TMP Diagnosis

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
Jackson Oswalt
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TMP Diagnosis

Post by Jackson Oswalt »

Hello!

As I've mentioned in some of my previous posts, I am a proud owner of a turbo molecular pump. I got the pump off of eBay for $160 and the drive unit from a YouTube channel called "Gooferking Science" for $100. He had the same model pump as I before he broke it in a freak accident. Thankfully, the drive unit was fine and he sold it to me along with all the cables.
Turbo Molecular Pump (side)
Turbo Molecular Pump (side)
Turbo Molecular Pump (top)
Turbo Molecular Pump (top)
Turbo Molecular Pump Drive Unit (front)
Turbo Molecular Pump Drive Unit (front)
Turbo Molecular Pump Drive Unit (top without cover)
Turbo Molecular Pump Drive Unit (top without cover)
Turbo Molecular Pump Drive Unit (side without cover)
Turbo Molecular Pump Drive Unit (side without cover)
Sound like a bargain for a TMP, doesn't it? Well for the most part it is. There are zero noticeable scratches on the actual pump, the blades spin quite well when I push them with my finger, and all the o-ring are in great shape. But how does it run? There's the catch. I've had the pump since February, and I still haven't been able to get it to work. The drive unit powers up, the "ready" light comes on, I flip the switch and the "accelerate" light comes on, but it doesn't go. It just sorta stumbles. It tries to speed up, but then it stops. If I leave it to struggle like this, the fuse will eventually blow. So, in this post I'll say everything I know with the hope that someone has an answer. Something tells me this will be rather long, so bear with me.

The beginning:

The only thing suspicious about the shipment and purchase was the day the pump arrived. It was soaked in oil. I guess the pump had flipped upside down during shipment and all the oil had spilled out. Could it be possible that the spilled oil could have clogged the motor or something? That would explain the symptoms, but that doesn't seem likely. Since then, the pump has been dried off and stocked with new oil. For anyone that might be thinking of getting a TMP, you should know that oil is $50+ for 3oz.

The fuse:

The original problem that I found with the TMP was that it was missing a fuse. "Gooferking Science", the guy who sold it to me, explained that he had taken it out to use on his Variac. No problem, I'll just buy another one and it'll work, right? Nope. After at least $50 had been spent on various fuses, I came up with zero results, other than that it started stumbling as I explained above instead of just not doing anything. I reached out to many people: Gooferking Science, other people on eBay selling the same drive unit, and Rigaku (who has denied making the pump despite the fact it says "Rigaku" in ten places). In the end the only answers I got were "I don't know" or a diagram of some random TMP drive unit. After all this, I started to think maybe the fuse wasn't the problem.
Fuse Holders
Fuse Holders
The switch:

Because this technology is from 1995, it's quite difficult to locate all of the pieces. The most important thing I couldn't find was the switch that starts the acceleration. Fortunately, there's a rather simple way to fix this. As I learned from Gooferking, you can stick to leads of a switch into the bottom two holes of the "CN4" ports. You can see it in the picture below. However, despite the crudeness of this switch, I seriously doubt this the failure point. Gooferking used the exact same switch in the exact same way, and it worked perfectly. In fact, he has a video about it here: https://m.youtube.com/watch?v=A0v3tNCLqkA. So, I don't think it's the switch.
Ports "CN4" and "CN2"
Ports "CN4" and "CN2"
The roughing pump:

As of now, I believe this is the most likely place of failure: the roughing pump. My roughing is a Robinair 15500. It's supposed to get down to 75 microns at most, which isn't very good considering that's it's lowest pressure in a leak tight, outgassing free chamber. Something tells me that the TMP can't start at whatever crappy pressure the pump draws. Another reason why this would make since is because Gooferking had a rather nice pump himself (as you can see in the video linked above).
Pump Specifics
Pump Specifics
Now, for the fine details:

TMP Model: rtp300vrc
Year: 1996
Brand: Says "Rigaku". People at Rigaku want me to believe it could be a Varian.
Fuse 1 (for power to the drive unit): 15A. Came with the drive unit.
Fuse 2 (For power to the actual pump): 5A. Didn't come with drive unit.

That's all I got. I'm happy to answer any questions!
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Richard Hull
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Re: TMP Diagnosis

Post by Richard Hull »

Can't offer much assistance beyond asking if you took some of the photos lying down and some standing on your head.

