VOGONS


First post, by X3J11

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I recently bought a "new"/unused KT7A-RAID v1 motherboard as a present for myself for my birthday. It was one of the many bits of hardware I've owned in years gone that I thoughtlessly discarded long ago, and which I've sought to reacquire. It's kind of been my holy grail motherboard straddling the DOS/98 to XP days.

Now before I even think of plugging it in, I'd like to recap the board. However, I'm largely ignorant of the subject, and am looking for advice on what capacitors I should use. My Googling has led to years old posts discussing capacitor series that have long since been discontinued.

Browsing through DigiKey's site is overwhelming when one doesn't know exactly what they're looking for. Does anyone have any suggestions for what series of electrolytic caps one would use for fixing up a board nowadays? And what would one use for the Low ESR marked caps; my understanding it that they're not all that common any more as manufacturers switched to polymers (which, from what I gather, are not ideal for boards of this vintage).

Reply 1 of 11, by PcBytes

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These are the well known brands I know I use for recapping, depending on availability:

- Nichicon HM/HN
- Rubycon MBZ and ZL
- Chemicon KZE
- Panasonic FL

"Enter at your own peril, past the bolted door..."
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Reply 2 of 11, by X3J11

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PcBytes wrote on 2023-02-23, 19:34:
These are the well known brands I know I use for recapping, depending on availability: […]
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These are the well known brands I know I use for recapping, depending on availability:

- Nichicon HM/HN
- Rubycon MBZ and ZL
- Chemicon KZE
- Panasonic FL

Fantastic, thank you! Of them, I know Ruby and Pana are generally held in high regard. Do you have a preference, or are they all of equal reputation?

Reply 3 of 11, by cde

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I think I used Rubycon+Panasonic when I recapped my KT7A in 2020, but it was mainly a matter of what was available on digikey at the time. Obviously you want low ESR and the same footprint/capacity. After removing the old ones and testing them at least 1/3 were defective.

Reply 4 of 11, by cyclone3d

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You should power on the board before recapping.

Just be sure to not have yourself of anybody else in line with the capacitors.

I did that a few years ago and multiple capacitors exploded and scared me pretty good.

There was paper bits plastered to the surface that was closest to the top of the board.

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Reply 6 of 11, by cyclone3d

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I wasn't being serious.
In any case, the one I bought was also a brand new KT7A.
Looked perfectly fine.
Powered it up and it sounded like a few .22 bullets were fired right next to me.

Yamaha modified setupds and drivers
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Aopen AW744L II SB-LINK

Reply 8 of 11, by X3J11

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cde wrote on 2023-02-24, 00:47:

Cyclone3d, I think doing so you risk causing a short and irreversibly damaging a hard to repair component like the VIA686.

cyclone3d wrote on 2023-02-24, 04:42:
I wasn't being serious. In any case, the one I bought was also a brand new KT7A. Looked perfectly fine. Powered it up and it sou […]
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I wasn't being serious.
In any case, the one I bought was also a brand new KT7A.
Looked perfectly fine.
Powered it up and it sounded like a few .22 bullets were fired right next to me.

I figured you were joking. I had one cap blow on a video card I was testing, that was enough for me. The pop and puff of smoke were fascinating, but it's not something I'd like to repeat.

stanwebber wrote on 2023-02-24, 05:36:

badcaps.net is a resource i've used in the past.

I actually was motivated to attempt to do it myself thanks to badcaps. Unfortunately the online store was recently shut down, so no more premade kits from them, and all the discontinued cap series I mentioned came largely from posts to their forum.

I just don't know what to do about the low ESR caps down near the PCI slots. Are modern caps good enough that all I need worry about is matching the capacitance, voltage, and physical characteristics? Or is there a particular series of modern caps that is better suited for replacing low ESR?

Reply 9 of 11, by PcBytes

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X3J11 wrote on 2023-02-24, 12:18:

I just don't know what to do about the low ESR caps down near the PCI slots. Are modern caps good enough that all I need worry about is matching the capacitance, voltage, and physical characteristics? Or is there a particular series of modern caps that is better suited for replacing low ESR?

I've looked at the mobo over some pictures from Vogons (cde's mainboard to be exact) and I could notice they (ABIT) mixed the diameters starting from the AGP slot downwards.

I'd suggest 1000uF 6.3v on all points from AGP below. Even if there are 1500uF - I've successfully used 1000s in place of 1500uFs on other mainboards, as long as they were after the AGP slot downwards - they don't see as much stress as other zones of a mainboard - hence why you can go 1000/6.3v safely starting from the AGP slot downwards.

You can also go with 10v caps, as long as they're the same height as the caps you're replacing.

"Enter at your own peril, past the bolted door..."
Main PC: i5 3470, GB B75M-D3H, 16GB RAM, 2x1TB
98SE : P3 650, Soyo SY-6BA+IV, 384MB RAM, 80GB

Reply 10 of 11, by watson

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I fully recapped a KT7-RAID (without the A) several weeks ago.
I used all Panasonic FR capacitors except for three 1500uF/6.3V caps near the AGP slot because the FRs are too tall - 16mm height is required.

Here is a list of exact part numbers:
2200uF/10V (4x) - EEUFR1A222L
2200uF/6.3V (9x) - EEUFR0J222
1500uf/6.3V (4x, 10 mm diameter, 16 mm height) - EEUFR1A152 (I used a 10V cap because it has the same footprint, obviously you can use a 6.3V rated cap)
1500uF/6.3V (3x, 8 mm diameter, 16 mm height, near AGP slot) - Rubycon 6.3ZLQ1500MEFC8X16
1000uF/16V (4x) - EEUFR1C102
1000uF/10V (5x) - EEUFR1A102L
100uF/16V (4x) - EEUFR1C101

Of course, I would recommend you to make a list of caps that are on your board and confirm it matches mine before ordering anything.

As already stated, the original caps are junk (Jackon on my board) and in this case, I think a full recap is worth it.
Here is also a relevant thread on Badcaps: https://www.badcaps.net/forum/showthread.php?t=267

Reply 11 of 11, by X3J11

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watson wrote on 2023-02-24, 21:51:

I fully recapped a KT7-RAID (without the A) several weeks ago.
I used all Panasonic FR capacitors except for three 1500uF/6.3V caps near the AGP slot because the FRs are too tall - 16mm height is required.
(Remainder omitted for brevity)

This is perfect, thank you! I've already taken a photo of the board and begun marking what's what on it, though it is a tedious process (my eyes are terrible, I've been nearsighted since forever, and now even that's going for a dump). Next up is to mark the polarity, just in case, and with a recently purchased head magnifier go over it more thoroughly.

Mine also has Jackcon; I don't believe the caps or board layout changes much between the non-A to A, but I'm not certain. Either way, knowing what series of caps are acceptable was my primary concern.

I have several boards on the to do list, and have a few of lesser importance to practice on first.

Gratitude to everyone here for their assistance, it is greatly appreciated!