They're 200v 390uf.

Hmmm... in that case, if it were me I'd opt for the 450 volt part, just to be safe. Or "probably" safe...

 

Hmmm... in that case, if it were me I'd opt for the 450 volt part, just to be safe. Or "probably" safe...

I will go for the 630V but I have to measure the size correctly to make sure it will fit. I will report back. Thanks for your time sir.

 

You're welcome.

 

.It says it is an IN-CIRCUIT tester. Does that mean it will also test a component by itself?

The "in circuit" comment means it runs its test signal below 0.65V and thus shouldn't turn on any nearby semiconductors. The measurement looks at how low the test signal gets pulled down by the cap. Lower voltage equals lower ESR.

 

Hi all,

Is this normal reading for a 150nf capacitor ? Please see the photo.

Consult the manufacturer's data sheet.

 

Hi all,

Is this normal reading for a 150nf capacitor ? Please see the photo.

The MESR-100 meter doesn't measure the true ESR of a capacitor. Like many of these low cost ESR meters, it measures the impedance magnitude.

Here's a description of 3 methods of measuring ESR of a capacitor: http://www.midwestdevices.com/pdfs/Tnote3.pdf

The MESR-100 is using method #1 described in that tech note. This technique can't be used for capacitors whose reactance at the measurement frequency is substantially greater than the resistive part of the impedance (ESR in other words).

At 100 kHz, the reactance of a 150 nF capacitor is a little more than 10 ohms, and that's quite a bit more than the ESR should be.

Here's a measurement of a mylar 150 nF capacitor done on an impedance analyzer. The analyzer can show the impedance magnitude (Z) and separate it into the reactance (X) and resistance (Rs, which is the ESR):



Mylar is one of the worst (but cheap) plastic film dielectrics. You can see that the ESR of this capacitor is .321 ohms, but the reactance is -10.774 ohms. The reactance and resistance combine vectorially to give an impedance magnitude of 10.779 ohms. Your MESR-100 is measuring an impedance magnitude of 10.23 ohms, which is what one would expect for a 150 nF capacitor, but this is not the ESR.

Here's a measurement of a polypropylene capacitor under the same conditions:



Notice how much lower the ESR is; only 11.27 milliohms. So-called ESR meters using method 1 as described in the above referenced tech note can't measure the ESR of capacitors as small as 150 nF. They do OK on capacitors greater than 10 uF.

So, you can't really tell anything about your capacitor's ESR with the MESR-100.

But there is a small, low cost meter that can do the job and it costs little more then the MESR-100. It has come on the market in the last few years and can be had for around $100: http://www.ebay.com/itm/DER-EE-DE-5...677109?hash=item211bffe9b5:g:pIQAAOSwpDdVbt9a

 

Do not plug it in with that capacitor missing. 400V is very likely what is required in that part of that circuit. A 250V rated one will not last long.

 

@The Electrician Very cool post. Puts the issues in sharp relief.

 

Is this normal reading for a 150nf capacitor ?

depends on how it is measured.

 

@The Electrician - what gear are you using to take your readings?

Thanks

 

@The Electrician - what gear are you using to take your readings?

Thanks

https://www.hioki.com/en/products/detail/?product_key=5539

It's very handy if your job involves designing magnetics for switchers.

 

https://www.hioki.com/en/products/detail/?product_key=5539

It's very handy if your job involves designing magnetics for switchers.

I'd run right out and buy one, except it costs as much as half a car. If you need it you need it.

 

I'd run right out and buy one, except it costs as much as half a car. If you need it you need it.

It's a lot easier to convince your boss to buy the Hioki than this: http://www.keysight.com/en/pd-24051...50-120-mhz?nid=-33831.1089074.00&cc=US&lc=eng

or this: http://www.ebay.com/itm/HP-Agilent-...678933?hash=item20ff917f95:g:DHkAAOxybi9Rbrff

 

The one we had at AB cost $89,000 so I'm familiar with the eyebrow raising prices.

 

I now have another suspect, and is the operational amp or op-amp module number JRC 072B 8014G since the audio output is very low

You can buy AD8512 or TL072. But you can you tell us the model number for this class- D amp ?

 

Ok, so no chance to get a service manual. Have you check the output MOSFET's or the driver chip?

 

https://www.hioki.com/en/products/detail/?product_key=5539

Wow, I would love to have one of these. Too many digits in the price for my shallow pockets.