Really dumb question

Serendipity

When replacing electrolytic capacitors in audio/video gear, is it okay to use capacitors of a higher voltage capacity (but same uF value)?

madmax

Yes.
madmax

rskarvan

I think the printed voltage capacity is more/less a maximum value. So, going higher means that the capacitor is rated for "up to" this voltage rating. However, the tolerance of the capacitor value may change.

"There is a voltage dependency that is in addition to both the initial tolerance and the temperature coefficient. For some types, operating at full rated voltage reduces the capacitance to less than half of the zero voltage capacitance."

In transient circuits, everything affects everything. The question really becomes, "will the difference be significant". The answer is probably... "I hope so... but, in a good way". Whether or not that is the case depends on your ears.

http://wiki.xtronics.com/index.php/Capacitor_codes

Serendipity

Thanks.

So I will have no problem replacing the capacitors in my VCR?

Systems

appadv wrote: »

Thanks.

So I will have no problem replacing the capacitors in my VCR and projector this way?

It will not harm the equipment, right?

Higher voltage is fine and be sure to install them with the correct polarity or you will have a mini bomb when voltage is applied.

treitz3

appadv wrote: »

It will not harm the equipment, right?

No, it will not.

Serendipity

GV#27 wrote: »

Higher voltage is fine and be sure to install them with the correct polarity or you will have a mini bomb when voltage is applied.

Thanks, I already replaced the video head (drum) in my VCR and it went fairly easily.

Now, this has me puzzled - how do I replace surface mount components? I found some shorted capacitors (on a few pieces of dead equipment) that are of the surface mount type.

treitz3

Hehe. You don't. One exception and you have to have one HELL of a steady hand, fine tipped soldering iron and experience with surface mounted components. Other than that, replace the board.

Surface mounted boards are pre-tinned, components are put into place, then they are oven baked....not to be repaired, just replaced. FYI.

Serendipity

treitz3 wrote: »

Hehe. You don't. One exception and you have to have one HELL of a steady hand, fine tipped soldering iron and experience with surface mounted components. Other than that, replace the board.

Surface mounted boards are pre-tinned, components are put into place, then they are oven baked....not to be repaired, just replaced. FYI.

Nice, however the board that I am trying to replace (with the failed capacitors on it) costs over $1500 from the manufacturer. I already checked and it was VERY expensive.

On a positive note, I've had good success with VCR repairs

Serendipity

So is there any way that I can repair it myself?

Systems

appadv wrote: »

So is there any way that I can repair it myself?

Maybe:)as Treitz3 suggested you will need a fine tip iron, also a magnifying glass will be of help.SMD electrolytic caps have a solder tab on each side at the bottom of its case. You can use solder wick or solder sucker and carefully desolder the old part.Dont apply too much heat so as to not lift or damage the traces.If you succeed then solder in the replacement.

Serendipity

Thanks for all your help guys!

I'm not sure if I can do the surface mount stuff yet as the board I am working with is multiple-layered.

Serendipity

GV#27 wrote: »

Higher voltage is fine and be sure to install them with the correct polarity or you will have a mini bomb when voltage is applied.

When you say mini bomb, how bad is that?

I know capacitors are marked on their negative terminal, so I'll be sure to install them the same way the original capacitors were done.

treitz3

appadv wrote: »

When you say mini bomb, how bad is that?

Depending on the current, voltage and capacitance, small firecracker to deadly. This is an area you don't want to make a mistake with.

Serendipity

treitz3 wrote: »

Depending on the current, voltage and capacitance, small firecracker to deadly. This is an area you don't want to make a mistake with.

Wow, I'll be sure to install them correctly.

hearingimpared

I didn't think that was such a dumb question.

Serendipity

hearingimpared wrote: »

I didn't think that was such a dumb question.

Haha, I don't know much about electronics repair

Systems

Can I donate a VCR to keep things safer?

Systems

appadv wrote: »

When you say mini bomb, how bad is that?

I work as a QC tech for an electronics manufacturer and have had a few smaller ones blow on my bench and I can assure you that without my safety glasses I would have had eye damage.My glasses were covered in electrolyte fluid and part of the metal casing hit them as well.:eek: Ofcourse I should have caught the error on the visual inspection before powering up:o

SolidSqual

This question sounds way too smart to be dumb . . .

madmax

The best way to remove SMT components like capacitors and resistors is with two irons if you have them. However, since the parts are bad anyway don't worry too much, just go back and forth quickly on the two connections until it comes loose. You are trying to get it hot enough on one side to stay melted until you get to the other side.

Serendipity

madmax wrote: »

The best way to remove SMT components like capacitors and resistors is with two irons if you have them. However, since the parts are bad anyway don't worry too much, just go back and forth quickly on the two connections until it comes loose. You are trying to get it hot enough on one side to stay melted until you get to the other side.

Thanks, seems difficult though...

Serendipity

All in all, I am happy that replacing the caps made a difference.