Cap help

[MST246]

Hi Folks

I'm in need of some direction regarding cap replacement.After 12 trouble free years of bang and boom,my JBL E250P blew out C72 (6.8uf 100v non-polar blah,blah, blah) you guys know the deal here.

If understand correctly,guys are replacing this cap with a film cap.I will no doubt ask some stupid questions but it can't be helped.

After all the searching I'm getting bug eyed,a headache and pulling out whats left of my hair.

So,let the fun begin,is this what I'm looking for?

http://www.digikey.com/product-detai...F1685-ND/56410

Here come some stupid questions.

1. How to tell the polarized from non-polarized film caps,if they come both ways that is,I don't see anything in the specs
(warned you about the ?'s)

2. Does lead length and spacing matter here?

3. How close to the board should these be attached.

Thanks

[stj]

Re: Cap help

film caps arent polarised

[budm]

Re: Cap help

If you look at the old electrolytics bi-polar original cap, you will see that it is a lot smaller than the replacement film cap type, JBL uses the electrolytics type because it is cheaper but they do not last, that cap is part of the Class D power amplifier output filter cap.
You should also replace the C73 4.7uF at the same time. See service manual.
See if you have room to put those two new caps in place of the old one, just try to keep the lead length as short as possible and you will be fine.
JBL is not the only company that cheap out on these caps by using electrolytics in stead of film caps. I have seen so many failure of these caps in the output filter section of these Class D amplifiers.

[MST246]

Re: Cap help

If you look at the old electrolytics bi-polar original cap, you will see that it is a lot smaller than the replacement film cap type, JBL uses the electrolytics type because it is cheaper but they do not last, that cap is part of the Class D power amplifier output filter cap.
You should also replace the C73 4.7uF at the same time. See service manual.
See if you have room to put those two new caps in place of the old one, just try to keep the lead length as short as possible and you will be fine.
JBL is not the only company that cheap out on these caps by using electrolytics in stead of film caps. I have seen so many failure of these caps in the output filter section of these Class D amplifiers.

I was thinking about C73 also. I may just have to make room in the rubbery gunk the old caps sit in.Also is it true about C65 being incorrect 470uf that should be 47uf to stop chirp upon waking up? Is that even a problem?
Thanks to all for getting back.

[budm]

Re: Cap help

I do not see any TECH TIP in the service manual regarding to the cap values changed from what are shown in the diagram, may be you should contact JBL to see if they release any service bulletin for this model.

[MST246]

Re: Cap help

I do not see any TECH TIP in the service manual regarding to the cap values changed from what are shown in the diagram, may be you should contact JBL to see if they release any service bulletin for this model.

It's all over the net,but does not bother me.Right now trying to find film replacement for C73 4.7uf 50v but the filters show 100 and 250 for options,is ok to go higher on the volts?

[stj]

Re: Cap help

yes, if you can make it fit.

[budm]

Re: Cap help

It's all over the net,but does not bother me.Right now trying to find film replacement for C73 4.7uf 50v but the filters show 100 and 250 for options,is ok to go higher on the volts?

Is your chirping? To go 10 times less capacitance seems like a big change that I would think JBL will have service bulletin out.

[MST246]

Re: Cap help

Is your chirping? To go 10 times less capacitance seems like a big change that I would think JBL will have service bulletin out.

They all do it,but I think it's by design.Someone may have figured out a way to quiet it down.How about the other part of my question about the volts on the 4.7 C73.Thanks

[MST246]

Re: Cap help

Is your chirping? To go 10 times less capacitance seems like a big change that I would think JBL will have service bulletin out.

They all do it,but I think it's by design.Someone may have figured out a way to quiet it down.How about the other part of my question about the volts on the 4.7 C73.Thanks

[budm]

Re: Cap help

Higher Voltage is fine but the body size will increase with the higher Voltage rating.

[MST246]

Re: Cap help

Thanks for help guys,I may end up going with a known good brand elec for C73 just save one headache.

[jmonica]

Re: Cap help

I know this very helpful post is 3+ years old. Apparently Film type capacitors have gone down in price because unlike what was posted in terms of JBL being too chip to use Film type caps, film caps seem to be a LOT less expensive than the older type. I can buy 100 Film type capacitors for less than I can buy 1 Electrolytic capacitor with the same rating. It has me concerned now that I am not buying the right thing. Oh well what's the worst that can happen? Fry the rest of the Amp board? Its not working anyway. Electrocute myself? Can't find the upside to that one. Burn down my house and the houses surrounding mine? I'm insured.

[jmonica]

Re: Cap help

I know this very helpful post is 3+ years old. Apparently Film type capacitors have gone down in price because unlike what was posted in terms of JBL being too chip to use Film type caps, film caps seem to be a LOT less expensive than the older type. I can buy 100 Film type capacitors for less than I can buy 1 Electrolytic capacitor with the same rating. It has me concerned now that I am not buying the right thing. Oh well what's the worst that can happen? Fry the rest of the Amp board? Its not working anyway. Electrocute myself? Can't find the upside to that one. Burn down my house and the houses surrounding mine? I'm insured.

I'm an idiot. I thought Mylar Film capacitors were the type of film caps mentioned. I was wrong. The correct Film type caps ARE in fact way more expensive. That why morons like me shouldn't comment on well, anything.

[stj]

Re: Cap help

polypropylene film.

[redwire]

Re: Cap help

Polypropylene are hard to find in low voltage. They are usually >250V and physically big, and ~4X the cost of Polyester/Mylar.
Anyone know what this cap does in the JBL? Crossover?