Calibrating Delta

dc42

The bed heater LED is next to the bed mosfet, between the VIN and bed heater terminal blocks.

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On the card edge, the two Heater LEDs E0 and E1 remain off, although they flash on momentarilly and then off. They stay off.

If I command Heater1(T0) = ACTIVE & setting 180°C LED E0 illuminates,

If I command Bed heater = ACTIVE & set any value LED E1 does not illuminate, yet power-supply fan ramps up speed on any value above 110°C, still the LED E1 remains unlit.

I will (yuch) pull all the connectors off and dismount the board to get a peek see underneath, although I did a fairly thorough check prior to mounting. I presume that 'spill', you intend solder flow & possible splashes?

I'll let you know. Thanks.

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@dc42

We were cross writing, so I missed your info re; LED placement, and as I have an external (not underneath heat-bed) enclosure, I can not see the LED with the lid mounted. But preliminary, the red LED is illuminating on power-up. I'm disconnecting the heater wires now..

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@dc42

Hi,

Ok, I pulled the board, carefully checked the bottom and top for splashes, hairs, etc, I saw nothing obviously wrong.

I performed your 'tests' and the red Bed LED remains illuminated, with or without Bed heater connected or with the SD card

Yep..

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@dc42

I reviewed the correct schematic (v1.02 as marked on the top silk), and I can't seem to locate which pin of the SAM drives the bed heater?

Worse case, I may have to ship the board back, but because I've waited nearly a year to use it, its likely out of warranty. Rather than ship the board..two weeks back, two weeks return, a whole month is fried, I'd rather either fix it myself or use an external bed driver if I can. But I don't see where the pin comes out on the expansion connector. What are your thoughts on that? Any recommendations for an external driver?

Thanks - 3mm

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@DC42,

Ok, referencing the sch, I found the Bed (HEATER0) signal, I initially missed U11, another clever strategy.

HEATER0 & BED_PWM come on TP6 & TP9 but I don't see that either signal are routed to the Expansion connector. Am I missing something again?

Thanks

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dc42

The on-board heater signals are not routed to the expansion connector, but there are 5 additional heater control signals that are. They are 3.3V level, active low. So you should be able to use one of them by connecting the input of a good DC-DC SR (see recommendation in wiki) between +3.3V and your chosen heater signal. Or, if you are not using the E1 heater output, you could connect the input of your SSR or a mosfet switch to that output. Use M140 to re-assign the bed heater to a different heater number.

You can measure the voltage on BED_PWM (TP9) to help identify where the fault is. It should be 0V when the heater is commanded off, and around 5V when it is commanded on.

Which country are you in?

HTH David

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@dc42

Hi...yeah, I'm must be slipping, I re-looked at the sch and completely missed how the LED is wired. Fault can't possibly be caused by the cap being leaky. I'm gonna have be a lot more careful in determining the problem. It could be caused by an interlayer short, perhaps in the area of the sink-thru's.

I do have a hot rework station, and the FET is available.

I'm in California, USa. I got the board from FilaStruder. They are good guys.

I'll poke around with scope later today when I get back from my errands.

Thanks for your help.

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@dc42 said in Calibrating Delta:

The on-board heater signals are...3.3V level, active low....use one of them....with...a good DC-DC SR (see recommendation in wiki)...

...use the E1 heater output...to...connect the input of your SSR...to that output. Use M140 to re-assign the bed heater to a different heater number.

HTH David

David, et al,

I acquired an Auber Inst SRDD-100 (I've used their SSRs for other things, I found them to have good prices and quality parts, thx for the referral). I installed the SSR 'puck' atop (w thermal paste) to my 350W 12Vdc Mean-Well switching power-supply after degreasing the area, I don't think it needs much of a heat sink, and the switcher does have an internal fan which kicks on when things get warm inside. I used 12Ga stranded Cu wire for the SSR and the 180W 12Vdc (0.8Ω) round PCB/aluminum bed-heater assembly wiring.

It works, though not well. I've expended a fair amount of time doing the auto-temp tuning which has it working, sort-of?? If I enable PID, it never attains 110°C in less than 10 minutes, and then does so, barely. I can't cause to attain 120°C. I fiddled around with the PWM setting until the system would not emit error: heater-fault.

I noticed that the DWC displays 'Cal Vin = 11.5'. I have multipe DVMs, a Fluke, an ExeTech and an HP bench version, all measure 12.10 Vdc. I don't know how that calibration reference is derived, or if its sub-normal. In any case, I double checked all my wiring and Voltages, at the Power-Supply, at the screw-terminals on the DUET-E (v1.02) and on the bed terminal-block. The Voltages are ok. I also double checked my power-budget, I should have around 100W over-head, and when all the steppers are running, and both heaters are heating, the power-supply Voltage does not sag. The AnyCubic factory did not include the heat-bed with their version of the AC Kossel Linear-Plus that they sold me, but I bought the bed later from them. So it should work??
If I run the bed heater in bang-bang, it heats up, but then its dodgey and I can not attain 120°C.

The G/M codes are very functionally capable and it seems that I'm missing something, unless the bed is just somehow bad?

Just an FYI...thx

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dc42

What type of bed heater is it? If it's a PCB bed heater, those are frequently under-powered. I think one of the problems is that the Chinese manufacturers don't control the copper thickness very well, so the heating power varies a lot between different samples of the same PCB heater.

If your PSU has a voltage adjustment pot, you can turn it up to get extra bed heating power.

The VIN voltage measurement on the Duet uses 1% tolerance resistors in the voltage divider, and the +3.3V supply as the voltage reference. The output of 3.3V regulator chip has a tolerance of +/-2.5% worst case and +/-0.5% typical. So even if you are really unlucky, the voltage reading shouldn't be significantly more than +/-4.5% off.