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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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SMD capacitors
I started working with the SMD parts a year or so ago. I decided to stock up on some from ebay where you get strips of 10 each of about 50 valuse for a couple of bucks. In this assortment were some 2.2 and 10 uF capacitors. For the most part capacitors I am used to working with valuse round 1 uF and up are usually polarity sensitive. Are the the large values non polar like the smaler values ? I have not had time to look at them under my microscope to see if they look different. |
#2
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SMD capacitors
On Monday, August 28, 2017 at 4:08:16 PM UTC-4, Ralph Mowery wrote:
I started working with the SMD parts a year or so ago. I decided to stock up on some from ebay where you get strips of 10 each of about 50 valuse for a couple of bucks. In this assortment were some 2.2 and 10 uF capacitors. For the most part capacitors I am used to working with valuse round 1 uF and up are usually polarity sensitive. Are the the large values non polar like the smaler values ? I have not had time to look at them under my microscope to see if they look different. I'm not sure I understand your question. Whether a cap is polarized or not depends on the type cap. Tant's and Al are polarized (in general) and ceramics aren't. George H. |
#3
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SMD capacitors
On 28/08/2017 21:08, Ralph Mowery wrote:
I started working with the SMD parts a year or so ago. I decided to stock up on some from ebay where you get strips of 10 each of about 50 valuse for a couple of bucks. In this assortment were some 2.2 and 10 uF capacitors. For the most part capacitors I am used to working with valuse round 1 uF and up are usually polarity sensitive. Are the the large values non polar like the smaler values ? I have not had time to look at them under my microscope to see if they look different. If they are MLCC, the capacity can be quite high maybe even 10uF these days, but very low V and a susceptibility to metal migration it PbF soldering temp requirement fracture the ceramic at laying |
#4
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SMD capacitors
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#6
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SMD capacitors
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#7
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SMD capacitors
X7E caps are not recommended.
Ralph Mowery a écrit : I started working with the SMD parts a year or so ago. I decided to stock up on some from ebay where you get strips of 10 each of about 50 valuse for a couple of bucks. In this assortment were some 2.2 and 10 uF capacitors. For the most part capacitors I am used to working with valuse round 1 uF and up are usually polarity sensitive. Are the the large values non polar like the smaler values ? I have not had time to look at them under my microscope to see if they look different. |
#8
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SMD capacitors
"Ralph Mowery" wrote in message k.net... In article , says... I'm not sure I understand your question. Whether a cap is polarized or not depends on the type cap. Tant's and Al are polarized (in general) and ceramics aren't. That may be the key. The listing did not say what kind of capacitors they are, just SMD and the value and voltage rating. Whatever they are, they are probably the same material, so the larger ones won't be ploarized either. I did notice the voltage on them is only 10 volts instead of 25 and 50 like the others. The lower voltage ratings are probably tantalum, polarity is *VERY* important. Don't be fooled by large capacitance values - I've seen a brochure for MLCC capacitors up to 180uF. SMD tantalum caps are usually encapsulated (after a fashion) and usually have markings. SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes I've encountered MELF round glass encapsulated MLCC caps on high end equipment. |
#9
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SMD capacitors
In article , gangprobing.alien1
@virginmedia.com says... The lower voltage ratings are probably tantalum, polarity is *VERY* important. Don't be fooled by large capacitance values - I've seen a brochure for MLCC capacitors up to 180uF. SMD tantalum caps are usually encapsulated (after a fashion) and usually have markings. SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes I've encountered MELF round glass encapsulated MLCC caps on high end equipment. Yes, the polarity is very important if the capacitor has one. I have not installed any of thse backwards to see what happens as of yet. I have seen the old aluminum and tantalum one blow over the years. I am not used to seeing capacitors ( other than large AC and speaker crossover) much over 1 uF. I can see why they don't mark most of the SMD, just no room but with micro printing there may be a way but it would cost. Even buying them from Digikey and Mouser they are very inexpensive compaired to the old point to point components. As mentioned, been working with components for over 50 years,but just started with the SMD in the last year. Could not justify the items it took to do that for just a hobby. Now they have came down a lot. Like the China hot air rework station for about $ 60 and a $ 200 microscope. The hot air station is probably no where near good enough for regular shop work,but good enough for hobby,and if it breaks, the replacement is not that much. I am learning a lot about the capacitors with the help here. |
#10
