Replace SMD capacitors with through hole  - Page 1
Forum section: electronics / beginners

author: Maurizio1957
author_rank: Contributor
timestamp: January 28, 2023, 09:18:49 am
content: Hello everyone.I am trying to repair an Advantest R3463 spectrum analyzer (seehttps://www.eevblog.com/forum/repair/advantest-r3463-trouble/msg4463401/).I would like to replace the SMD electrolytic capacitors on the various boards, but many of them are in very hard to reach spots on the boards. Would replacing with through hole capacitors be easier, what do you think? ( see the last picture)[ Specified attachment is not available ]Thanks to all, Maurizio

author: Watth
author_rank: Frequent Contributor
timestamp: January 28, 2023, 01:18:29 pm
content: I'm not a pro solderer, but my impression is that if you can de-solder these SMD capacitors, you'll be able to replace them with identical SMD parts.If you use hot air, I'd suggest to tape the small SMD components with polyamide (kapton) tape to keep them in place.How are you used to soldering?

author: coromonadalix
author_rank: Super Contributor
timestamp: January 28, 2023, 02:26:00 pm
content: i would say you will create a mess, and you could rip some pcb pads etc ...

author: mariush
author_rank: Super Contributor
timestamp: January 28, 2023, 02:58:08 pm
content: I'm in the "yes, replace with leaded capacitors" camp, leaded capacitors are more reliable.Watch from around 10:00 the video below, to see how he removes surface mount capacitors and solders leaded capacitors.Gentle pressure on the capacitor to keep the rubber bottom pressed onto the pcb, small left-right twists to weaken the thin leads until the break.

author: Infraviolet
author_rank: Super Contributor
timestamp: January 28, 2023, 09:30:22 pm
content: I don't see how you can replace SMD caps with through-hole, there aren't any through holes on the boards which the replacement caps can go in to. What you could perhaps do though is replace those SMD electrolytic with SMD ceramic*. IF they aren't at the very high end (one can get 100uF ceramics 6volt in 1210 SMD format, one can't get much higher) then ceramics, while pricier at scale for a manufacturer, could be available at the same capacitance and voltage rating, and have packages which could be easier to solder to those pads as they are soldered at the ends not the undersides, I suspect a larger sized SMD run at the right angle could cross between the existing pads ok at an angle.I've never seen electrolytic SMD caps in 0603/0805/1210/any typical box like format, but if you can find them where you solder at the ends then these would be perfect replacements for those vertical can SMD electrolytics.*Make sure the circuit isn't one which relies on the higher ESR of electrolytic caps to suppress what could otherwise be LC voltage spikes when powering on.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: January 28, 2023, 10:06:36 pm
content: As long as space is available that is what I have done for many yearswith no problems.Jeff

author: Rabbitoose
author_rank: Contributor
timestamp: January 28, 2023, 10:28:17 pm
content: The technique of removing the capacitors by bytwisting them in this video is very inspiring to me. Thanks!

author: Maurizio1957
author_rank: Contributor
timestamp: January 29, 2023, 09:44:36 am
content: Thanks everyone for the replies.The technique I used is exactly the one you see in the video; rotatethe capacitors right and left until the pins break, reassemble the smd where there is room to weldthem, otherwise put through-hole capacitors with the pins bent.Checking the capacitors that I remove I see a high esr, particularly for the low value ones (6.8 uF), I hope it isthe cause of the problems with this instrument...Greetings, Maurizio

author: Siwastaja
author_rank: Super Contributor
timestamp: January 29, 2023, 09:50:20 am
content: Quote from: Maurizio1957 on January 28, 2023, 09:18:49 amWhy?!This implies you think you know better than the original designers.Don't make random component substitutions without good reasons.

author: Manul
author_rank: Super Contributor
timestamp: January 29, 2023, 01:02:12 pm
content: Quote from: Maurizio1957 on January 29, 2023, 09:44:36 amIf you read almost any capacitor datasheet where they list data of various working voltage and capacitance combinations of particular capacitor series, you will notice, that small value capacitors have high ESR. This is normal. To determine if it is too high you need to compare it with the datasheet and use same testing conditions (for example, 100kHz at room temperature).Generally speaking, if capacitors in the device are of quality brand and they work below 50 - 60 degrees celcius, I never even check them until I have a strong evidence (for example high measured ripple voltage). At lower temperatures good quality capacitors usually last very very long, like decades.

