Hi,
I can not get a straight answer on this hope you guys can help me. I have a Marantz Receiver and want to replace some of the small value caps (like 1uf, 2.2uf, and 3.3uf) with film caps on my preamp board. The ones I am finding are rated at 250V.
So 2 questions:
1. the caps I am replacing are 25V and 50V rated. I have seen on a chart on the web that you could use a 250V rated cap in it's place, is this ok?
2. Can you put a film cap in an electrolytic cap location that is polar, the films are not marked + or- also can you use a film to replace a non polae elec. cap?
Thanks!
I can not get a straight answer on this hope you guys can help me. I have a Marantz Receiver and want to replace some of the small value caps (like 1uf, 2.2uf, and 3.3uf) with film caps on my preamp board. The ones I am finding are rated at 250V.
So 2 questions:
1. the caps I am replacing are 25V and 50V rated. I have seen on a chart on the web that you could use a 250V rated cap in it's place, is this ok?
2. Can you put a film cap in an electrolytic cap location that is polar, the films are not marked + or- also can you use a film to replace a non polae elec. cap?
Thanks!
The main problem is just the large physical size of the film caps vs e-caps. As was mentioned it's not really ideal to use long wires to connect them the the PCB. When doing this I like to use caps that have long enough leads to not have to use wire at all. Also the lower the voltage rating the smaller the film cap will be at the same uF rating. Generic mylars can be had in 100v.
You can also use "euro blocks" to allow easier swapping/rolling of capacitors. I did this on my cheap CDP a few years back: Modifying the NAD C521BEE You can see in post #2 how I got rid of the extender wires and just bent the leads themselves to fit into the euro blocks. They barely made it to them.
You can also use "euro blocks" to allow easier swapping/rolling of capacitors. I did this on my cheap CDP a few years back: Modifying the NAD C521BEE You can see in post #2 how I got rid of the extender wires and just bent the leads themselves to fit into the euro blocks. They barely made it to them.
I disagree. 20 year old electrolytic caps need to go. By that age about a fourth of them will be low value, unless super sealed long life grade (not found in consumer products, mostly). I don't know where you live, but lots of people stock 63v film caps here like newark.com and mouser.com. newark operates in about 50 countries as farnell.com. You can download the .pdf file from newark or mouser and figure out the size and lead length before you buy them. Some may be more suitable than others.
Patfont,
Check the Panasonic V series stacked metal film. Their 1uF/50 part is as small as a 1uF/50V aluminum electrolytic.
Digi-Key - P4537TB-ND (Manufacturer - ECQ-V1H105JL3)
datasheet:
ECQV(L)/(M) Series | Film Capacitors | Passive & Electromechanical | Panasonic Industrial Solutions Global
Ignore the naysayers in this thread
Check the Panasonic V series stacked metal film. Their 1uF/50 part is as small as a 1uF/50V aluminum electrolytic.
Digi-Key - P4537TB-ND (Manufacturer - ECQ-V1H105JL3)
datasheet:
ECQV(L)/(M) Series | Film Capacitors | Passive & Electromechanical | Panasonic Industrial Solutions Global
Ignore the naysayers in this thread
I know all about the theory
I do actually do this for a living......I think we are approaching this from different viewpoints here in that my point of "don't waste your time" comes from an opinion that an old Marantz receiver is not worth "improving"! You can't "make a silk purse out of a sows ear" as they say
If I follow the thread I'm assuming these are electrolytics that you want to replace? If so, I would use films of the same value to replace them, if they will fit. They do not need a bypass, just replacement. If they are electrolytics and old, then I would replace them.
I've replaced the electrolytics 3 times in my dynakit equipment manufactured 1961. In america's throw away import everything new every 6 months culture, this is heresy, repairing a device over 40 years. But then Europe had to restrict landfill access (ROHS) due to the PC displays that were poisoning their landfills with lead.My experience was that the electrolytics in the PC displays killed the switching power supplies in about a year. Now California has imposed a tax on new electronics to support special electronic waste collection. I feel I'm in the wave of the future- use what you've got, make it last. 3 times in a lifetime to replace electrolytics is too often. Replaceing computer displays every year because of cheaply sealed electrolytics is rediculously wasteful, no matter how cheap it is at the store. Film caps in my organ, and amps where available, should outlast me- at least 40 more years. And keep my trash can full of food waste, not consumer electronics. I'm building my skills, I should be able to deal with these PC switching power supplies this year or next- not with 1 year life caps again.