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SMD capacitors
On Tuesday, 29 August 2017 22:55:42 UTC+1, Ralph Mowery wrote:
In article , gangprobing.alien1 @virginmedia.com says... The lower voltage ratings are probably tantalum, polarity is *VERY* important. Don't be fooled by large capacitance values - I've seen a brochure for MLCC capacitors up to 180uF. SMD tantalum caps are usually encapsulated (after a fashion) and usually have markings. SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes I've encountered MELF round glass encapsulated MLCC caps on high end equipment. Yes, the polarity is very important if the capacitor has one. I have not installed any of thse backwards to see what happens as of yet. I have seen the old aluminum and tantalum one blow over the years. I am not used to seeing capacitors ( other than large AC and speaker crossover) much over 1 uF. I can see why they don't mark most of the SMD, just no room but with micro printing there may be a way but it would cost. Even buying them from Digikey and Mouser they are very inexpensive compaired to the old point to point components. As mentioned, been working with components for over 50 years,but just started with the SMD in the last year. Could not justify the items it took to do that for just a hobby. Now they have came down a lot. Like the China hot air rework station for about $ 60 and a $ 200 microscope. The hot air station is probably no where near good enough for regular shop work,but good enough for hobby,and if it breaks, the replacement is not that much. I am learning a lot about the capacitors with the help here. I've seen SMDs where one end is a bit pointed to indicate polarity. If there's really nothing to indicate polarity it's most likely nonpolar. Hook one up & see, not that hard. NT |
#11
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SMD capacitors
Ralph Mowery wrote on 8/29/2017 5:55 PM:
In article , gangprobing.alien1 @virginmedia.com says... The lower voltage ratings are probably tantalum, polarity is *VERY* important. Don't be fooled by large capacitance values - I've seen a brochure for MLCC capacitors up to 180uF. SMD tantalum caps are usually encapsulated (after a fashion) and usually have markings. SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes I've encountered MELF round glass encapsulated MLCC caps on high end equipment. Yes, the polarity is very important if the capacitor has one. I have not installed any of thse backwards to see what happens as of yet. I have seen the old aluminum and tantalum one blow over the years. I think you just answered your question. If the caps have polarity markings they are polarized. If they don't have polarity markings, how do you know you have any installed correctly? I am not used to seeing capacitors ( other than large AC and speaker crossover) much over 1 uF. MLCCs (which are ceramic) can be found above 1 uF. I often use them at 10 uF and I know they are available at higher values. The product of capacitance and voltage determines the size, so in a given size the voltage will drop as the capacitance approaches the max value. There are also different material ceramic caps with widely different tolerances and voltage/temperature responses. X5R is a good general purpose type of ceramic cap. I can see why they don't mark most of the SMD, just no room but with micro printing there may be a way but it would cost. Even buying them from Digikey and Mouser they are very inexpensive compaired to the old point to point components. As mentioned, been working with components for over 50 years,but just started with the SMD in the last year. Could not justify the items it took to do that for just a hobby. Now they have came down a lot. Like the China hot air rework station for about $ 60 and a $ 200 microscope. The hot air station is probably no where near good enough for regular shop work,but good enough for hobby,and if it breaks, the replacement is not that much. I am learning a lot about the capacitors with the help here. While the idea of a cap is pretty simple, the realities can get pretty complex. -- Rick C Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998 |
#12
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SMD capacitors
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#13
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SMD capacitors
Ralph Mowery wrote on 8/31/2017 10:27 AM:
In article , says... I think you just answered your question. If the caps have polarity markings they are polarized. If they don't have polarity markings, how do you know you have any installed correctly? Someone sent a pix with several kinds of the SMD capacitors. A couple of them had a pointed tit on one end. I did not know that,so would have missed that as a polariaty mark. If I had just looked at the capacitor, I probably would have dismissed it as just a blob of material instead of a polarity mark. I don't know if that *is* a polarity mark. I'm not sure what you are describing, but I don't recall seeing any SMD polarized capacitors that don't have *clear* markings of polarity. Do you have an image or can you find a similar cap on the Internet? Sometimes it helps to know all the small details of the components. I don't know, but guess that some could not have any marking and it could depend on how they are placed in the reel they come in. I've never seen polarized caps that weren't marked. I've never seen polarized caps that relied solely on the reel orientation to indicate polarity. -- Rick C Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998 |
#14
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SMD capacitors
In article , says...
