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I've come across a number of TM pumps that are of the split design; as I understand it, they're used to pump two chambers to different vacuum levels using 1 pump and are typically found in mass spectrometers. As I see it, the input to the lower (relatively) vacuum stage could be blanked, thereby creating a single input pump pumping to the higher vacuum level that the pump was originally used for.
Is there anything wrong with my reasoning?
Without knowing the exact model of pump I can't say for certain, but in general yes you can just blank off the unused port with no ill consequences. The second port is just there because it lets you pump down the sample chamber quickly even with a weenie backing pump by using the first few stages of compression of the main turbo.
The pump I'm looking at is an Edwards EXT200H. The guy also has a Varian single stage pump for the same asking price, but it's been dropped and has suffered external damage, although he claims it turns smoothly. I'll have to cobble together my own controller, but that's not as issue for me!
Yeah it will be fine to run that pump with the auxiliary port blanked off.
You might want to ask the vendor if he has the controller for it, the EXDC 160 controller for that pump is integrated in the connector for the pump.
http://docs.edwardsvacuum.com/P450-0...396-45-880.pdf
Even if he doesn't, its honestly probably not worth building it yourself since you can get the controller for about about the cost of he connector...
ex https://www.ebay.com/itm/T161921-Edw...C/293202138412
You need to double check the voltage, most pumps are 80v but there are also available in a 24v version that needs a different controller like this one
ex https://www.ebay.com/itm/Edwards-EXD...r/254443598082
Well I picked up the pump today and it's in very good condition; unfortunately he doesn't know where he put the controller, this is a common issue with items from him, he tends to disconnect cables and lose them. I've order an EXDC 160 for a very sensible price, although I wasn't aware of the different voltage ratings so I need to look into that.
Incidentally the Varian pump was brand new but the packaging inner bag split when he unpacked it and the pump landed on the base of the motor. It does turn freely but I couldn't be certain whether or not the bearings have taken a knock. He also has one brand new Varian controller and another that looks to be unused.
Edit: The pump is a 24V model and the controller I ordered is the 70 - 85V version :(
Here you go, but it seems to be missing the "drag" detector that shuts down the pump in case of leaks or failure to get up to speed.
Otherwise a very solid design, pretty much all software.
https://github.com/NiklasFauth/stm32-turbotronik
https://hackaday.com/2018/04/28/an-o...mp-controller/
Two TMP150s reside at Casa Mixedgas. One of mine is missing the controller but otherwise good.
That is why I was looking at DIY / DBSE*
https://photonlexicon.com/forums/images/icons/icon6.png
*Done by Someone Else
Steve
Thanks Steve, that's kind of the way I was originally heading; I suspect that may be easier than converting a high voltage driver to a low voltage driver.
Just checked the schematics, now I have a use for all the IGBT modules I was given!
Doing some research today has left me a bit confused, the spec sheet fo0r my pump states it's 24V, but the pump would have shipped with an EXDC 160 controller fitted. When I look at the mains powered controllers, there is no differentiation, all of them seem to put out 90V p-p; would I be right in thinking that the EXDC 160 also puts out 90V p-p and the voltage rating is the supply voltage to the controller?
Have you any photos of the bits in question?
I have zero expertise in turbo molecular pumps, but I know someone who might be able to help at a local lab who has several of these.
You can give it a try, I doubt that an 80v controller will damage the pump. Most likely scenario is it will blink angrily at you, but it might also be able to run the pump at reduced power. I have only used 24v edwards pumps, so I am not sure what the deal with the 80v stuff is.
My understanding is that the EXT pumps were originally all '80v' with external controller. They are being replaced with the nEXT which are 24v with an integrated controller. In order to extend the life of the EXT series they released EXT pumps which which were wound with a 24v motor so that they can be used in the 24v nEXT ecosystem. The magical link to make them compatible with the integrated controller nEXT series components is the EXDC controller, which mounts on the pump and provides the same 15-pin d-sub connectors that the nEXT pumps use, effectively turning a 24v EXT pump into a nEXT pump (albeit lacking the rs485 monitoring and other newer nEXT features).
I am not sure where the 80v EXDC plays into this, maybe after they designed the 24v version they figured they might as well release the 80v version for the legacy users running 80v systems? NOTE - the pinout of the 80v EXDC controllers is completely different than the 24v ones, probably to match some older controller pinout. As far as I know there are no inbetween series that run an 80v pump from a 24vdc power supply, or any 'controller controller' units that provide a user interface for the 80v pinout such as the TIC series for the 24v nEXT compatible stuff.
I found one old catalog which explicitly calls out the difference between the 80v and 24v systems (see page 3 and 7 etc) and the controllers associated with each. Curiously, it does not acknowledge the existence of an 80v EXDC controller--maybe it hadn't been released when that catalog was published? http://www.ptb-sales.com/manuals/edwards/ext.pdf
Thanks Krazer, that's a big help, even if it's not the answer I wanted!
Pics for Dan!
The controller that I bought:
Attachment 56370
Attachment 56371
My pump:
Attachment 56372
Attachment 56373
I'll ask my friend and let you know if anything useful comes back.
In other news: Could you attempt to offer this seller a fraction of what he's currently selling it for? (He accepted offers on the other two sold).
https://www.ebay.co.uk/itm/Edwards-E...r/163432376517
Thanks Dan. I'll try making a silly offer on that controller!