Your major problem is not degradation of the signal path capacitors though, it is the lifetime of supply reservoir and decoupling capacitors. Due to their values, these are electrolytic by nature as no-one has yet devised a capacitor type with large capacitance and high voltage that is not an electrolytic.
The usual reason to replace electrolytics in the signal path is to improve performance. Indeed, film caps are better for signal coupling, but in designs of this age the value of doing so is often outweighed by other factors such as pcb layout.
edit: Failure of supply capacitors in modern devices utilising SMPS's is another matter altogether - component quality vs price. Often such equipment uses cheap, poorly made (usually Chinese) capacitors which have insufficient spec for the job they are doing. The companies figure as long as they last the warranty period, good enough. This is just simply about corporate greed, not engineering.
The usual reason to replace electrolytics in the signal path is to improve performance. Indeed, film caps are better for signal coupling, but in designs of this age the value of doing so is often outweighed by other factors such as pcb layout.
edit: Failure of supply capacitors in modern devices utilising SMPS's is another matter altogether - component quality vs price. Often such equipment uses cheap, poorly made (usually Chinese) capacitors which have insufficient spec for the job they are doing. The companies figure as long as they last the warranty period, good enough. This is just simply about corporate greed, not engineering.
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Mr Patfont was working a receiver, replacing the 1,2,3,uf electrolytics. At 30 years, these little caps fuzz the sensitivity and sound. I know, I just recapped a 1979 transistor radio. Before-fuzz, no sensitivy, hum. After-great sensitivity, sharp, l'm listening right now & spent the all-NYC-tower memorial weekend listening to a 450 W high school FM station that just plays music. Bob Cordell would have a cat, I used some ceramic caps in the radio where film caps wouldn't fit. 40 more years I won't have to do those again. On my organ, I put 50 uf 470 VAC rated film caps instead of 50 uf 450 VDC electrolytics last year. Overkill, a little large, $15 each instead of $10 for unrated life electrolytics from sprague, but in my 71st year (a decade) I won't be crawling around in the floor replacing the electrolytics again. I'll be playing the organ, hopefully. Sometimes you have to use electrolytics because of size, but 1, 2, 3 were put in receivers in the seventies because of cost. Marantz was a "quality" brand, they lasted at least 10 years, mostly. Go for forty next time, you might live that long. It is hard as **** to not buy 500 hour electrolytic caps, except from newark. Mouser links to the pdf file, but most distributors don't even do that. Buy the cheapest ones, and buy some more next year, that is the *all-*art way.
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I can't think of any documentation on the subject offhand.
A film cap can be used pretty much anywhere an electrolytic is used although there will always be odd exceptions... for example a regulator decoupler may actually be better for stability with a cap possessing a little (normally unwanted) E.S.R. (equivalent series resistance). Also film caps get large very quickly, a 4.7 or 10uf at say 100v is BIG. That bulk can also make them prone to pick up stray interference from any radiated fields... so again... very circuit and application specific. Normally films would be used as input coupling caps and so on rather than an electrolytic.
A film cap can be used pretty much anywhere an electrolytic is used although there will always be odd exceptions... for example a regulator decoupler may actually be better for stability with a cap possessing a little (normally unwanted) E.S.R. (equivalent series resistance). Also film caps get large very quickly, a 4.7 or 10uf at say 100v is BIG. That bulk can also make them prone to pick up stray interference from any radiated fields... so again... very circuit and application specific. Normally films would be used as input coupling caps and so on rather than an electrolytic.
10 uf and below is where modern film caps will readily fit where 1970's 80's electrolytic caps were used. Look at the dimensions, don't get too big, to avoid the stray fields issue etc. I've violated that and got away with putting beer can sized film (50 uf, 1000 VDC) capacitors in a separate chassis than electrolytic cans (50,50 uf 450 VDC) because the beer cans wouldn't fit, but that was in an organ with no switcher supply or rf section to cause stray electromagnetic fields. complete metal shielding from RF is your friend if you are doing this. 1 uf, 2.2 , up to 10 uf film, usually fit right in, sometimes requiring standing up instead of laying down or something.
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