I've never seen polarized caps that weren't marked. I've never seen polarized caps that relied solely on the reel orientation to indicate polarity. Here is a link to a px of some SMD capacitors. The two on the right have that little tit I mentioned. It could be mistaken by someone like me that has never seen one as just some excess solder when it was made. https://drive.google.com/drive/folde...l9MRk1sdnA3ajA There probably are not any that are not marked in some way. I was just guessing at the reel thing. As mentioned it is a hobby now and upto a short while ago I had not messed with any of the SMD. There have been lots of advances and changes in the components over the years. Just more to learn. I still have trouble with the values of some components being packaged in a small package. Just hope I am not sounding like some of the other older people on here with the SMDs. |
#15
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SMD capacitors
Ralph Mowery wrote on 8/31/2017 1:11 PM:
In article , says... I've never seen polarized caps that weren't marked. I've never seen polarized caps that relied solely on the reel orientation to indicate polarity. Here is a link to a px of some SMD capacitors. The two on the right have that little tit I mentioned. It could be mistaken by someone like me that has never seen one as just some excess solder when it was made. https://drive.google.com/drive/folde...l9MRk1sdnA3ajA Ok, these are un-encapsulated tantalum caps and that pin is a part of the device internal connections. They are the same part as the yellow ones to the left (and maybe the black ones too, but not the round ones which are electrolytic), but without the plastic coating to make them smaller. Yes, the point might look like excess solder, but if you use a part without looking at the data sheet you are screwing up. There probably are not any that are not marked in some way. I was just guessing at the reel thing. As mentioned it is a hobby now and upto a short while ago I had not messed with any of the SMD. There have been lots of advances and changes in the components over the years. Just more to learn. I still have trouble with the values of some components being packaged in a small package. Trouble? You mean you have trouble accepting the small sizes? Just hope I am not sounding like some of the other older people on here with the SMDs. Only a little... Wanting to learn new stuff is what is setting you apart. It is hard to go with new ideas when you've been doing the same thing for a long time, especially when the eyesight makes it hard. But it's not impossible. I have essential tremor but I still make stuff from time to time. When it's work I let an assembly house deal with it. -- Rick C Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998 |
#17
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SMD capacitors
On Monday, August 28, 2017 9:44PM , Ralph Mowery wrote:
In article , says... If they are MLCC, the capacity can be quite high maybe even 10uF these days, but very low V and a susceptibility to metal migration it PbF soldering temp requirement fracture the ceramic at laying I have read about the need to slowly heat the capacitors to keep them from fracturing. I don't mean to go further on a tangent and I have no experience with the A+++ related computer hardware construction and repair, but I know fans keep computer hardware cool. But with cold capacitor heat rising to fast, should something like incandescent light bulb first turn-on before cooling fans kick-in in a CPU tower-area to keep hardware temperature more at an exact setting? |
#18
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SMD capacitors
On Saturday, 25 November 2017 19:43:37 UTC, wrote:
On Monday, August 28, 2017 9:44PM , Ralph Mowery wrote: In article , says... If they are MLCC, the capacity can be quite high maybe even 10uF these days, but very low V and a susceptibility to metal migration it PbF soldering temp requirement fracture the ceramic at laying I have read about the need to slowly heat the capacitors to keep them from fracturing. I don't mean to go further on a tangent and I have no experience with the A+++ related computer hardware construction and repair, but I know fans keep computer hardware cool. But with cold capacitor heat rising to fast, should something like incandescent light bulb first turn-on before cooling fans kick-in in a CPU tower-area to keep hardware temperature more at an exact setting? can you put that in english? |
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