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Old 10 April 2011, 21:42   #1
matthey
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Dave Haynie and SMD caps

Dave Haynie is having a garage sell...

http://www.amiga.org/forums/showthread.php?t=57327
http://shop.ebay.com/?_from=R40&_trk...All-Categories

One of the items he is selling is a revision 2 CD32 with the caps leaking...

http://cgi.ebay.com/Haynies-Garage-C...item1e62d71a68

He mentions...

"I think it's probably seen better days, there seems to be some kind of corrosion around the capacitors, which is weird, since those are aluminum air caps, not something filled with a dielectric goo. But there it is."

The pics look like leaking SMD caps with dust attached to me. This is just another common example of crappy leaking SMD caps from the research I have been doing. I'm about to do a cap and restoration job myself for a 4000, 4000T (amber rev 2 motherboard like the rev 2 CD32) and a CD32 and I really don't like the idea of using crap parts. My 3000s and 3000T with thru holes work fine with no leaking caps (batteries removed). It looks like the only options to avoid the SMD electrolytic caps are to use thru hole electrolytic caps or tantalum caps. Electrolytic thru hole caps look like a good compromise for less leaking/longevity (vs SMD), safety (vs tantalum) and price (vs tantalum). The availability of the thru hole is good for even the smaller sizes where SMD is used on Amigas. Is there any problems or disadvantages with installing thru hole electrolytic capacitors (bending legs and laying across pads) where there is room (everywhere!)? Does this sound reasonable? Has anyone done this also? Would a professional electronic service person frown on me if I asked him to install these?

My buster socket is warped and bulging out and my boards disappear after warmed up on my 4000T (yes, socketed on rev 2) so I want to replace that too. Will this 84 pin SMD plcc socket work?...

http://search.digikey.com/scripts/Dk...me=3M8421B1-ND

Thanks.

P.S. Dave put a NYX AAA motherboard board up too 8-) with battery still intact (Doh!)...

http://cgi.ebay.com/Haynies-Garage-N...item1e62da18bf

Last edited by matthey; 10 April 2011 at 22:42.
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Old 10 April 2011, 22:47   #2
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I'm "watching" the AAA prototype board just to see how much it goes for!
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Old 10 April 2011, 23:02   #3
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yes, I've seen someone using through-hole tantalum in aorg photo gallery (iirc, A4000 audio caps).
it looks professional, dunno if there are some problems.
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Old 11 April 2011, 00:59   #4
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I'm "watching" the AAA prototype board just to see how much it goes for!
I would expect to see $2000-$4000 U.S. because of the documentation and Dave Haynie giving 1/2 to charity. Maybe the same price range as a working 3000+? Non functional and missing the AAA chips hurts a lot. I think there will be a lot of "watchers" though.

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yes, I've seen someone using through-hole tantalum in aorg photo gallery (iirc, A4000 audio caps).
it looks professional, dunno if there are some problems.
I've seen a few tantalum upgrades and I would say the explosion risk is probably overrated if only replacing the smaller caps and non audio caps. I was not planning on doing the caps in tantalum though. The audio caps see negative voltage and should be bi (non) polar electrolytics from what I understand. I was actually wanting to use thru hole electrolytic caps for all replacements and bi-polar electrolytics for the troublesome audio caps. These 22uf 16V bi-polar eloctrolytics look good at a reasonable price...

http://search.digikey.com/scripts/Dk...&name=P1164-ND
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Old 11 April 2011, 01:23   #5
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They look great to me, something I should do on my A4k!
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Old 11 April 2011, 01:31   #6
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Tants are dreadful. Ugh. They have a habit of failing SHORT with age and exploding.

Panasonic capacitors are excellent. Their "FC" series are also great.
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Old 11 April 2011, 02:33   #7
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Tants are dreadful. Ugh. They have a habit of failing SHORT with age and exploding.
Tantalum caps die and explode. SMD electrolytics leak. Why isn't there more people that solder thru hole electrolytics on SMD pads? It seems like the logical solution to me. I have yet to hear from anyone that thinks it is a bad idea. Hmmm .
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Old 11 April 2011, 02:39   #8
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Tantalum caps die and explode. SMD electrolytics leak. Why isn't there more people that solder thru hole electrolytics on SMD pads? It seems like the logical solution to me. I have yet to hear from anyone that thinks it is a bad idea. Hmmm .

I've used through hole caps on SMD pads myself plenty of times. The SMD electrolytics are made exactly the same way, they just dont have plastic covers and they have flat leads which are fed through a plastic base and bent flat.


The Amigas used early generation SMD parts, so I guess design flaws in those parts have long since been corrected. Capacitors have a finite life span anyway, and many Amigas have long exceeded that lifespan.
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Old 11 April 2011, 04:17   #9
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... The SMD electrolytics are made exactly the same way...
They should have been made the same way back then but the SMD caps leaked and the non SMD caps didn't.

