TLX temperature drops slowly

Don,

Thanks a lot!  Always excellent advices.

I haven't done anything with the hex screws today but I did get to feel the chamber housing.  Indeed I could slightly push down on the opposite side of the only visible hook.  I let the chamber stay that way and hope that it makes better contact with the thermoelectric modules.  The temperature did ramp down much faster.  I did not try to get it down below 10'C so not to risk the cooler.  Since I've pretty much decided to place a service call so I'll let the engineer to check it.  One of labs downstairs recommended a instrument service company who might charge lower rate for PM but it's probably better to pay the higher cost for factory service, I think.

One other reason I stopped the machine was  that I felt the smell from the air outlet changed today.  It might just be because that I removed the whole piece of smelly foam pad on the underside of the cover.  Since I don't know the full history of the machine until half year ago, I don't know if the  recent change of temperature control/vacuum performance has anything to do with low pump oil.  Could the diffusion pump fail if the oil level run too low or even dry?

Thanks,

LanceH

Lance, I really recommend that you try to adjust those screws BEFORE anyone actually tries to use the centrifuge again.  If they are broken, then they need to be replaced.  I wouldn't worry too much about the smells because that is a common problem with benchtop ultras.  Yes, the diffusion pump heating element can burn out if the oil level gets too low.  The bigger issue might be contamination of the diffusion pump oil with vacuum pump oil if things got tipped during the moving process.  By the way, who levelled the centrifuge and where was the level placed while the leveling was being performed?  It MUST be on the top of a rotor in the chamber.  Believe it or not, that can have an effect on the vacuum system performance too.

In reference to 3rd party service, some of the engineers working for these companies may be Beckman trained emgineers for this type of centrifuge.  If the engineer has not had formal benchtop ultracentrifuge trraining then I would not let them touch it.  There are profound differences between floor and benchtop ultras that has NOTHING to do with their relative size differential.  Anyone that says that there is no difference is lying throu their teeth and dangerosu to be working on your centriuge.  Of course, that's just my opinion.

Don

Don,

Thanks much again for the very informative comments. I leveled the unit myself with a level on top of the cover, and later on top of the steel plate inside the cover above the door. When I got the unit, I had a hard time deciding where Beckman might design a surface perfectly perpendicular to the spindle. The two places were the closest I could guess at that time. You are right, the top surface of a rotor made perfect sense to me.

On another note, I removed the white trim ring on the chamber and loosen the other 3 hex screws until the chamber had an even ~3/8 inch gap all around from the metal ring where the hex screws sit. This made the other 3 sides at similar height as the side with the hook intact. I could see the spacer when I turn the screws. However, the anchors were at lower positions so turning wouldn’t move them back to where they should be (i.e. the hooks would just hit the outside of the chamber). In fact, I wasn’t sure if the hooks were intact or broken as I wasn’t able to find an LED light to check them. I was thinking of keeping turning the 4 hex screws and see if the metal ring could be removed so I can readjust the hooks. Without knowing how the vacuum chamber was put together, I gave up the idea and turned the screws back to where they were. It is probably better to have a service engineer to take a look at it. I put a service sign on the machine until the chamber is adjusted back to where it should be. Thanks again.

LanceH

Lance,

    To be totally honest, the only level I ever used was a simple round bull's eye level that I purchased at Sear's.  It was just ver yconvenient, especially on the table top ultra rotors.

As to the chamber anchors, do not be afraid to turn them as they screws are counter intuitive as to how they adjust.  You should be able to rotate until the piece that hooks over the top of the refrigeration can is visible.  Then, you just hold the latch in place while turning the set screw back down.  the key point is to NOT overtighten the screws.  The screws should be slightly under the steel plate and if you look closely, the cavity in which the screws rest is tapered so you need to get the head down into the tapered area.  You should also seee two pretty good sized bolt heads along the right side of the top of the chamber.  They hold the door rails in place.  If you remove them both then you can slide the door completely out of the centrifuge so that you can clean the underside of the door.  This also allows you to have complete access to the o'ring on top of the chamber.  It's a good idea to carefully pull it out, clean the old vacuum grease off and reapply fresh high vacuum grease.  It is a very good idea to wear some kind of gloves while handling the o'ring and the vacuum grease.  It only took one time of not wearing gloves that resulted in my wiping my eyes after greasing the o'ring to convince me.  My eye burned for about an hour until the film of vacuum grease wore out of my eye.  Very painful.  Anyway, if there's anything else that I can assist you with then just get in touch with me.

