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Commentator

Join Date: Apr 2012
Location: Davao City, Philippines
Posts: 58
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How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/19/2012 11:09 AM

Hi to all experts, I posted before about the overheated motor of hemacrit machine.I discovered and I replaced the ball baring of the Motor as faulty.Now I discover also that the one of the resistor of the power board has became shorted, from 22000 k/ohms was became .2ohms cause it have color code of red,red,orange,gold.I just replace it.Now I just tested it this day.But I found out that I dont solve actually the problem.Cause it has another error of -2- displayed in LCD.Once I setted the rpm to 120 x100= 12000rpm with the maximum speed of the motor of 13000 rpm.

So, I concluded that maybe the error is the other load resistor and capacitor.My problem is how to locate this and if I locate I try to inquire in the Electronic Store it have no replacement of that capacitor .01 uf and .47uf 230 vac.Its a none polarized capacitor and it is a squared in form and have a color of gray.Actually this machine is ISO cause it is use in hospital Lab.

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Guru

Join Date: Mar 2007
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#1

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/19/2012 12:04 PM

I would contact the manufacturer for replacement parts...Is this a hematocrit centrifuge ?

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Commentator

Join Date: Apr 2012
Location: Davao City, Philippines
Posts: 58
Good Answers: 1
#4
In reply to #1

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/19/2012 2:36 PM

Thanks for that sir.I need the pictorial how to troubleshoot this.Hemacrit Centrifuge brand hettich model 210

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#8
In reply to #4

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/20/2012 11:59 PM
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Commentator

Join Date: Apr 2012
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#9
In reply to #8

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/22/2012 3:56 AM

Thanks for this sir.Its help me so much...Godbless

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#2

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/19/2012 12:43 PM

Check to see if you matched the color code of your resistor. A red, red, orange, gold color band represents 22K ohm @ 5% tolerance, not 22000 K as you mentioned. A 22000 K Ohm resistor would actually be 22 Megaohm, or red, red, blue, and some other color for the tolerance band.

As far as your capacitor is concerned, the description you gave sounds like an ordinary ceramic disk type. If you think it is damaged, make sure you identify it correctly because not all types are the same. Try using a search engine like Google to learn how to identify them. The paint or shrink wrap color on the outside of the capacitor has nothing to do with the functionality. It doesn't have to match.

Lastly, whatever it was that destroyed you resistor may have done other damage as well. I'm not sure replacing and testing one component at a time will result in a solution because each time you test the device with other bad components you may be causing damage to some of those you just replaced.

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Commentator

Join Date: Apr 2012
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#3
In reply to #2

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/19/2012 2:32 PM

ok thanks for that sir I know how to test that capacitor.But it just not like an ordinary ceramic caps.Ok just find it in google

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#5
In reply to #2

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/19/2012 11:37 PM

In all my years of administering Electronic Service have I ever come across such a change in value from that high to so low. Here is my point, this resistor color may have changed from gold to orange due to thermal issues over time. This resistor should be red red gold gold which is close to your resistance stated.I believe that this resistor test is correct regarding its reading and should not be changed. Most resistors when either partially burnt or open may show a near infinity reading, so 1ohm may read 100 ohms to over a 100k ohms when partially open and very rarely the other way around. As per the capacitor .....very simple to ID and change ...it is either shorted, open or dry.

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#6
In reply to #5

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/20/2012 4:37 AM

Yep. That's what I'm suspecting also. But I was thinking about originally purple color, (which is a by 10 divider) that describes the resistor as 0.22 Ohms, and makes some sense as a current limiter or a current sensing shunt. Resistor colors can be sometimes misleading if baked too hot, long enough. S.M.

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Join Date: Apr 2012
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#7
In reply to #5

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/20/2012 7:19 AM

Thanks sir your so good to correct my problem.But actually I used magnifier lense to assured that the color is correct and I observe that no burn indication or tried indication of the resistor its look good or condition.Actually I experience trouble of the sony tv could not sustain power.It can power up but in a moment of time it will turn off.When I check the resistor .01 uf of the primary it was open or shorted.Cause if I will check it using the analog voltmeter it will not deflect.Compare to the capacitor that I was bought once tested by voltmeter it will deflect so fast back to infinity. But this non polarize caps if i will tested using voltmeter it will not deflect.So, this is my problem I need another option so that I will confirm the problem of this unit.

