Sorry to keep dredging up this thread.
So the 450W PSU has been fine, but I’m finding that it heats up the dual extruder and bed slower than the stock PSU. So I’m wondering if I need more than the 18A this thing is putting out. The next step up would be a 500W 21 PSU.
Thoughts?
Something else is wrong. Two nozzles should draw 80watts max together, and the bed heater draws 240w max. That’s nowhere near your capacity, check to see if it is putting out the correct voltage, and check all connections. Going to a bigger psu wont help, the one you’re going from has a ton of overhead already, more won’t do anything.
If you look at the back of the heater you will read it is a 360 watt heater, and the RAMBo can draw up to 10 Amps itself. so that works out ot up to 600 Watts of power you can demand from the supply.
Just saying!
24 volts and up to 25 Amps. It is not likely to draw that much, but that is what the fuses are rated for that are being used. 
Generally you don’t want to tax a power supply more than 80% of it’s capacity. If anything, you want something that is ~20% more capable than what you will actually be using. The equipment will also run cooler since it’s rated for higher loads.
Funny this is dredged back up…
I was reading reddit last night, and someone posted something similar in the RepRap subreddit. They added things up and it came out to 23A of current if everything is going full blast. The only difference seems to be the 240W for the heater, which is really 360W as pointed out by kmanley57.
Not everything will be drawing at at the same time, but if they were its a 600W+ to keep up with all the components. I’m looking at the 750W 24V which is 31A…
On an observation note, the printer is a bit slower to heat up… no historical proof, but the timing of the pre-heating of the bed and T0 is off in my Octoprint start script. All the timing worked so that the two extruders and bed hit 245C almost simultaneously.
Here’s the reddit user’s tally of current draw:
So a little quick research: Silicone heater 8-10A, Steppers 1.5A (@6 = 9A total), Heater Cartridges 2A(?) (QTY 2= 4A)
So looks like I need ~23A if everything is drawing max current simultaneously.
The Z axis steppers are almost never engaged while the X and Y steppers are. Same with a second extruder while the first is in use. That being said, there are other amp draw parts in the machine that are significant as well. The Rambo board itself probably uses at least half an amp, the GLCD draws either half an amp or 1 amp, depending on which variant we have (i didn’t open the case to check) and depending on how many fans you have, there is another .5 or so amps right there. Even with all that though I would think you would have a difficult time exceeding the PSU rating unless you were dual extruding polycarbonate onto a 120c heated bed with both extruders running constantly, all fans full bore and the z axis running up and down for some reason at the same time. Then again, the power supply could be over rated and actually producing less current too. It’s not an unheard of issue, though the meanwell ones should be pretty solid.
So it looks like the PSU enclosed in the TAZ 6 is a 500W 24V 21A power supply… actually a 504W:
http://devel.lulzbot.com/TAZ/accessories/Pomfret/production_docs/Power_supply_BOM.ods
Specifically the Mean Well RSP-500.
I have been trying to figure this out myself too. Let me know if you can save me some time. It would be very appreciated
It’s actually pretty simple, I just got a cord from IT-works, The red and white wires go on +, Black and green on -. Case for Meanwell NES-350-24 PSU for use on Taz Printer by gghouck - Thingiverse is my model, You’ll have to look up the specs for the power supply it was designed for (NES-350-24) and see if it will work for yours if you get a different model. I’m told that 350 is actually small for a Taz but I’ve had no problems, the bed and extruder actually heat up faster than with the stock PSU.
It seems Meanwell PSU are on Ebay in spurts and the prices show it. I bought a 15 volt, 480 watt unit for less than $35 new and shipped, but a month before the cheapest was over $90.
Even the 500 watt meanwell is only like 90 bucks which is supposedly the same unit in the 200 dollar lulzbot one…
The meanwell 500 watt 24 volt power supply by itself (which the least expensive one I see is $120) is a bare psu. The lulzbot one has a powder coated metal housing, switch, power plug, cord socket, cord wire to and from the psu, the wall and the taz, and the internal wiring. Factoring parts, labor and the fact that they are a buisinesd and need to make profit, that’s not an unreasonable cost at $200. You can certainly make your own if you have the skills and itworks has them in stock, but you are still at least in the 160 range even at that.
Thats true but the only thing that worries me is the fact that they will only warrant it for 30 days where buying the unit itself is warranted for 3 years… also alot of sites offer big discounts for bulk ordering which is what i assume Aleph would do. But i dont know im just still mad that my power supply died so soon even though i would completely disconnect it when not in use.
I recently finished my PSU upgrade with integrated volt and amp meter. My PSU is a meanwell 500w 24 volt unit and is set to 25.3 volts. At that I have yet to see it hit 15 amps. It comes close when the bed is heating, the nozzle is heating, and I home all axis, but once the bed is up to temp it goes down to between 5 and 8 amps. Seems the bed heater draws 10 amps at that voltage, likely less at 24 volts.