Replace bad caps with Panasonic caps

[liukuohao]

Re: Replace bad caps with Panasonic caps

My thoughts...

1. Removing the plastic cover saves money.

2. Polymer capacitors don't need vents so there's a flat top where it's convenient to print stuff and make clear notation of the negative side. Electrolytic capacitors needed to have the top clear of everything, for safety. Regular paint probably had little adherence on the sides and since it's curved, the printing process was probably difficult, hence the need for plastic wrap.

3. Printing on top is beneficial, it makes it easy for machines that automatically check how parts are placed to detect the negative strip and to optionally read the characters (making sure the machine or person inserted the proper capacitor in the proper position)

4. A majority of the manufacturing process can be reused to create surface mount capacitors, which are like regular capacitors but with a rubber square on the bottom instead of leads.

5. With some polymer capacitors, the height is too small to fit everything needed (capacitance, voltage, series, temperature, polarity).

Some polymer capacitors have diameters so small that you just can't fit all information on top in a long way.

For example, you probably can't fit 1000uF and 2.5v on a capacitor that's only 8mm in diameter, so you write 102 instead of 1000 ( 10 x 10^2 = 10x 100 = 1000uF) and they use the code "0E" to represent 2.5v. See datasheet and the chart for such a series of capacitors:

Hi mariushm, thank you for explaining the reason!

[liukuohao]

Re: Replace bad caps with Panasonic caps

If the Sanyo capacitors are not leaking, but......
I have been having the Pentium 3 motherboard for more than 10 years.

1) Can assume the Sanyo capacitors have gone way pass its working life span
and it is about time to replace it?

2) I discovered that 3 Sanyo capacitors located next to the ATX socket are not
firmly sitting on the motherboard, and can be pushed away on angle something like
this: \ or /. The slash depicts the position of the capacitors can be moved.
Does this mean the capacitors is actually bulging from the bottom of the capacitors?

[momaka]

Re: Replace bad caps with Panasonic caps

If the Sanyo capacitors are not leaking, but......
I have been having the Pentium 3 motherboard for more than 10 years.

1) Can assume the Sanyo capacitors have gone way pass its working life span
and it is about time to replace it?

Usually no. Good Japanese brands will easily last more than 10 years, especially if they are not abused (i.e. heat, overvoltage, etc.... which on your Pentium 3 motherboard, I'm sure they were not). Heck, I have an old socket 7 Pentium motherboard with original Sanyo and I.Q. (I.Q. is a crap brand) caps, and it still works great. Even my Pentium II motherboards all work fine, and some have extremely crappy caps. They just weren't stressed and that's why they lasted.

2) I discovered that 3 Sanyo capacitors located next to the ATX socket are not firmly sitting on the motherboard, and can be pushed away on angle something like this: \ or /. The slash depicts the position of the capacitors can be moved.
Does this mean the capacitors is actually bulging from the bottom of the capacitors?

Not necessarily (and I would say no).
Sometimes, the capacitors can be mounted a bit high on the board (usually a factory thing). This will allow them to lean sideways like you noticed.
Also, Sanyo capacitors have a rubber bung on the bottom that is raised and has a channel in it - this is to allow any liquids to dry from under the capacitors after the boards have been washed after the soldering process.

[liukuohao]

Re: Replace bad caps with Panasonic caps

Usually no. Good Japanese brands will easily last more than 10 years, especially if they are not abused (i.e. heat, overvoltage, etc.... which on your Pentium 3 motherboard, I'm sure they were not). Heck, I have an old socket 7 Pentium motherboard with original Sanyo and I.Q. (I.Q. is a crap brand) caps, and it still works great. Even my Pentium II motherboards all work fine, and some have extremely crappy caps. They just weren't stressed and that's why they lasted.


Not necessarily (and I would say no).
Sometimes, the capacitors can be mounted a bit high on the board (usually a factory thing). This will allow them to lean sideways like you noticed.
Also, Sanyo capacitors have a rubber bung on the bottom that is raised and has a channel in it - this is to allow any liquids to dry from under the capacitors after the boards have been washed after the soldering process.

Hmmm....if the your theory is right, then it has to be the Power Supply Unit.
Because I have a strange problem with my ASUS P3V4X motherboard, sometimes,
it just cannot detect ALL memory slots when RAM are inserted.

