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avatar: bberg7794
bberg7794
15 posts
Replied to bberg7794's post on February 1st, 2016

Hi all,

Among other duties, I am responsible for the care of a Beckman TL-100 Ultra.  Recently, we have experienced a persistent "Drive" error.  The machine will spin up to around 50,000 rpm, hang there for a second or two, then shut down showing and annunciating the drive error.  Both cooling fans are working well.  The baffles that direct the cooling air against the fins could be  in better condition-most of the foam has deteriorated away leaving a gap between the edge of the fins and baffles.

I have three main questions at this time:

1) How does one check/change the drive oil?  I have removed the drive assembly from the armor chamber and separated the top and bottom finned units (via the lord mounts).  All parts are on my bench at this time.  The bottom unit, containing the drive motor, can be separated further via three allen screws.  Is this necessary for replacing the drive oil?  There is a bolt with a 5/8" head on the bottom of this unit.  Does this hold the motor in place?  Are the black rubber(?) strips across the fins for sound deadening?  Can they be reused if the upper and lower portion need separating?

2) What is the white grease that is used on the pads of the triangular shaped board that the aluminum chamber sits on?  Can this grease be purchased?

3) Is there a good replacement for the foam that has deteriorated away from the baffles and other areas of this machine?

I have gotten to know this machine fairly well in the last three years.  I have had to replace the shock mounts twice, but I did this "in situ" without removing the motor from the armored housings.  I also have changed the mechanical pump oil and diffusion pump oil, replaced the hose between the diffusion and vacuum pumps and also replaced the o-rings on the rigid vacuum pipe between the chamber and diffusion pump.  I had to repair one of the pins from the speed sensor to the triangular shaped board under the aluminum chamber, which was giving some erroneous speed errors.  This machine has kept me busy, but seems pretty repairable and robust-so far, so good for a unit of this vintage.

avatar: dpkleessr
dpkleessr
1116 posts
Replied to bberg7794's post on February 2nd, 2016

Well, since you already have the drive out of the centrifuge you have done most of the work already. First, why do you believe that you need to change the drive oil? Unless you have been seeing LOTS of oil in the chamber you should not worry about doing this. The oil is a special formulation of Mobil 1 synthetic oil so it should last a very long time and just looking at the oil you would not be able to tell if it is good or bad by the color as it is naturally dark in color. Under NO circumstances do you want to remove the drive spindle from the drive assembly. Unless you have the correct tools, there is no easy way or more importantly, a correct way to reinstall the spindle. You drain the oil by removing the nut you observed on the bottom of the drive. That nut actually has a small magnet embedded in it to hang on to any metal particles that might be thrown off of the drive through normal wear and tear. Oil is replaced in the drive by getting the drive oil through Beckman. The bottle comes with a nozzle that fits down into the holes on top of the drive around the spindle. DO NOT overfill the drive. The rubber drive mounts should be replaced if they have not been before or if they appear to be dried out and cracked. The sticky rubber on the outside of the drive housing helps keep the drive centered and snug in the vacuum chamber so it should be put back in place if you have removed it. The bellows assembly, the black rubber piece with metal rings on both sides and a spring in the middle should also be examined for cracks as that was a problem area over the years. If the rubber bellows does not have white rings on the outside then it is an original bellows and it should also be replaced.

Next, the white grease is actually thermal paste and it absolutely is required. Otherwise you will burn out the peltier modules. You only need a VERY thin coating on the top of the TEM's (Thermo Electric Modules) but the entire surface of each module must be coated. You can buy the paste either on line or from an electronic parts store that might be around. Be very careful with the paste because if you use your bare fingers to apply it and accidentally wipe your eye it will burn like hell.

As to the foam underneath the top cover, peal it off and throw it away because it really did not do much good even when it was brand new with noise abatement.

Finally, the actual problem the centrifuge is having can be the result of several issues. First, there are 4 LED's that can be examined with the top cover off that can help with the troubleshooting.

An overheated drive can cause this problem so ensure that the two cooling fans are running at high speed on the side of air intake and that the intake area is not blocked in any way. This lights up DS804 only.

If the centrifuge determines that it is not controlling the speed properly then you get DS803 on.

If the crowbar circuit thinks there is too much current being drawn then you get DS803 and DS804 on. If this LED is on then also check to see if DS302 is on located on the speed control board in the chassis.

IF DS301 is on this would indicate faulty drive current control.

The other issue is if the drive damper is not disengaged properly which turns on DS802.

Since you have disassembled the centrifuge as far as you have, you do need to verify the vacuum performance after you reassemble it. This is done by using S604 on the Interface board. The vacuum reading will show up in the temperature display. Make sure that you clean and grease the drive and chamber o'rings as you are reassembling the centrifuge and just like the thermal paste, DO NOT get any of the high vacuum grease in your eyes. You will need an ER visit if you do.

Get back to me when you have more information and we will go from there.

