Onyx temperature loss - lack of power?

[analog_banana]

Can't get my onyx bed beyond 75 degrees without putting a towel on top...
Even if I leave it heating up for a couple of hours.

Based on what I can read here - Does this suggest any of these things?

My PSU is not powerful enough?
(I am using the proper PSU supplied with the kit)

Maybe the wires I used to connect the bed are not up to spec?
18ga is specced in the manual which is 1mm in the Kingdom of Britain.
I have used slightly larger than 1mm copper cables two of each for live and neutral.
The wires do get a bit warm.
Each cable is rated for 240volts I forget how many amps but it's at least 5amps per cable.
Would that be good enough?

Confession: I have just felt these cables as they go into the ramps board - they are warm to the touch...

Finally - when measuring the bed temperature I use a thermocouple pressed firmly against the 4mm glass on top of the bed. Is that an accurate way to measure?

By the way, the edge of the bed where the rings are less dense is 18 degrees cooler than the center.

[Eric]

I'd check your power supply voltages first. Make sure 12V is really 12V when in operation. If that checks out, see what the voltage at the bed is when it's heating.

What's your ambient temperature?

Cable gauge should be adequate, especially if you doubled them up like you said.

[analog_banana]

Wow thanks, good call - the voltages are low!

Bed connector(under load, warming up)= 10volts at board 8volts at the bed
Hotend connector(under load, warming up) = 10 at board 9.8 at nozzle
fans(1 x peek fan running) = 10.5 at board, 10.5 at fan

Should I check the stepper motors too to see if they are underpowered???

So I guess I need to figure out how to get 12v out of the above connectors.

I'm off to read up about Ramps 1.4 voltage...

Thanks again. This is not easy!

[mhackney]

You need to measure the output voltage from your power supply. The Onyx is a hog, you might consider a separate 12 V supply for it. You could pick up an old PC power supply from a used PC shop.

I run an after market 12V supply for everything else and a 24V 14.5Amp supply for the Onyx. It was a great investment!

cheers,
Michael

[analog_banana]

Well I double checked, and when only running the hotend, everything else off, the board is only giving 10volts to the hot end.
So aside from the bed problems I think not enough power is getting to any of my components...
So perhaps something is underpowered here - or wrong?

So next, I checked the power going into the Ramps board and it's 12volts going into both power input connectors.
I see online that one should be 24volts to the upper input block! - could this be the problem.
Any Ramps psu experience?

[analog_banana]

Double checked my wiring and my info.
The 24volt thing is not applicable here. Please ignore that.
I have the correct wiring:
12V @ 5amps going to the hotend input of the board
12V @ 11amps " to the bed input.

For some reason I'm losing power and getting 10volts out the other end.

[Eaglezsoar]

Double checked my wiring and my info.
The 24volt thing is not applicable here. Please ignore that.
I have the correct wiring:
12V @ 5amps going to the hotend input of the board
12V @ 11amps " to the bed input.

For some reason I'm losing power and getting 10volts out the other end.

2 volts is too big a voltage drop. I would replace the power supply.

[analog_banana]

This machine is becoming Lincoln's Axe.

The vendor gave me a new extruder - the one originally supplied was thought to be no good.
SeemeCNC have advised me to pay out for a new hot end - apparently the one originally supplied is not good.
Now maybe I need a new PSU - Again I'm using the one that came in the kit - not good?

I understand that V1 of a machine will have bugs,
but I would expect some decent quality components that are fit for purpose - for the price I paid.

Ok, mini rant over...

Any recomendations for a GOOD power supply or combination of power supplies?
I'm really pushing to get this thing working.
I cannot thank everyone here enough for your help...

