Discussion Category:  Centrifuge

Transformer humming, then unit shut down at 1500rpm

Hi, the calibration field service told me the transnformer need to be replace. Is this true? The odometer on this unit is 5991437 x1000 rev is it time to put it away?  thanks,

Trong

 

 

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trong.ha
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dpkleessr

Trong, Almost all L8M centrifuge transformers hummed. It was only a question of how bad as to requiring one to be replaced. It is difficult to know what to tell you as to whether or not it needs to be replaced via an email. There is absolutely NO reason to stop using your centrifuge based upon the usage you listed. What other symptoms did the centrifuge exhibit and what are the qualifications of the "calibration engineer" to make the suggestion of replacing the transformer?

Don

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trong.ha

Hi Don, the transformer seems to be getting weaker it hummed 2 times then it shuts off the power, circuit breaker tripped, no error message.  I had Tim from BTS (a former Beckman fied service Engineer) came in to calibrate last week and he suggest the problem is the Transformer.  I have a lot of spare board should i try to replace the boards first?

Trong

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trong.ha

I replaced board #8 (power board) and that fixed the humming transformer and power shut down problem, but right now i have problem with vacuum keep going at 900 and 700.  i will check my previous posted for vacuum problem.  thank for your advise that it's not the transformer.

Trong

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dpkleessr

Trong, If you are not pulling below 700 microns then you have a serious vacuum leak that should not be difficult to find. When was the last time you changed the vacuum pump oil and vacuum hose? One easy thing to do that was a frequent problem with vacuum readout problems has to do with the connector on the vacuum sensor. Unplug the connector and CAREFULLY insert a point instrument to tighten up the spacing between the prongs of each pin opening. Sometimes just slowing pulling out on the connector can cause a very sudden change in the reading as the issue is all about getting good contact again between the sensor's pins and the connector pins. Start from there and get back to me and I'm glad you did not head down the road of replacing that transformer. Once again long term field experience saves the day.

Don

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trong.ha

Thanks Don, i did checked puling the prongs, but the effective vacuum leak is scrap out, clean all the vacuum grease underneathe the lid. now i got fixed, it's pulling to 200 micron in 6 minutes and reach 40000rpm in 7 minutes with rotor 45Ti.  after cleanning the lid, the vacuum pulling straight to  the maximum of 150 micron could nt go lower than that. maybe there is still a small leaks or need new oil.  Does it need to be going lower? Oh, the run has stop the vacuum is still pulling to 70 micron.  Thanks, i've learned and fixed alot of centrifuge problem from you over the years.

Trong

 

 

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dpkleessr
Trong, Carefully check to see if your diffision pump is getting hot because the centrifuge should get down to 1 micron within 20 minutes and at any vacuum greater than 100 microns means that you do not have an accurate temperature reading. Don
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trong.ha

Great! i ran a 20 minutes run and vacuum went down to 1 micron. case closed.

Trong

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dpkleessr
Trong, Great news and happy to help. Don
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