Caps

[mike9h29]

Hello,

I have some benq monitors that does not work, and that I always wanted to fix.

After reading on the internet, I found that most of the time, replacing Transistors, Caps & Fuses will fix the problem with them.

So, I purchased some caps from Ebay.

I dont know their brand, but some sad low ESR.

Will cheap caps from ebay work with TFTs pls?

If no, which caps shall I buy please?

Thanks

Mario

[digge]

Re: Caps

Depends entirely on what you bought and what was originally there that you are replacing. So look up all the values and if you can brand and series of the original caps as well as on the ones you bought. Even better would be a picture of the board/caps.

[mike9h29]

Re: Caps

I`ve ordered caps according to the original (old caps) values. but did`nt know about brands.

does brand make a difference please?

[sofTest]

Re: Caps

Yes, brand does matter. Recommend you have a look under the FAQs found at the top of the forum.

[mike9h29]

Re: Caps

What I wanted to ask is:

let say that the monitor caps are elite 470uf 35v. I go on ebay and buy unbranded 470uf 35v caps. will they work please? or do I need to check other things?

also, are non-polarised capacitors good?

Sorry for asking again, but maybe my question was not so clear.

Thanks in advance for your kind support to some one new like me!

Mario

[steve2]

Re: Caps

They will probabaly work, at least for a while, depending on brand. aside from matching the uf and v, match the temperature. If they are 85c then put 85c or 105c in. Do not lower the voltage or temp rating (you can go higher, but the physical size may change where it won't fit right). If it is a low esr , then use a low esr cap. If it is general purpose, then use general purpose. The datasheet will give the details. Non-Polarized go where a non polarized came out of, but not to replace a polarized one.

[sofTest]

Re: Caps

When selecting capacitors for a circuit, the circuit manufacturer has to find capacitors with certain characteristics for that application. That's why capacitor manufacturers has many series of capacitors. Ideally, you will want the replacements to have the same characteristics as the one you are replacing.

When you buy unbranded capacitors on eBay, you will not find datasheets that you check against the characteristics of the capacitors you want to replace. Experience tells us also that unbranded capacitors are of poor quality, and for most applications we deal with here, not with the characteristics that will work. We have seen numerous examples here in forum of people bought unbranded capacitors, and come here asking why the circuit does not work. That's easily explained by the quality of the capacitors, performing so badly that they for all practical purposes are defective as new (for that application).

Also, on eBay there are a lot of fake branded (in the recommended list) capacitors, as bad as the unbranded. You need to be very careful buying capacitors on eBay. If you don't have an ESR-meter, so you can verify the capacitors, eBay is not a good source of capacitors. In the FAQs, recommended manufacturers and series of capacitors are listed. You will not find anyone here in the forum recommending anything else.

So, when replacing capacitors you need to:
1. Look up the datasheet for the old ones
2. Find new capacitors with same/similar or better characteristics (ripple and ESR/impedance)
or;
list up manufacturer, series, uF and voltage for the old ones, and ask for advice for new ones here in the forum.

Non-polarised capacitors are for most applications we deal with in this forum, not suitable.

[mike9h29]

Re: Caps

Thanks steve2 & sofTest! I really appreciate your great answers to my question!

Whats the best caps (brand, esr) should I buy to fix Benq TFTs please? or they use different caps depending on the model?

Thanks again.

Mario

[steve2]

Re: Caps

You will need to post what brand caps are in it, plus the uf, v, diameter and height in mm, and the series (so the size, esr and ripple can be gotten from datasheet) on the side of old caps. A picture if possible to see if there is room for larger caps or if they need to remain same size.