Don

avatar: bberg7794
bberg7794
15 posts
Replied to bberg7794's post on February 3rd, 2016

Hi Don,

I want to replace the drive oil for a couple reasons.  We know this oil is partially responsible for cooling the drive motor and I don't know when it was last changed, if ever.  This machine has not seen a factory technician since 06/2003.  The fans seem to be working well-no obstructions, turning in the correct direction and strong pull. My thinking is that changing this oil would eliminate one possibility for the 'drive' error and for the small effort involved would be prudent in our case.

I carefully inspected the bellows with a bright light and they appear to be in great shape-thank you for your description of them.

I should also mention this machine sees very intermittant use (sits for months, then is run for a week or two before months of sitting again).

I am waiting for a replacement speed sensor and the drive oil.  Once I get the motor reassembled and reinstalled, I will try running the machine and get back to you with what led's I see.

Thank you so much!

Brian


PS.  For some reason, your reply came to my email via LabWrence, but I do not see your reply here.  IT????

avatar: dpkleessr
dpkleessr
1116 posts
Replied to bberg7794's post on February 3rd, 2016

Brian, One thing that all users should do before using the centrifuge after prolonged down time is shut the door with the power on and let the vacuum run for around an hour. The older vacuum configuration typically needs this long to remove all of the dissolved gases from the oils and when it is actually time to do the run, the vacuum should pull down very rapidly and allow the run to proceed. If not, you may get a roller coaster effect where the rotor speeds up then slows down as the vacuum goes above the minimum vacuum level until everything gets heated up and out gasses.

Changing the oil is not a bad thing, especially if it has been at least 12 years since it was last serviced but the primary cooling of the drive is from the airflow over it. That is why ensuring free flow of air by the fans is so critical. Generally speaking, however, I never had a drive issue that could be solved by simply changing the oil. Hopefully this will take care of your problem but I won't be holding my breath about it doing that.

As to the drive bellows, unless it actually has the white marks I talked about, you really should replace it. You can have hairline cracks that are not detectable while it is under compression but will eventually cause problems. Just trying to save you a future problem where you have to remove the drive again.

Let me know how things go in your efforts to repair it.

Don

avatar: bberg7794
bberg7794
15 posts
Replied to dpkleessr's post on February 3rd, 2016

Hi Don,

Thanks for the tip about running the machine for an hour before attempting a spin.  I will get with the PI and other users and discuss this with each of them and also make a reminder sign for the machine.  Some of the users have become frustrated with intermittant 'spd' messages and have cycled the power-or unplugged altogether.  I explained the part in the instruction manual about letting the machine run for 20 min. with this error-then the error clears nicely.

The bellows I have is an old one.  Do you know the p/n I need?

Are there any known problems with the sensor on the drive assembly (says "Stemco" on it and has two purple wires)?  I presume this is the temp. sensor for the drive.  When I ohm it out, there is almost no resistance, but I don't know if that means anything.

Brian

avatar: dpkleessr
dpkleessr
1116 posts
Replied to bberg7794's post on February 3rd, 2016

Brian, I am visiting family back in PA so I do not have access to part numbers available to me but I will check when I get home or call one of my former coworkers to get it.  The tach sensor on the TL100's have been problematic over the years.  The other thing is the sensor has to be positioned properly and this was done by  using a special spacing tool.  Failure to have the correct spacing can give you a "SPD" diagnostic.

The sensor on the drive is something else that I will have to look into when I get home on Saturday.  Thermostats by their very nature are usually a dead short and only open up to signal that there is a problem so that is probably not an issue.

Don

avatar: bberg7794
bberg7794
15 posts
Replied to dpkleessr's post on February 10th, 2016

Hi Don,  Hope you had a wonderful time in PA.

I have a new stumbling block.  I ordered a speed sensor (tach pickup p/n: 346468) and received it last week.  It is different from the one on our machine-wish I could post a picture.  The one Beckman sent is a two-piece unit with four wires (red, black, yellow, white) and an opening for the drive shaft slightly larger than 1/4". 

The tach pickup sensor previously installed on our machine contains two parts, both living just beneath the rotor mount: the top unit is one-piece with a slit and a 3/4" opening, allowing one to slide it over the rotor mount on the shaft.  It has three wires (red, black, yellow) and slides over the rotor mount attaching to a second piece containing the white wire.  Both parts are indexed so the tach pickup and mount(?) maintain the same angular relationship to each other.  The second part is also one-piece with a slit and attaches to a ridge on the metal sleeve that the bellows go over.  I assume this second part to which the first part mounts maintains the critical spacing necessary to allow the sensor to work accurately.  The two parts do not contain a part number that I can see (I haven't removed the bottom mount).

Does this sound familiar to you?

I sent the company a photo of both units side by side.  The company claims they know nothing about the unit I have and are also not forthcoming on issuing an RMA.  This makes me hesitant to order a new bellows from them, but what choice do I have?  I don't seem to have much luck receiving help from them-very different from my previous aviation career.