author: Watth
author_rank: Frequent Contributor
timestamp: January 29, 2023, 01:07:16 pm
content: Quote from: Siwastaja on January 29, 2023, 09:50:20 amThe manufacturer chose this components for budget and practicality (i.e. for a pick&place machine).Replacing these can be the occasion to update these capacitors with higher quality ones. And as the new ones are mounted manually, THT or SMD is up to OP.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 29, 2023, 01:34:40 pm
content: Quote from: Watth on January 29, 2023, 01:07:16 pmSo youreallythink spectrum analyzer, a lab instrument, was designed with crap quality budget parts,andthat you are able to choose not only better quality parts from better supply chains, but also able to understand every parameter that goes into choosing each capacitor, being able to reverse-engineer the circuit around it, and so on? And not only you are capable of doing this, you have already done this, for each capacitor in said logic analyzer, and the result was these are wrong capacitors and need replacement?I call not only bullshit, but Dunning-Kruger as well.Look, some of us actually design electronics so we know what goes into choosing the parts.Do not destroy electronics with random component substitutions. Sometimes capacitors do go bad, but don't randomly replace every capacitor. Instead, look for advice online about which capacitors are known to go bad, and if/when it is not a known failure mode (pretty often), don't do anything.But in the end, if your hobby is to ruin electronics and get kicks out of it, be my guest.And there is no fundamental difference between SMD/THT regarding parameters or reliability (except maybe tolerance against mechanical stress in high-vibration environment, usually not seen by lab instruments). If the SMD parts somehow were of poor quality or otherwise bad, I would replace them with SMD parts, plenty of offerings.

author: mariush
author_rank: Super Contributor
timestamp: January 29, 2023, 02:49:54 pm
content: Quote from: Maurizio1957 on January 29, 2023, 09:44:36 amCapacitors under 10-22uF CAN have relatively high ESR, let's say 1-2 ohm ESR.Ideally, you would determine the manufacturer and series and compare the values with what's in datasheet.For example see a pretty much standard nothing special from Nichicon (who made the 100uF 25v capacitors in your first picture) :https://www.nichicon.co.jp/english/products/pdfs/e-uwg.pdfThe 100uF 25v has 0.3 ohm ESR and 450mA current ripple.

author: jmelson
author_rank: Super Contributor
timestamp: January 29, 2023, 04:46:02 pm
content: I use similar caps in boards I produce. Sometimes they get damaged in shipping and need to be replaced. Unsoldering them is VERY difficult. What I might suggest is to cut the top of the caps apart with diagonal cutters until you get down to the rubber plug. then, pull the plug off the leads and remove the plastic foot. The whole idea of doing this is to not apply force to the PC board pads while hot as they can be ripped off the board. Depending on the quality of the board, the "hot peel strength" of the copper may be very weak.Then, removing the remaining leads should be easy without risk to the board, and you can solder radial lead caps to the board pads.Jon

author: Siwastaja
author_rank: Super Contributor
timestamp: January 29, 2023, 04:56:47 pm
content: Quote from: jmelson on January 29, 2023, 04:46:02 pmUsing just hot air, or trying to get the iron tip to melt all the tin by touching just the tiny exposed part is indeed difficult.However, preheating the whole board (using a hotplate / preheater) to temperature close to the melting point of solder helps tremendously.And you can keep the board at temperatures around 150degC or so for extended times without damaging anything. Makes soldering easypeasy, except you can't touch the board with bare hands.

author: Watth
author_rank: Frequent Contributor
timestamp: January 30, 2023, 11:16:22 am
content: Quote from: Siwastaja on January 29, 2023, 01:34:40 pmSo you had the possibility to support your point with arguments.You instead chose to be a condescending butthole with its lot of arguments by authority and a "do you know who I am?" attitude. All that in thebeginners' part of the forum.Bra-vo! I am very impressed.By the way, would you call this answer Dunning-Krüger bovine feces too?Quote from: mariush on January 29, 2023, 02:49:54 pm

author: Watth
author_rank: Frequent Contributor
timestamp: January 30, 2023, 11:19:17 am
content: Quote from: jmelson on January 29, 2023, 04:46:02 pmWhat do you think of the method in the vid posted by mariush :?

author: Siwastaja
author_rank: Super Contributor
timestamp: January 30, 2023, 11:21:31 am
content: Quote from: Watth on January 30, 2023, 11:16:22 amThe fact you skip all the arguments, and then claim there were no arguments, is discouraging.The #1 problem in Beginner's section is giving wrong advice. This is because beginners often truly don't know, and do not have means to evaluate if the information is correct or not. Therefore, I expect regulars to follow the simple "if you have no idea about it, do not post" pattern. That way, we don't have to waste other's time in bickering. Instead, you are amplifying the "random capacitor replacement" cult, and start a fight when corrected.If you can't stand being corrected in a direct and honest way, you can choose to ignore. In the mean time, consider stopping the ruining of this Beginner's forum by (1) wrong information, (2) picking a fight with others who correct you in a way you don't like. In other words: grow up. This forum is not for your ego trip.QuoteI see no obvious error of any kind in the post by mariush. I could add that ESR for a 6.8uF part can be even more than 2 ohms. Even if OP reads something like 10 ohms, that would not necessarily indicate any problem.