[Eaglezsoar]

You probably have a 450 Watt PC Power supply Type ATX in there now.
I would find the same thing but in a higher wattage like a 500watt or a little more.
There are other supplies that you will see that are 12Volts at 30 amps but I do not know a users skill level so I don't
recommend them because you have to make the cable that plugs into the wall and there is a danger of electrocution. So stick with
the PC ATX type as recommended above. Once you get the supply use the assembly manual to install it. It should look the same
as the one you are replacing. Here is a link to one just to give you an idea on pricing but you are in the UK I believe so your prices
may be different. Good Luck

[analog_banana]

Thanks! I guess I'll get another PSU.
Hope I can get the old one out and the new one in without total disassembly of the base!

Re Power:
if: 450watts gives 10 volts
500 watts would be 1.11 times more powerful, so would that give 10 x 1.1 = 11.1 volts?

So maybe 600 watts would be better?
600 watts = 1.33 times more powerful, so should give 12 volts plus change?

I am fine with electrical isolation, safety and modding, but I will choose the easiest route.
Ideally I'd like to know what PSU Is recommended by the manufacturere of the Rostock Max.
I have emailed seemeCNC.

[analog_banana]

Good news - It is possible to remove the PSU without total disassembly.
Bad news... It may be a massively underpowered PSU?
330W Average
480W Max

[geneb]

"480W Max" could mean "Yes, it did 480W for long enough to get a measurement and then it exploded."

At a _minimum_, I'd get a real 500W power supply. Something that's rated for 500W continuous. Try to avoid cheap power supplies if you can. I don't know if you can get them in the UK, but Thermaltake make excellent power supplies.

I noticed in an earlier post that you'd measured 10v at the RAMPS and 8v at the Onyx end, correct? That 2 volts is heating up the wires from the resistance of using too small a gauge. The Onyx bed wiring needs to be at least 14ga wire - this is one of the lessons I learned between the first and second editions of the manual. If you don't have any 14ga wire handy, just add an additional pair of 18ga to what you've got now. When you feel the wires to the Onyx, they should be the same (cold) as the wires going into the board power for the RAMPS.

Sagging power supplies SUCK! I've replaced the one in Orange Menace (the ratty thing lasted about two weeks) so I know exactly where you're coming from. You should get better heating out of the hot end as well once you've got more consistent power going to the resistors.

g.

[analog_banana]

I emailed John at SeemeCNC and it turns out I have one of a "defective batch" of PSUs that shipped with the kits.
Makes me feel a bit better about my build skills.
He has kindly offered to replace it, but I'll most likely get one locally.

So anyone reading l if your supplied PSU matches the photo above it may well be one of the "defective batch"
and may need replacing.

[Eaglezsoar]

I emailed John at SeemeCNC and it turns out I have one of a "defective batch" of PSUs that shipped with the kits.
Makes me feel a bit better about my build skills.
He has kindly offered to replace it, but I'll most likely get one locally.

So anyone reading l if your supplied PSU matches the photo above it may well be one of the "defective batch"
and may need replacing.

The one you have is also rated at 16 amps on the 12v rail, too small. And follow Gene's advice get a good supply with name recognition over the cheapest one you can find.
You get what you paid for.

[analog_banana]

Will do -
The manual is a bit vague about which yellow 12v wires to use. (it says "The longest")
I can't find any info on the web that explains which ATX wires are of specific ampere ranges.

I have some good multimeters but I've never tried measuring amperage, if indeed this power level can be measured with a multimeter.

[int2str]

Will do -
The manual is a bit vague about which yellow 12v wires to use. (it says "The longest")

All yellow wires are the same.

I can't find any info on the web that explains which ATX wires are of specific ampere ranges.

There is no difference in the standard. Different power supply manufacturers may choose to have separate 12V rails, but usually at the lower end of the price range, all the 12V cables are simply connected to each other.

[analog_banana]

I tried a 650watt PSU, There was only one brand at my local computer shop - a very cheap one..
No good - still undervolting just as before - maybe half a volt more on the hotend.
I know I'm an idiot for not buying a premium product - but I hoped that 650watts would give me some headroom.

Using a dummy load on the 5v Rail?
I Found this info on Reprap boards, anyone ever needed to do this?
You' may also need to connect the +5V to a dummy load (10 ohm, 10 Watt wirewound resistor is fine) or a fan or light that draws about 0.5A. Most ATX supplies need a load on the +5V rail or the +12V will be too low or it won't stay on when you put the motors on idle and turn of all your heaters.