Not a single image is oriented so that a person gravity locked to the earth can get a normalized view of what you have. In future, you might orient the images to appeal to those of us who walk and function upright on this planet. Just sayin'

I dare not suggest you are doing this deliberately, but given the reasonable conclusion that I don't think that given the random sample of images you have here that I would not get at least one single upright image in such a posting. (probability issue)

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
John Futter
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Re: TMP Diagnosis

Post by John Futter »

Yep
I've sid Tooooooooo many times how to resize/ resample so the pics obey gravity
but the great unwashed who post and do not read,continue to do this much like the idiots who hold their cell phones the wrong way to video
ie
https://youtu.be/Bt9zSfinwFA
Sarvesh Sadana
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Re: TMP Diagnosis

Post by Sarvesh Sadana »

If you click on the pictures they will be oriented the correct way. It appears to be an issue with the forum software itself rather than the pictures (though I have noticed that some picture types work better than others -- PNG tends to work better than JPEG).

Sarvesh
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Re: TMP Diagnosis

Post by John Futter »

Sarvesh
No it is not the forum software
The max size a picture can be is 1024 by 768 after that the board software starts doing things all on its own
Remember this site is free and content is paid for by Paul the Perfessor why upload way Too much resolution the end result is Paul pays and his generousity
may start to suffer
Just because you have the latest 12 terabyte camera in the recent hand implant --you do not not have to pollute the the storage with unneccessary gigabytes of wasted unrealizable picture content
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Richard Hull
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Re: TMP Diagnosis

Post by Richard Hull »

John is right. The photos I put up are all oriented correctly, are JPEG, and rarely exceed 500kb each. They all come out right side up and stay that way when clicked on to enlarge.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
David Kunkle
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Re: TMP Diagnosis

Post by David Kunkle »

I see a TC in the first pic, but you make no mention of what pressure the roughing pump achieves? You mention 75 microns like it's the factory rating. A worn pump or a small leak would easily put the pressure outside the range where a turbo can operate.

I'm still trying to fathom how you spent $50 in fuses?
If your experiment needs statistics, you ought to have done a better experiment.

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Rich Feldman
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Re: TMP Diagnosis

Post by Rich Feldman »

Just a few words about the photo size and orientation thing. I learned that recent smartphone & digital cam JPEG's generally include EXIF-format metadata. Jackson's fuse panel picture, for example, has lens, aperture, and shutter details. Also the camera model (iphone 7), exact date and time, and precise latitude and longitude of the fuse holders.

EXIF has a place for orientation of the cam when picture was taken, and maybe (independently) the desired orientation of the image for viewing.
There might also be image orientation details in OS-specific file attributes. It used to be that rotating a JPEG by 90 degrees was a lossy operation (as implemented in Windows Explorer, for example, which grayed out the rotate buttons if an image file's read-only bit was set).

Apparently, most of us see some of the "thumbnail" images in OP shown sideways (fuse panel) or upside down (rotary pump).
I find that if I click on one, the linked .php fetches the image and shows it the way Jackson intended.
But if I then save that image to file, or back up a step and "save target as" a file, the resulting jpg is oriented like the thumbnail
(probably fixed WRT the sensor in Jackson's iphone). Delving into the saved files, I found camera and exposure and geographic location, but nothing that looked like an orientation thing.

Right now it looks like this automatic rotation stuff isn't standard enough, or universal enough, to generally work across platforms.

I stand firmly in the camp which feels the burden is on the presenter, not to depend on new features that aren't mature.
Burden is _not_ on the forum software, or the individual reader, to update their software if it's less than (say) 5 years old.

Even when properly oriented, I think 4032 by 3024 pixel images are way too big for general posting, and not just because of the burden on Paul's server. Jackson's images would be no less informative 640 x 480 pixels.
1. Consider the burden on readers/viewers with a less-than-fast Internet connection, perhaps a marginal mobile link at their laboratory in the woods. Many of us have never streamed, or even wanted to download, a TV show or movie.
2. Consider readers/viewers with small screens. Automatic scaling, or easy panning around an image 8 screens wide, is like automatic rotation. Not universal enough to depend on readers having it or getting it.
My trouble-saving remedy of choice, when taking pictures for Internet forums that aren't mainly about photography: set camera to save pictures at much less than maximum resolution. It would be different if I were visiting Timbuktu for the only time in my life.
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Jackson Oswalt
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Re: TMP Diagnosis

Post by Jackson Oswalt »

1. Thermocouple vacuum gauge is having some problems. Still working on it.
2. $5 per pack of fuses. 10 attempts. The 5A rating has proven to possibly incorrect, despite how strange it may be.
3. I apologize for the inconvenience of the upside down photos. The TMP is positioned on the back of my desk, so I had to flip my phone to take the pictures. However, you can simply click on the photos and they will orientate themselves correctly.
4. If it's ok with you, I'd appreciate being let off the hook for this post.mIt doesn't seem like I'm going to get any replies other than that the photos are upside down.

