-
WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!
Capacitor question
- Thread starter Doobrey
- Start date
Yes, they can be adjacent and touching. Just make sure the lead legs do not touch and all will be fine.
sam_adams
Addicted to Fun and Learning
- Joined
- Dec 24, 2019
- Messages
- 851
- Likes
- 1,972
Any replacement for radial-leaded caps should have the same lead spacing as the original. If you replace them with caps with a different lead spacing you will have to bend the leads too close to the entry point on the cap which will stress the leads at that point and could result in a seal leak or premature lead failure. A proper replacement will drop right into the holes in the PCB—without having to form the leads—and the cap body will be tight against the PCB. Be smart. Study the spec sheets for the replacements and choose caps with the correct lead spacing.
As far as cap brands go, suppliers like Mouser and Digikey carry most of the well known brands. All around good choices are Panasonic FM series for power supply and general purpose use and Nichicon Fine Gold Muse for signal path. Both of those brands are priced reasonably and you will not gain much from paying for higher priced brands.
One other thing, most new designs use lead free solder. Don't be tempted to use 63/37 leaded solder on boards that have lead free on them. Buy the right lead free solder and get tips for your soldering iron to use specifically with lead free solder.
As far as cap brands go, suppliers like Mouser and Digikey carry most of the well known brands. All around good choices are Panasonic FM series for power supply and general purpose use and Nichicon Fine Gold Muse for signal path. Both of those brands are priced reasonably and you will not gain much from paying for higher priced brands.
One other thing, most new designs use lead free solder. Don't be tempted to use 63/37 leaded solder on boards that have lead free on them. Buy the right lead free solder and get tips for your soldering iron to use specifically with lead free solder.
NormB
Member
- Joined
- Feb 21, 2020
- Messages
- 56
- Likes
- 39
Schematic from a 35 year old Technics ST-9038 FM tuner. I put in an OPA2134PA opamp, some decoupling caps on the +/- power pins to ground, replaced the caps C409/C410 with NP Muse 4.7/25V values. thought it pretty weird they weren't polarized. tuner sounds GREAT otherwise. Now I'm "worried" about the other 97 caps in the unit.
No, actually I use it daily, music, voice, Hot Jazz Saturday night from American University in DC all sound better than before.
No, actually I use it daily, music, voice, Hot Jazz Saturday night from American University in DC all sound better than before.
Yes, I've used those, too. A good choice when film caps won't fit an existing design.
You do whatever you want. As you put it, 'peace of mind' after dismantling the device, doing the the soldering job on that industrial board with your personal equipment? I would rather follow the saying "If not broke, don't fix." Admittedly it'll take a while now to find peace again after revealing those, as was said, bottom of the barrel capacitors. A good measurement of the device's performance might help with that. You would need that anyway as to after prove your workings to be correct. (Peace of mind.)
Last edited:
- Thread Starter
- #28
I didn’t think I would need to make a measurement of the amplifier after capacitor change? after all they are identical value replacements just better quality.
Yup. Replaced all the cheap polar coupling caps in my DCX2496 with those. It may not have helped, but it made me feel better!
I was under the impression, that this board leans more towards the objectivist perspective. So I wars tempted to share some personal experience. To start with replacing parts because of hear-say claims about the "musical quality" of certain top tier caps, opamps etc didn't do it for me. I ruined some devices permanently, before I got aware of my personal problem. I had to switch focus from the stereo's imaginated quality (or not) to just trust the latter and listen to what the program had to tell. My ability to measure performance quite reliably helped me out of that actually realy vicious circle. A discussion with my doctor got me clear on the general limitations and vulnerability of the human hearing. Not the least I came to deeply distrust not the devices but the advertizing** and misinformed talking in the internet.
I don't know what your proficiency is with soldering a (multilayer?) circuit board. I personally wouldn't be happy (piece of mind) to have some crampy contacts in 'my signal chain'. Guess from what I know that--and I have both experience and semi-pro tools.
No offense, just my 2cc
** example given, not all recordings are optimzed for headphone listening, so that might be a contributing cause for a creeping discomfort with the overall experience
Last edited:
May I ask why? I always use 60/40 solder for my repairs as it flows better. Anything I build also is soldered with 60/40.
I can understand why lead-free has been mandated for consumer and industrial equipment due to electronic waste, but I find it interesting that leaded solder is still permitted (if not mandatory) for military and medical equipment.
S.
All what described ist the right way. On the other hand I had original manufactured PC boards where the caps radial leads were already bended prior to insertion. Myself when I replace a radial cap try to use the right spacing. If not available the leads can be bended carefully without problem what is my expericence. Further, of course all soldering in the EU must be lead free by law except military stuff. I work still with the old leaded solder which makes the least problems. And I use it on lead free pc boards when replacing a component. Never had a problem with this.