Don

Don,

Bad news. 

We called a local scientific instrument service company who does a lot of maintenance for our institution to take a look at our unit.  They have service contracts with 2-3 Beckman TL/TLX in the other department so I thought they would be fine.  The tech came in, pulled out the pumps, and the forepump oil looked very clean.  No oil change was performed.  He did recommend changing the hose between the two pumps which he did (with a matching hose I supplied.)  The vacuum pulled down nicely, definitely went below 160 quickly and kept dropping.  Temperature was dropping steadily as well with a 50k spin.  I told him temperature seemed to drop slowly between 8 and 4.  He thought that might not be a big issue, especially the vacuum seemed to perform better after reolacing the hose.  He said the previous owner took good care of this unit.  The motor was quiet and speed sensor was stable.

Then I asked him about the chamber clamps.  He lowered the chamber with the hex screws and found that the other three clamps were broken.  He raised the chamber back to where it was, and moved the chamber around a bit to make good contact with the T/E units.  He then put the case back, and recommended repair of the clamps.  Everything was fine at that time.

A few hours after he left, I turned on the machine, the cooling did not work.  No heat, no cool.  Called the company and they sent him back the next day.  He checked and said that the T/E units failed and the TE board needs to be repaired/replaced.  I know things happed but this was hard to believe.  There are three T/E units on the board.  His boss said that maybe one or two failed earlier and the last one finally failed during the check up.  Now I’ll have to get the board repaired which could be expensive. 

It is not a good feeling that a reasonably well working unit suddenly requires repair.  However, I don’t think there was anything the tech did that could obviously cause the damage of the TE unit.  Not a very good day for me.

Lance H.

Lance,

    From what you just told me, the service tech IS responsible for what happened to the T?E board.  You don't mess with the chamber position and then just walk away WITHOUT ensuring good contact between the TEM's nad the chamber.  You can't do that without having the clamps properly tightened down and he should have known that.  I NEVER did anything with the chamber such as moving it around to make good contact.  The chamber tie downs are there to ensure chamber position AND proper contact between the chamber and the TEM's.  Again, he should know this if he is servicing the centrifuge.  At the very least, BEFORE he repositioned the chamber, it should have been removed, the modules and underside of the chamber cleaned, and recoated with thermal paste.  Then and only then should the chamber have been reinstalled and I would not have used ANY of the tie downs because it would place uneven pressure on only part of the chamber which could cause the apparent failure that you have experienced.  By the way, the board itself does not need to be replaced.  The modules can be easily replaced as there is no other circuitry on that board.  In fact, the process of replacing that board is a time consuming process that if not done properly can easily result in other issues popping up, especially relative to the vacuum.

   One other thing to check.  There is a circuit breaker on the power board underneath the control console.  It may have popped and if it did it was because of excessive current draw.  If I recall properly, the TEM's are set up in such a way that the failure of one will cause excess current draw in the others.  The design was set up such that the cooling or heating functions were not designed to work properly without all three modules being functional.  I will do a little more checking on this matter but in my opinion, I most definitely place a lot of the blame for this failure squarely on the service tech.  Proper service training results in proper servicing of the instruments and having a service manual and parts list does not mean that you have been trained.  This is probably the one major issue that I have with third party service is their lack of real service training.  Off of my soapbox now.  Get back to me if you have any other concerns and don't hesitate to give me a call at the number I previously provided.  By the way, where in the US are you located?

Don

Don,

Thanks much for taking your time to address my questions.  Before I talk to that company again, I'd like to make sure one thing about the circuit breaker -- If it pops, will it only affect the TE function or the whole unit?  In my case, only temperature control was affected.  Vacuum and spin worked normally.  That's before their second visit, now they've taken things apart.

Thanks,

LanceH 

Lance,

   Nice to finally talk to you real time.  The circuit breaker, if it needs to be reset, will not effect anything else so don't worry about resetting it.

Don

Don,

Likewise.

Thanks.

LanceH

Lance, No problem.  you can always give me a call about just about any Beckman centrifuge, spectrophotmeter or liquid scintillation counter.

Don