Again, I apologize for the upside down photos. It won't happen again.
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David Kunkle
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Re: TMP Diagnosis

Post by David Kunkle »

Never heard of a Rigaku turbo. I looked at their site out of curiosity, and they obviously no longer make or sell turbos except as part of an instrumentation package. Maybe they used to sell turbos with their name on them long ago, but the manufacture was farmed out to Varian?

You said it was "soaked in oil" when it arrived. Did any oil get down into the vacuum inlet or outlet?

I'd get the TC fixed ASAP. Without it, you're working blind and just guessing that your vacuum is good enough to run a turbo and not ruin it.

Certainly appears to need a 5A fuse in the photo. Did it keep blowing fuses, and you just kept upping the amp rating on the next fuse until it stopped blowing?
I wouldn't attempt to run it again until you've pinpointed something. Next time something is liable to blow before the fuse, then you'll have a doorstop. ;)

My best guess is a short somewhere, or possibly oil on the rotors and stators would cause a lot of resistance when it's trying to speed up- assuming your vacuum isn't several hundred or several thousand microns.
If your experiment needs statistics, you ought to have done a better experiment.

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Richard Hull
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Re: TMP Diagnosis

Post by Richard Hull »

Turbos, especially used and second hand ones, purchased "at range", can be nothing but a pain. This is why a "no moving parts" diff pump starts off with a big advantage. Even a diff pump demands a good heater and a clean stack or you are back to more issues, still minor, compared to major turbo issues.

I have owned a perfectly functional 3" throat turbo with all cables and controller for 2 years, but will not install it as my diff pump is "plumbed in" and has worked well for 12 years in my fusor IV.
"If it ain't broke don't fix it" and "let a sleeping dog lie".

The real issue with any secondary high vacuum pump is size. Turbos are typically just the right size, (small). Diff pump offerings can be very inexpensive, but are often large, ( 4" throat or larger). These large diff pumps should be avoided.

No secondary pump should have a throat of 4-inches or larger. Plumbing adaptations on these larger offerings can be complex and costly if one is not a good machinist.

Good luck on getting the turbo to spin up

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Roberto Ferrari
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Re: TMP Diagnosis

Post by Roberto Ferrari »

Adding to Richard’s wise words, I would comment on Diff pump sources.
Of course eBay is a must but keep an eye to damaged or scrapped Mass Spectrometers.
From 20 years now it is common in those systems to use small diff pumps, air cooled, of small size.
Service people following employer policy replace all the pump. So search for damaged units at universities and labs.
Basic damage is heater cartridge burned off but most of them are replaceable. Some having a glass window can get a crack on it. Just take it off and weld a blank plate.
My small lab has 3 of those diff pumps on use and 3 more on the shelf, recovered from scrap.
Good luck!
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Richard Hull
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Re: TMP Diagnosis

Post by Richard Hull »

I will second Roberto's advice! Old, discarded, air cooled diff pumps off mass specs and helium leak detectors are ideal for the fusor builder. This are typically 2" throated pumps, but 3" is also common.

If you go turbo you need to be very careful in any purchase effort.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Jackson Oswalt
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Re: TMP Diagnosis

Post by Jackson Oswalt »

David,

Your guess is as good as mine when it comes to the brand. There's is no doubt in my mind that Rigaku had some part in the pump. It's branded as "Rigaku" everywhere I look, so my guess they had some sort of deal with Varian that ended quite some time ago. The pump is from 1995.

As for the oil spillage, yes, it was in the vacuum inlet as well as outlet (because that's where it spilled out of). Fortunately, I've seen a few companies that could clean/repair the pump if needed, though I am trying to avoid that. I'm sure the price would be in the thousands.

Until I'm certain that the turbo is busted, I'm going to stick with it. Despite it's issues, I still believe it was a steal.