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The Amigas used early generation SMD parts, so I guess design flaws in those parts have long since been corrected. Capacitors have a finite life span anyway, and many Amigas have long exceeded that lifespan.
Yea, it could have been that early SMD caps were defective. We won't know if later ones were for awhile. It looks like the new SMD caps are the same design which is what worries me. Another potential problem is that most electronics makers plan on obsolescence in 5 years or less so why would cap manufacturers change the design? I'm not so worried about the caps failing as leaking. Well, thanks for your opinion. That's +1 who thinks modern SMD=thru hole for cap leak resistance. Maybe I should have started a poll. Any one else with an opinion?
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Old 11 April 2011, 06:59   #10
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I think it's more a matter of quality than SMD vs thru-hole. The SMD Panasonics used on (at least) some earlier A4000's usually don't leak, but the cheapies do. (I've yet to see an A600 or Commodore A1200 board with out at least some evidence of leakage.) The thru-hole caps used in the earlier Amigas were generally good quality (Elna, Shoei, Nichicon). I've yet to have an issue with those, but I've seen plenty of cheap thru-hole caps leak, explode, or otherwise fail.

My opinion - keep things original, stick with a quality Japanese SMD cap (Panasonic, Nichicon, UCC) and they will last a very long time.
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Old 11 April 2011, 07:29   #11
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Tantalum caps die and explode. SMD electrolytics leak. Why isn't there more people that solder thru hole electrolytics on SMD pads? It seems like the logical solution to me. I have yet to hear from anyone that thinks it is a bad idea. Hmmm .
I think it's a bad idea, you could knock the cap and rip the pad off the board. Unlikely, but I have seen it happen.
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Old 11 April 2011, 09:01   #12
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yeah, but that could also happen with SMD. though less likely.
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Old 11 April 2011, 11:19   #13
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I don't agree. A properly soldered SMD resistor/capacitor has an incredibly strong mechanical attachment to the board.
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Old 11 April 2011, 12:33   #14
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I don't agree. A properly soldered SMD resistor/capacitor has an incredibly strong mechanical attachment to the board.
Problems usually arise if you use a through hole part and too much heat into the pad. SMD parts do have a very secure mechanical strength to the board but this can also be their weakness, as when the boards are manufactured, if the reflow curve isn't correct for the board it puts too much mechanical stress on mostly the 1206 / 805 / 603 / 402 parts and this can cause micro cracking within the parts themselves. Flexing the board after it's been reflowed and cooled causes similar sorts of problems. One board I used to test had a string of capacitors along one edge and naturally it was snap pressed into a housing, stupid design and multiple field failures.
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Old 12 April 2011, 09:13   #15
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I would expect to see $2000-$4000 U.S. because of the documentation and Dave Haynie giving 1/2 to charity. Maybe the same price range as a working 3000+? Non functional and missing the AAA chips hurts a lot. I think there will be a lot of "watchers" though.

It's the same board as shown on amiga-hardware.com. Albeit with a bit less battery acid leakage!

To quote DH;

"This was the first functional AAA board, and also the first to die. The death was in part purely accidental, and in part a bit of negligence. First to blame is me. Back in those days, you needed +12V for Flash memory, so I had this going to the Flash SIMM modules. Sadly, rather than protect the +12V signal with grounds on either side, or some-such, I pretty much ignored the signal neighbors. This is not the best decision, since a +12V shorted to a normal TTL-level input can destory that input.

Second problem was the ROM SIMM itself. The PCB guys messed up just slightly here, so the SIMM didn't fit tightly in the connector, but could slide left or right a bit. Which allowed adjacent pins to occasionally short out. Fortunately, I noticed this early on, and did not allow a short to occur. Unfortunately, some of the chip designers didn't know about this, and one day tried to start up the board when I wasn't around. The result was a +12V short to data-line D5, killing much of the system. Well, hey, these things happen, and we had two other boards. Those boards went with some of the top chip guys on the AAA project. Far as I know, at least one of those was still functional, or at least as functional as these things got."
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Old 13 April 2011, 12:42   #16
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Prototype amiga/commodore hardware on ebay

There is a load of old Amiga and Commodore prototype hardware for sale from an ex Commodore employee on ebay.

http://shop.ebay.com/?_from=R40&_trk...All-Categories
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Old 13 April 2011, 18:07   #17
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haven't been paying attention?
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Old 13 April 2011, 18:10   #18
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@pcut
haven't been paying attention?
I imagine a Mod moved the post here - probably TCD
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Old 13 April 2011, 20:58   #19
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I imagine a Mod moved the post here - probably TCD
Guilty
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Old 14 April 2011, 15:36   #20
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@matthey

I've replaced leaking SMD caps with mini thru-hole ones on A1200, A4000, A600 & CD32.
No problems at all, just make sure to cut the legs short enough to lower stress to the pads.
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