I took my old PSU out and open up and found a whole bunch of CAPXON noise/ripple
filter caps near output rails = +5v, +3.3v, +12v, -12v, -5v, +5vsb.

None of the CAPXON caps are bulging nor leaking, they all look normal
to me.

So the question is do I waste the time and money to replace the
CAPXON caps or dump it and buy a new one instead, since you
already CAPXON caps are shitty caps and unreliable.

Side questions.....

What does a Pentium 3 motherboard need a PSU with -5v for it to boot up.
I try to boot up with modern PSU (without the -5v rail), it won't fire up at all?

Should I buy a ESR meter to test the SANYO caps to see whether they have
been under stress?

[momaka]

Re: Replace bad caps with Panasonic caps

Hmmm....if the your theory is right, then it has to be the Power Supply Unit.
Because I have a strange problem with my ASUS P3V4X motherboard, sometimes,
it just cannot detect ALL memory slots when RAM are inserted.

Don't jump to conclusions just yet .

Yes, it could be the power supply, or it could also be just the motherboard itself and not related to the caps at all. I say that because you have an ASUS motherboard, and they can be "picky" or buggy sometimes. But let's assume that is not the case for now and try our other options.

Concerning the RAM: Have you tested each memory module individually? Are they all rated for the same speed? Did you ever try running those RAM sticks together before? Did they work fine and the problem just appeared now?
Try using one module at a time. If it works, try adding another. Keep doing so until the motherboard cannot boot.

Lastly, check your motherboard's manual for any settings and compatibility issues, especially about the RAM.

I took my old PSU out and open up and found a whole bunch of CAPXON noise/ripple filter caps near output rails = +5v, +3.3v, +12v, -12v, -5v, +5vsb.

None of the CAPXON caps are bulging nor leaking, they all look normal
to me.

So the question is do I waste the time and money to replace the
CAPXON caps or dump it and buy a new one instead, since you
already CAPXON caps are shitty caps and unreliable.

That depends on the power supply you have. It is best to post some pictures of its insides here so we can suggest if it's worth your time or not. Some PSUs are so crappy and "gutless" that it's not worth repairing them at all. However, if you do have a decent PSU, then some new high quality caps will keep it working for a very very long time.

Also, it depends what kind of power supplies are available on your market and at what price. A new crappy PSU with crappy caps will not solve anything. On the other hand, if you can find a decent power supply for a decent price, then buy a new one.

What does a Pentium 3 motherboard need a PSU with -5v for it to boot up.
I try to boot up with modern PSU (without the -5v rail), it won't fire up at all?

Probably because your motherboard has an ISA slot. IIRC, the board might require a -5V rail to be present even if there is nothing in the ISA slot.

Should I buy a ESR meter to test the SANYO caps to see whether they have been under stress?

If you plan on doing more repairs and can find an ESR meter for a good price, then, yes, buy one. Otherwise, it may not be worth the cost.

[liukuohao]

Re: Replace bad caps with Panasonic caps

Ok, momaka,

I have followed your advice......
I have taken a couple pictures of the internal view of my Enligth PSU.
Please see below.

If those crappy CAPXON caps need to be replaced, do I need to replace
all of them, as a couple of them hid underneath the huge heat sink which
quite impossible to replace, unless I know how to remove the obstruction.

Another option is to buy a new PSU but the problem is none of the modern
PSU has a -5v rail. I tried a couple of them which has got no -5v rail, and
the motherboard does not boot up. The only way to boot up is to have an
old PSU that has -5v rail.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

BTW, the 4 pieces of RAM was slotted into position and the BIOS
did detect ALL 4 pieces correctly and showed on the screen, that was 1GB RAM.

So it has been working fine for quite some months, note that the motherboard
was working as a firewall at 24/7 under a very warm conditions.

The weird problem only arise when the PC was not turned off for a number
of months unused(resting for a long holiday). Then only last month,
I booted up the PC and this memory detection issue came into in existence.

I have to swap out and in the RAM modules(place in a different position
compare to last time) only then the BIOS will fully recognize ALL memory
slots, otherwise, it will sometimes show 512MB during booting up the system.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Appreciated your continuous advice.THANK YOU!!