Thanks for the responses everybody. It's been a big help!
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David Kunkle
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Re: TMP Diagnosis

Post by David Kunkle »

If oil was coming out the inlet port that connects to your vacuum chamber, I have little doubt that oil is covering your rotors and the rest of your insides, and that is your entire problem. Not quite sure how oil spilled out and "soaked" it. The oil is probably causing a lot of drag making it stumble when it tries to spin up.

And, yeah, sending a turbo in to a company is a minimum of $1500 to $2k and up. I've attempted to repair the same turbo twice with failure, while I know some here have seemingly repaired theirs successfully. Not sure how many would admit if it blew up after some too short a time period. ;) I've been known to go back to ebay and buy another used one that was compatible with the controllers I already had.

$160 is definitely a good deal........ on a good, working turbo. Apparently it was in good running order when the guy sold it to you. If you got it back in February, it's probably too long ago to complain that it was defective or packed improperly for shipping- but you could always give it a shot.
If your experiment needs statistics, you ought to have done a better experiment.

Ernest Rutherford
Jackson Oswalt
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Re: TMP Diagnosis

Post by Jackson Oswalt »

Thanks for the help. I just have one question: Isn't the oil supposed to be on the rotors so it doesn't wear down? Or is it only in the motor? Second, although I'm sure the oil is a major problem, I still bet that the cruddy vacuum is also a suspect. Again, thanks for the help. I'll look into cleaning the pump and with any luck it will be fixed.
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David Kunkle
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Re: TMP Diagnosis

Post by David Kunkle »

No, the oil or grease is only supposed to be on the upper and lower bearings that support the rotor shaft. This keeps the bearings from wearing down- not the rotor. The rotors' only job is to spin quietly in a vacuum- they never actually touch anything.
If your experiment needs statistics, you ought to have done a better experiment.

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Re: TMP Diagnosis

Post by Jerry Biehler »

Its probably not the oil. This pump is probably not a turbo-drag so it is going to need probably 50-100mtorr on the foreline for it to be happy.
Johan Reinink
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Re: TMP Diagnosis

Post by Johan Reinink »

Even in a terrible vacuum a turbo spins up to several thousand rpm, not really like "stumbling" described by OP. Usually controllers don't blow fuses, they just push on until either a timeout (some even skip this), overheating or normal operation.

How many pins does the connector to the turbo have? If you can find the winding connections (low ohmic, significant induction) you can check if all connections are equal to find a winding problem that could blow a fuse. Since the rotor spins well I'd suspect the controller. Also, that guy of the youtube video also has this video: https://www.youtube.com/watch?v=PjOTTGOunI4 I hope that's not your turbo!

The styling of the pump looks like a Seiko Seiki unit, I'm not surprised Rigaku doesn't know about this pump, it's not their market.
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Re: TMP Diagnosis

Post by John Futter »

Your robinair pump is not good enough!!!!!
The controllers ramp up at a set speed and if the foreline pressure is not good enough the controller senses this and will shut down or will blow a fuse due to excess current demand from a lagging rotor
You need to know that your foreline pressure is well below 1 x 10^1 millibar or 5x 10^-2 torr before attenpting to start one of these old pumps.
even if your robinair got to the approved vacuum the spinning pump would overcome it and stall on the resulting high foreline pressure

I see you still have not corrected your earlier photos and now probably can not
it has taken me a long time to spot the upside down robinair

Take the advice
get a diff pump learn how to use that with all the needed metrology (meters ie foreline and high vac)then try to apply it to your Turbo.
secondly most turbos do not like being in storage for very long as oil drys out in the wrong places.
some turbos have a repair program built in where they vary the speed and time to try to get the lubrication circulating properly before going to full speed
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Dennis P Brown
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Re: TMP Diagnosis

Post by Dennis P Brown »

I too got a working turbo, cable and controller for cheap ($10!) and it still works great after seven years. Pays to pay attention to junk being sold on ebay by companies that specialize in old/used gov/company surplus. That said, I use it only for a high vac system and not my fusor. My fusor uses a water cooled diffusion pump. That is easy to use, works great, never needs any real upkeep and came with a butterfly manual controlled gate valve/small chamber attached to it (has ports for vacuum gauges)- cost $110. Water systems are not liked by most people and are often a steal if one can deal with water. Bottom-line: Deals are there if one watches for them.

Cleaning the vans on a turbo isn't difficult but one has to be careful that they are not bent in the process; if that has already occurred then, yes, they can be straighten if bent (I've done this for a unit that was stopped by a bolt that fell into a running unit! It had numerous very badly bent vanes (no broken) and I fixed it and it runs perfectly now) but it requires patience and a bit of skill. If that is an issue, let me know and I can explain how to do it (but it is a dangerous process for the pump.)