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#10
In reply to #5

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/23/2012 4:50 PM

I have to agree that the color may have changed a little. I have seen resistors become shorts a few times but they were all black every time.

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Commentator

Join Date: Apr 2012
Location: Davao City, Philippines
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#11
In reply to #10

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

04/23/2012 9:08 PM

Yah...I'm favor of that but what I want is to recover the unit.So I will do the basis how to resolve this.So all the posible cause may be there.The other expert said that mechanical load.So I'm suspecting the load resistor and capacitor.So I got one the resistor that became shorted.Now the load caps but my problem there are no replacement here in Davao.Its a non polarize caps and square in form.0.01uf and 0.47 uf

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#12
In reply to #11

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

05/13/2012 2:03 PM

Your description of the capacitor and 230 VAC rating suggests it is a capacitor designed for 230 VAC power use. These usually have to meet stringent safety standards, they are usually metalised paper which self-heal after overvoltage breakdown. There should be no problem in getting an equivalent in Philippines.

It is probably one of two functions...

  1. A filtering capacitor at mains voltage. If it is this, its failure would not stop your equipment working, although it could be more vulnerable to mains spikes/radio frequency pickup. It would not have a series resistor of more than a few hundred of ohms for this purpose, often not having one.
  2. A ballast across an inductive motor load, it would take enough current briefly to latch a triac switch, before the inductive current becomes enough to latch. It would have a series resistor of higher value than 1/
  3. A low-loss ballast for feeding a low power DC supply to electronics direct off-line. It might be connected direct to an integrated circuit which has its own shunt regulator zener diode. It is usually essential to have a series resistor of 1000 ohm or more to stop high currents during mains voltage spikes, it is usually easy to trace the capacitor PCB track to the series resistor and IC or diode.

Can you identify which of these purposes the capacitor serves? There is no point in testing/replacing the capacitor if it is just for purpose 1/, it is not the cause of non-function of a unit. For 1/ and 3/ the voltage across the capacitor would be mains AC voltage - for 2/ it would be low if the motor was not working.

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#13
In reply to #11

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

05/13/2012 3:01 PM

Regarding capacitor test, since you obviously do not have a bridge to hand, perhaps only a voltmeter for AC, I suggest connecting to an AC mains voltage supply through a resistor of 470 ohm 10 watt.

Measure resistor with DC digital ohmmeter, the value R you read will be more accurate than the resistor tolerance which will be +/- 5% or 10%.

Check the capacitor is not short circuit with the ohmmeter before AC test. Connect capacitor and resistor in series to mains supply less than capacitor voltage rating.

Measure voltage across R, Vr, and voltage across capacitor C, Vc.

The reactance of the capacitor will be R x Vc/Vr.

Since reactance of capacitor is 1/(2 x pi x f x C), 0.47 microfarad at 60 Hz would be...

106 /(2 x 3.142 x 60 x 0.47) = 5643 ohms.

If you measured 475 ohms R, 10.9 volts Vr and 115 volts Vc, reactance would be...

475 x 115/10.9 = 5011 ohms.

Hence the capacitor value would be 0.47 x 5643/5011 = 0.53 microfarad.

If the capacitor is within its capacitance tolerance and does not get noticeably warm at rated voltage, it is probably functional and not the cause of unit failure.

Regards,

67model

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Commentator

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#15
In reply to #13

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

05/14/2012 8:15 AM

thanks for this sir...But I recheck again the all load caps.But It works, now I suspected the switching transistor and Ic positive controller...I replace now the short load resistor but the same problem sir...

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#14
In reply to #11

Re: How Can I Identify The Load Resistor And Capacitor As Faulty One?

05/13/2012 3:18 PM

Web address below looks like a source of similar capacitors in your area.

http://ph.mouser.com/Passive-Components/Capacitors/Film-Capacitors/Suppression-Film-Capacitors/_/N-5g7x/

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