How to check number of rails in your PSU
Also found this, could be useful:
If you have a multimeter, then you can turn off your ATX power supply, unplug it and check for continuity between all the +12V wires (yellow is standard). I'm guessing that they will all be connected to each other since the sticker only lists one +12V rating. That would confirm that you only have one +12V rail.

[analog_banana]

Probably gonna try this PSU next:

http://www.amazon.co.uk/Corsair-Builder ... B00ALK1GFC" onclick="window.open(this.href);return false;

[analog_banana]

More research - Maybe 10 volts in the 12 volt rail is normal?:

Quote from this discussion on cnczone:
http://www.cnczone.com/forums/controlle ... b6560.html" onclick="window.open(this.href);return false;

That's normal, if you take an ATX power supply and check the 12V wire you will notice it's closer to 10V than 12V. However if you really aren't getting the power you need and your supplying the proper voltage, the problem could be with the power supply your using.

So Maybe the 10volt thing is normal and I should be looking elsewhere for the fault?
I don't want to keep buying PSUs!

[analog_banana]

I have pulled a 650watt PSU from a really beefy HP Graphics workstation.
It's a very high-end, very powerful psu,
way more power overhead than the PSU supplied with the rostock max.

Guess what? No difference... Maybe .25Volts higher.. if that.
Just the same as the cheap 650watt psu, and the 480watt before that.
I'm pretty sure I can rule out the PSU as the problem.
from the cheapest tin box to the classiest, deluxe PSU...
I get the same power readings.

I am runnig 4x12v wires to the bed and 2x 12v wires to the hotend as per the manual.
I have tried 6x12v wires to the bed and 3x 12v wires to the hotend, but no difference.

Praying for strength and patience right now. (Who is the Patron Saint of Engineers?)

[Eaglezsoar]

What happens to the voltages going to the hotend if you do not turn on the Heat bed?
The Heat bed is the one that consumes the most current. I would be interested in the
voltages if you do not turn it on.

[analog_banana]

I have noticed no voltage sag under heavy loads on any of the 3 PSUs I have tried.

I have replaced the Heated Bed wire with REALLY thick copper wire (3mm thick) so there is no significant resistance in the system now.

SO - with the High Quality 650watt PSU and thick Bed wire i get this:

11v on the input terminals of the Ramps, both idle and under full load.
About 10.6volts on the Bed with and without hotend & fans on
About 10.9volts on the fan with and without the bed and hotend on
About 10.7volts ont the hotend with and without the bed and fans on.

My bed now heats up to higher temperatures, and quickly, so there is an improvement!!

I have tested a few more ATX PSUs (4 in total) and they all seem to give 11volts on the 12volt rail?
Beginning to wonder if all ATX PSUS are slightly underpowered??

I will probably try the dummy load on the 5V rail thing next...

[analog_banana]

Absolutely no difference in power output detectable with a dummy load on the 5volt rail.

See photo below for the spec of my "good" - I hope - PSU..

[analog_banana]

WHOA!!! UPDATE!!!!!

Tried a different Multimeter - I was using a cheap digital meter.

I rechecked using an Avometer Eight MK.6
(big, analog, reliable, original RRP approx $800, as used by the British Army)

12v on the input terminals of the Ramps, both idle and under full load.
About 11.5volts on the Bed with and without hotend & fans on
About 11.7volts on the fan with and without the bed and hotend on
About 11.5volts ont the hotend with and without the bed and fans on.

So I think I can say I now have a working power system...
I guess 11.5 is good enough.

Bad components + bad tools = wild goose chase
Really sorry If I wasted anyone's brain power by having a bad meter..

[Eaglezsoar]

Good job in diagnosing all of this. It's amazing that a meter would be that far off, It's also amazing that someone would produce such a meter.
You taught me something though, that even the meter can sometimes not be trusted. Happy Printing!