbed resistor reads 1.6 [Ohm].
In pronterface setting bed to 110 turns out 0[v] on D8.
I have failed getting readings of the current since when testing it (disconnected + from ramps connector [the 11A + in this pic] connected + of voltmeter to it and connected - voltmeter to the ramps connector) I got 0 but when testing voltage of input I get stable 11.56[v].

Please advise..
Best regards.

Put one meter lead on the negative terminal of the 11A connector and the other lead on the positive terminal of D8. Do you read around 12v on your meter? If not, check the continuity of the larger yellow fuse.

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Waitaki 3D Printer

Thank you for your input.
I've tested the from negtive 11A to both positive & negative D8 I get 11.54[v] they have the same voltage compered to GND.
It didn't changed both when brought system up & when sending command to heat the bed the voltage doesn't change.
The big yellow fuse seems OK..

1. when\why I have 11.54 on BOTH D8+ & D8- [is there special case for that?]
2. where in the firmware it sends command which will tell ramps to activate D8?
3. if my psu isn't delivering 19A (it is ATX12V P4 480W and it is written on it that it can support 12V 19A) and not even 11A will that explains what I'm seeing?
4. My ramps 1.4 arrived soldered - if there is a shortage (it seems that both D8- and D8+ are getting Vcc) where should I look for it?

Thank you again.

The reason you see 12v on both terminals is because the Mosfet for D8 is not providing a ground path to switch the bed on. This is either because the Mosfet is faulty or because it is not receiving a signal from the Arduino to switch it. To check the Ramps solder track, put a meter lead on the negative input of 11A (or 5A) and the other lead on the right hand pin of the Mosfet - there should be no resistance.

Is the LED for the Mosfet illuminating when you switch the bed on in your host software?
A 480W PS is plenty enough for the job.
Have you got your firmware correctly configured for a Kossel Delta?

Edited 1 time(s). Last edit at 08/07/2014 04:18AM by waitaki.

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Waitaki 3D Printer

Thank you for your replay!
I think your correct - when switching the hot end the I see red led on, when switching the heat bed I don't see any led on.
Yes my board is configured with:
[Marlin\Configuration.h]
#ifndef MOTHERBOARD
#define MOTHERBOARD 33
#endif

But after what you wrote I've made a test and added
[Marlin\Configuration.h]
#ifndef MOTHERBOARD
#define MOTHERBOARD 33
#error
#endif

It should have gave me an error but... it didn't..
So I downloaded the latest made the same test (after making sure it is with MOTHERBOARD=33) I've made the same test & got an error.
When I'll return home I'll test it.

Thanks again

waitaki Thank you!
following your guide lines I've resolved the issue.
I've moved to the official delta.
I'm not sure it is a bug since I've just began to learn the firmware but although I've selected #define MOTHERBOARD 33
This DIDN'T ENFORCED the "TEMP_SENSOR_BED" to be 1 on the configuration file hence has you mentioned it wasn't active.
(is there a reason for that since " 33 = RAMPS 1.3 / 1.4 (Power outputs: Extruder, Fan, Bed)" made me think that fan & bed & extruder will be activated.. )

Now that it's working I noticed huge delay from the moment I tell the bed to be activated till the moment the light is on (about 3-4 seconds) compering to hot end which turns on immediately.
Is this behavior is OK?

It's probably ok - mine takes a second or so but what's important is whether the bed is now heating up and operating normally. I am not familiar with that particular machine but 33 is correct for your Ramps. I wonder sometimes whether Marlin has a mind of its own!

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Waitaki 3D Printer

Quote
polkary
waitaki Thank you!
following your guide lines I've resolved the issue.
I've moved to the official delta.
I'm not sure it is a bug since I've just began to learn the firmware but although I've selected #define MOTHERBOARD 33
This DIDN'T ENFORCED the "TEMP_SENSOR_BED" to be 1 on the configuration file hence has you mentioned it wasn't active.
(is there a reason for that since " 33 = RAMPS 1.3 / 1.4 (Power outputs: Extruder, Fan, Bed)" made me think that fan & bed & extruder will be activated.. )

Now that it's working I noticed huge delay from the moment I tell the bed to be activated till the moment the light is on (about 3-4 seconds) compering to hot end which turns on immediately.
Is this behavior is OK?

Those configurations tell the firmware which pins are used for what purpose, they are not going to enforce anything except the extruder. You can run 33 and not have a bed or fan, they are not required items. As far as the firmware is concerned, if you do not select a thermistor/thermocouple for the bed, it believes you do not have one and ignores any commands and configuration related to the bed.

Thank you.
Could you kindly explain to me why there are(from configuration.h):
// 33 = RAMPS 1.3 / 1.4 (Power outputs: Extruder, Fan, Bed)
// 34 = RAMPS 1.3 / 1.4 (Power outputs: Extruder0, Extruder1, Bed)
// 35 = RAMPS 1.3 / 1.4 (Power outputs: Extruder, Fan, Fan)
If I understand correctly I could have set my board to 33/34/35 right? as long as I set the outputs of extruder,fan,bed etc' correctly..

Quote
polkary
Thank you.
Could you kindly explain to me why there are(from configuration.h):
// 33 = RAMPS 1.3 / 1.4 (Power outputs: Extruder, Fan, Bed)
// 34 = RAMPS 1.3 / 1.4 (Power outputs: Extruder0, Extruder1, Bed)
// 35 = RAMPS 1.3 / 1.4 (Power outputs: Extruder, Fan, Fan)
If I understand correctly I could have set my board to 33/34/35 right? as long as I set the outputs of extruder,fan,bed etc' correctly..

There are a limited number of outputs on RAMPS, these configurations allow you to run different setups. If you do not need a PWM controlled fan, you can run 34 and have 2 extruders because it will then use that PWM to control the extruder heater. If you select 35, you will have 2 PWM controlled fan outputs. These configurations change pins.h and how the pins are used in the firmware.

Thank you!