The main rotor and vanes should spin (by hand) freely and there should be no sound of contact at all. If not, that must be corrected. Also, if the bearings are old/dragging then the unit will have issues (again, spinning it by hand should show this). Bad bearings will lead to a high current by the coils and this will either shut the unit down and/or blow a fuse (NEVER use a fuse greater than called for and NEVER replace a fuse more than once. That is just asking to burn out the coils or controller. Locate the issue and correct it.)

Some (esp. older units) turbo's allow the bearings to be re-oiled. Mine allows this and I have done it (required a few runs until the new oil out gassed.) The issue is the oil is very special (read expensive.) Turbos are nice for high vac but really are not needed for a fusor; yes, if one has one (and a gate valve) that will work well but a good DP has advantages and does NOT need to have a trap. I would never use my turbo for the fusor since the DP works so well.
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Rich Feldman
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Re: TMP Diagnosis

Post by Rich Feldman »

>> It just sorta stumbles. It tries to speed up, but then it stops.

>> Most turbos do not like being in storage for very long ... Some have a repair program built in where they vary the speed and time to try to get the lubrication circulating properly before going to full speed.


Hmm, maybe Jackson's controller picked up a Stuxnet infection.
Last edited by Rich Feldman on Tue Aug 15, 2017 12:41 pm, edited 1 time in total.
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Nick Peskosky
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Re: TMP Diagnosis

Post by Nick Peskosky »

Jackson,

If you are looking to make the leap into disassembling the TMP and cleaning it, I recommend you consult my older post on the ins-outs of this process: viewtopic.php?f=10&t=8602&p=59335&hilit ... rbo#p59335

If the turbo spins freely, my money is on the controller. Could you post pictures of the H-bridge circuitry? You may have a bad IGBT/FET pair or a hall effect sensor which is failing to pick up on the shaft rotation -> causing issues with proper sequencing of the phase rotation. Have you checked the output waveform of the PWM driver or the actual winding outputs? Misshapen waveforms at either or these debug points may indicate either a logic issue/timeout or a damaged solid-state switch. Shooting in the dark here... but hopefully this helps!
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Jackson Oswalt
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Re: TMP Diagnosis

Post by Jackson Oswalt »

Hello!

First off, I apologize by the delayed response. As some of you may know, school has started back, limiting my free time to about 2 hours a day. The sad part is it'll only get worse.

Second, thanks again for all the help. Previously I've only known a small amount about the possible issues, but now I'm pretty confident the problem isn't at all what I thought.

Third, Considering it would be rather time consuming to make a separate reply to every comment (I would If I could), I'm going to try to answer all of the replys made after my last post. I'm going to start with the oldest, then move up to the most recent.

1. Jerry, you're probably right. As far as I know, the Robinair pump might only be getting me down to 300-400 microns. I really need to get a working TC, but they're all $40+.
2. Johan, there's a good chance you're right as well. According to Gooferking Science, the guy who used to own the same turbo (but in working condition) said that there didn't need to be a vacuum for the turbo to start. Second, I've seen the video of explaining the dead turbo. However, he explained how it died. It was an unrelated cause. Third, the connector between the pump and controller isn't just a bunch of alligator clips. It's the one designed specifically for the TMP.
3. John, I know. The Robinair sucks. I'm looking into diffusion pumps, but it is it possible I can use an ion pump instead? I've heard good things.
4. Dennis, first, the top rotor does spin freely. I think. It has the sound of a bearing *whooshing* around and of course stops after a bit because it's not being turned via the motor. There's no obvious resistance, but I don't really have the knowledge to tell. Thanks for the advice on not burning the fuses out. Generally, I don't let the fuse blow, but when I see the TMP do the same old thing I shut it off.
5. Rich, ha.......ha........ha.
6. Nick, thanks for the offer, but I don't think I'm ready for that yet. As I said, I think it spins freely. As for the rest of your post, I can tell you've got some expertise. Unfortunately, I'm only in middle school and have practically no idea what you mean. XD. I don't own an oscilloscope either, but if you can dumb it down for me it would be much appreciated.

Thanks all!
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John Futter
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Re: TMP Diagnosis

Post by John Futter »

Jackson
Forget the ion pump
they need 10 to the -4 millibar to start about twice as good a vacuum that your robinair can do
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