I am also interested on this. Can you please elaborate? Is there a technical reason not to use lead containing solder on an otherwise lead free board? I understand the other way around but I would like to know if I am missing something.
Thanks.
Not being familiar with metal properties. But before lead free came almost all soldering with various metals from copper, silver, gold, brass to some others was the standard. So this was where I grew up with. There may be exotic layers on a pc board which are not compatible to lead but I can't think of any. Lead free solder has a higher melting temperature which is worse to some material. But it thus may withstand higher temperatures. For audio gear I don't think that this is an issue.
- Thread Starter
- #35
Even if the the measurements slightly change a bit I don’t mind. Like I said caps are identical replacements so I’m not worried about affecting anything when my aim is to actually increase its life time with quality parts. I’m not sprinkling over audiophile magic dust I’m doing it for peace of mind. Any day I’d take Panasonic or nichicon over jamicon, Teapo and novel caps.
If not broke don't fix ... Lifetime of caps is related to temperature, voltage and maybe current. Give the particular use case here I would expect a million of years out of your equipment. That said, I also understand your urge to plan for the future.
sam_adams
Addicted to Fun and Learning
- Joined
- Dec 24, 2019
- Messages
- 851
- Likes
- 1,972
The best choice for soldering with lead-based solders is 63/37. Why? A 63/37 ratio (63% Lead, 37% Tin) is a eutectic type solder. It melts at a lower temperature and is liquid at only its melting point (183˚ C) going directly to solid with no semi-solid state. This ratio provides better wetting and flow with less drossing (material that appears on the surface of the solder joint as it cools giving it a dull appearance) and less chance for bridging between closely spaced solder points. It means that you will have better joints with fewer defects and better reliability.
Most automated assembly has used or uses SAC305 lead-free solder (Other alloys might also be used like Sn100c or Sn99c.). This works well in production, but not so much in rework situations. Higher melting temps means that it is more likely that you're going to damage the board during rework if you don't have superior skills and equipment.
Why shouldn't you mix the different types? Solder is an alloy with carefully selected ratios of elemental metals to produce a mixture with certain desired properties. When you mix a different alloyed metal with the original—leaded solder with lead-free solder–you get an alloy with completely different properties. Even if you clean the lead-free solder from the solder pad for a component, the pad will still have a coating of the lead-free solder on it that will alloy with whatever type of solder you are using for rework. You now have an alloy layer between the original lead-free solder and your rework solder with unknown properties. The possible failure modes would be numerous.
From a tool standpoint and why you should use different tips for your soldering iron for leaded and lead-free work? First is the contamination issue with different alloys that you want to avoid. Use different tips or completely different irons to avoid that. If you had spent thousands on a rework station for lead-free rework you would definitely not want to have your work compromised like that.
Second, higher temps for lead-free solder increase the oxidation rate of the tip. The tip temperature should only be high enough to adequately heat the parts and melt the solder without burning the board or overheating the part. You have to be meticulous in keeping the tips cleaned and wetted to ensure long life. Additionally, unless you specifically choose a Ag-free alloy (silver-free), lead-free solders with silver in them are hard on the iron tips causing them to wear out quickly.
Most automated assembly has used or uses SAC305 lead-free solder (Other alloys might also be used like Sn100c or Sn99c.). This works well in production, but not so much in rework situations. Higher melting temps means that it is more likely that you're going to damage the board during rework if you don't have superior skills and equipment.
Why shouldn't you mix the different types? Solder is an alloy with carefully selected ratios of elemental metals to produce a mixture with certain desired properties. When you mix a different alloyed metal with the original—leaded solder with lead-free solder–you get an alloy with completely different properties. Even if you clean the lead-free solder from the solder pad for a component, the pad will still have a coating of the lead-free solder on it that will alloy with whatever type of solder you are using for rework. You now have an alloy layer between the original lead-free solder and your rework solder with unknown properties. The possible failure modes would be numerous.
From a tool standpoint and why you should use different tips for your soldering iron for leaded and lead-free work? First is the contamination issue with different alloys that you want to avoid. Use different tips or completely different irons to avoid that. If you had spent thousands on a rework station for lead-free rework you would definitely not want to have your work compromised like that.
Second, higher temps for lead-free solder increase the oxidation rate of the tip. The tip temperature should only be high enough to adequately heat the parts and melt the solder without burning the board or overheating the part. You have to be meticulous in keeping the tips cleaned and wetted to ensure long life. Additionally, unless you specifically choose a Ag-free alloy (silver-free), lead-free solders with silver in them are hard on the iron tips causing them to wear out quickly.
Similar threads