author: Watth
author_rank: Frequent Contributor
timestamp: January 30, 2023, 11:41:04 am
content: Quote from: Siwastaja on January 30, 2023, 11:21:31 amYou read a lot more than I wrote. I only questioned the fact that anything but the exact same model would work." You are amplifying the "random capacitor replacement cult"." is a unsupported strawman. I don't see how you come to that conclusion.mariush somehow made the same point:Quote from: mariush on January 29, 2023, 02:49:54 pmI admit I should express my point as one of a non specialist, with cautions as to my little knowledge. But my point is the same as others': that if all relevant values are equivalent, the circuit should work the same.So in a beginners' forum, you need more knowledge sharing skills, and less "my ball are bigger than yours" testosterone-filled stance.

author: jmelson
author_rank: Super Contributor
timestamp: January 30, 2023, 05:26:52 pm
content: Quote from: Watth on January 30, 2023, 11:19:17 amWell, it worked GREAT on the specific brand/style on that board, but I can't be sure it would work so well on other types. Since the project was to replace old, worn out caps, there's no harm in totally destroying the capacitors from the top down and not putting stress on the pads.But, you could try that method more carefully than in the video and watch for signs the pad is starting to lift. Maybe the caps on my boards are more robust than the video ones, sometimes the cap is knocked off my boards and the pad comes off with it.Jon

author: Maurizio1957
author_rank: Contributor
timestamp: January 31, 2023, 03:55:14 pm
content: About ESR and old capacitors:I added a 15 ohm resistor in series to a new 6.8 uF SMD capacitor to get the same reading from my homemade ESR meter as I have from a 6.8 uF capacitor disassembled from the spectrum analyzer, usual thing with the other higher rated capacitors, although not as bad.As I said in my first post, I am trying to repair an Advantest R3463 that i got as a gift from a friend, telling me " the repair is too expensive, use it to recover parts...", so I'm trying...Greetings, Maurizio

author: chick0n
author_rank: Regular Contributor
timestamp: February 06, 2023, 07:06:24 pm
content: I replaced some smd caps in my R3273 with through hole caps / bent the pins. All SMD caps where leaking, but still working. And it didnt made much difference. So the caps advantest used seem to be very high quality. They still work after they leak, and the leakage doesnt destroy the PCB. Also the leakage dried. Looks a little bit like rosin...I also only replaced the caps responsible for DC-Smoothing (99%).It really isnt always necessary, to replace every cap...

author: PostumiDellaSbornia
author_rank: Newbie
timestamp: May 13, 2024, 04:06:43 pm
content: As a fellow Finn, I comletely disawov this post - both the content and the attitude. I think using leaded capacitors instead of SMD ones for manual repairs is perfectly viable as long as the leads are kept sufficiently short and the parameters are adequate.Quote from: Siwastaja on January 29, 2023, 01:34:40 pm

author: Siwastaja
author_rank: Super Contributor
timestamp: May 13, 2024, 04:27:24 pm
content: Quote from: PostumiDellaSbornia on May 13, 2024, 04:06:43 pmWelcome to the forum! Here we usually do not bump old threads unless we have something significant new information or viewpoint to add. This is because the forum software only warns about the topic being old once - only you saw the warning, to others, this looks like a recent thread unless they carefully look at dates. When warned about something, be responsible and do not just ignore the warning: think why you are being warned, use your brain. Same thing as with compiler warnings in programming.I agree leaded capacitors can be viable alternatives,ifa part needs replacement,anda leaded part fits. Nobody ever said otherwise, so. Note that the context is replacing all capacitors with different types because the OP "wants to", not because the capacitors need replacement.Just bumping a random old thread without having anything to say, just to pick a fight with regulars, is a pretty bad start. Especially on a beginner's section, where we should be easy on beginners, avoiding unnecessary confrontation (but wrong information, too).

author: Maurizio1957
author_rank: Contributor
timestamp: May 13, 2024, 04:46:16 pm
content: I'm surprised to see this discussion reopened! This Advantest didn't load the operating system, it was blocked at startup, and I made the bet "I'll try to change the electrolytics..."I replaced about 100 capacitors on this spectrum analyzer, most of them SMD, some through-hole where there wasn't room to solder the SMD, and now the instrument works...Cheers, Maurizio