[liukuohao]

Re: Replace bad caps with Panasonic caps

Hi

Is there anyone can tell me whether I need to change the CAPXON capacitors
in the PSU? Since they are considered a bad capacitors in the forum?

Thank you.

[mockingbird]

Re: Replace bad caps with Panasonic caps

Yes. The datecode on them reads "346", which is the 46th week of 2003. These capacitors are more than 10 years old, and they're a lousy brand, so it's very likely they're no good.

[liukuohao]

Re: Replace bad caps with Panasonic caps

Yes. The datecode on them reads "346", which is the 46th week of 2003. These capacitors are more than 10 years old, and they're a lousy brand, so it's very likely they're no good.

Thank you for your reply.

So, I need to replace those capacitors as seen in image no.1. = Image_2106.jpg
That is those noise filter caps.

How about the massive caps like the black ones, leave them alone?

Also how about the one that in the middle (referring to image no.3)
which is sitting alone underneath the heat sink?

[mockingbird]

Re: Replace bad caps with Panasonic caps

You can leave the two large ones. You should replace everything else.

If you need help finding good replacements, I suggest you make a post with a list of the caps in the following format:

1) Voltage, Capacity, Diameter * Height, Brand, Series
2) etc...

It might be preferable to just purchase a new PSU, because it might end up costing the same.

[momaka]

Re: Replace bad caps with Panasonic caps

I have taken a couple pictures of the internal view of my Enligth PSU.
Please see below.

Thank you.
Your power supply seems very well-built. Definitely worth saving and recapping.

If those crappy CAPXON caps need to be replaced, do I need to replace all of them, as a couple of them hid underneath the huge heat sink which quite impossible to replace, unless I know how to remove the obstruction.

Usually, it is fine to replace just the output caps - that is, the caps associated with the 3.3V, 5V, 12V, -5V, -12V, and 5VSB rails. Normaly, each rail has two caps. Sometimes I am lazy or don't have enough caps, so I replace only one of the two caps on each rail.

The caps to replace in your PSU are the larger caps you see in your 1st, 2nd, and 3rd pictures you posted. The smaller caps don't need to be replaced (exception to the rule here are any "critical" 5VSB circuit caps, but I don't think your PSU has that design). Follow the wires for the 3.3V (orange), 5V (red), and 12V (yellow) rails on the solder side of the power supply, and you should be able to figure what caps belong to which rail. A multimeter with continuity/beeper function can also help if you are new to this. If a cap belongs to a certain rail, then the lead on its positive (+) side of that cap will beep/show continuity to the rail it is on. Let me know if you need more explanation here.

As for the two very large 200V caps - those don't need to be replaced.

You don't have to remove the heatsinks to access the caps. Just pull the old caps with fingers or tweezers. Work yourself from the outside in.

Another option is to buy a new PSU but the problem is none of the modern PSU has a -5v rail.

You can make your own -5V rail from the -12V rail with a 7905 voltage regulator and two caps. But as I said above, your current PSU looks good, so you don't really need to buy a new PSU. I think your problem may be elsewhere.

I tried a couple of them which has got no -5v rail, and the motherboard does not boot up. The only way to boot up is to have an old PSU that has -5v rail.

Like I said, you have an ISA slot. Most mobo's with that need a -5V rail.

[liukuohao]

Re: Replace bad caps with Panasonic caps

It might be preferable to just purchase a new PSU, because it might end up costing the same.

Hi mockingbird,

Thank you for your response.
But replacing a new PSU will not be an option for me if I want to run
my P3 motherboard, because it requires -5v to boot up. Without it,
the -5v rail ( I know it is for the old ISA slot, even though I don't use it)
I am afraid, I just cannot fire up the motherboard.

Unless, like momaka mentioned build your own -5v rail using -12 rail
by building a voltage regulator chip, which I have no such idea unless there
is circuit diagram.

[momaka]

Re: Replace bad caps with Panasonic caps

If you Google "7905" and open the datasheet from TI (Texas Instruments), you will see a typical application circuit right on the first page. But I am giving you this just for information. Like I mentioned in my previous post, I think your PSU looks fine. The CapXon caps may or may not be bad. But if you want a 100% reliable and trustworthy PSU, then recap it with Japanese caps.