Brian

 

avatar: dpkleessr
dpkleessr
1116 posts
Replied to bberg7794's post on February 10th, 2016

There are many differences between the old original TL100 and all subsequent versions and it appears that you received the later version tach pickoff even though you have the correct part number for the device you need. Beckman should either exchange it if they have one of the original devices and quite frankly, that may be the biggest problem of all. The TL100 was obsoleted well over 10 years ago and service parts became a real issue. Beckman also stopped selling service agreements on them and further prevented us from servicing the TL100 because of the parts issue. Of course, those of us in the field generally ignored such things but I believe that you may now be at a dead end on this centrifuge unless you can find someone with service parts for it. The TACH sensor was an extremely low failure item and your issue may be more of spacing of the TACH sensor than an outright failure. That is why we used a spacer tool to properly position the sensor vertically. The correct spacing is 0.040". The other white ring piece that sits underneath the pickoff is actually the temperature sensor so it has nothing to do with your problem. If it is removed, however, make sure that you put heatsink paste upon it prior to reinstallation.

You need to tell Beckman that the part number you actually received was 359742 and feel free to tell them that I gave you the information. Also, the bellows part number is 343573.

That's the best I can do at this point to help you out but feel free to get back with me when you have more information. I may also be able to help you out getting the part returned for credit through some of my friends that still work there.

Don

avatar: bberg7794
bberg7794
15 posts
Replied to dpkleessr's post on February 11th, 2016

Our original tach sensor had a broken pin to the black wire some time ago.  I did not have any pins this small, so I used a micro drill to remove as much remaining wire as possible and soldered the end of the black wire into the old pin.  Upon removal this time, the black wire and pin have again separated and the black wire also is smashed pretty thin in one location.  I think the pin and wire have been making intermittant contact.  The wire/connector condition and the fact that this machine has had at least three broken lord mounts is why I ordered a new sensor.

Today I removed the temp sensor.  It appears the part Beckman sent me may work.  After measuring everything with my calipers, it looks like it will mount exactly where the former temp sensor lived and take up the same amount of space as the original tach/temp. combination unit.

The old temp sensor has a miniature spring attached to a (carbon?) foot that bears against the metal sleeve.  The new sensor also has a similar miniature spring, but there is nothing to bear against the metal sleeve-no foot.  I don't think this spring can even contact anything.  Is it measuring temperature by varying tension?

I presume .040" is measured from the bottom of an installed rotor?

Being able to use the part they sent me would be the best possible outcome, provided it works.  Do you think I should install it and give it a shot?

Brian

 

avatar: dpkleessr
dpkleessr
1116 posts
Replied to bberg7794's post on February 11th, 2016

Brian, The TACH pickoffs are NOT interchangeable because of differences in the drive assemblies themselves.  The spring that you are referring to is actually the IMBALANCE sensor and not the temperature sensor.  Again, the metal ring that is held in place by four hex screws on the bottom of the chamber is the temperature sensor.  The TACH sensor spacing is measured from the bottom of the rotor although getting a feeler gauge under the rotor parallel to the pickoff to check the spacing is problematic at best.  That is why all service engineers carried spacing tools for the different versions of benchtop ultracentrifuges.

Don

avatar: bberg7794
bberg7794
15 posts
Replied to dpkleessr's post on March 18th, 2016

Hello Don,

Well, I got busy with a couple student projects in the shop for a while, but finally was able to return to the Beckman.

First, I drained the drive oil carefully into a graduated cylinder and found it had approximately 65 cc's of oil in the drive.  I was able to fill the drive with 90 cc's of new oil using the nozzle provided.  Thanks for the advice.

Next, the bellows I removed self-destructed on my workbench due to the spring pressure.  I ended up ordering a new bellows and received a replacement from Beckman, but it appears to be one of the old type (no white marks).  Due to folks wishing to use the machine, I installed it with fresh vacuum grease top and bottom.

I replaced all three Lord mounts on the bench this time, so each is now installed without any unwanted twist, something I could not assure when replacing them in situ.

The three o-rings from the armor ring and bottom beneath the chamber were all cleaned and coated in vacuum grease.

I coated the TEM's with thermal paste as suggested.

The temp sensor at the bottom of the chamber had a couple allen screws that would not torque up.  The threads in the chamber were stripped, but I repaired them using two very small Heli-coils.  Then the temp sensor received its coating of thermal paste and was installed.

Next the chamber went in and I installed the tach sensor.  Apparently I didn't describe things well enough, but it does appear to be correct even though there were a couple small differences.  What convinced me was that the hall effect sensors had the same part numbers between the old and new parts.

After getting everything back together, except the cover, I made a number of test runs.  I initially had a couple vacuum issues and saw the roller coaster effect you mentioned.  This prompted me to clean the o-ring under the door again, which I haden't done on this go around.  Now, the vacuum pulls down in around 1 min. after the door has been opened, and I have made six successful runs of 20 min. each at 100K and 4C.  The machine now accelerates smoothly up to speed and I no longer see any intermittant "SPD" messages nor any "Drive" messages either.

I hope this is it for a while-thank you so much for all your help.

Brian