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SE/30 Zebra Strip

belgaonkar

Well-known member
I recently got an SE/30 in a giant lot of Macs for $100 from a older gentleman. This specific SE/30 has 32MB of RAM and a 50MHZ Diimo 030 accelerator. After speaking to him, he apparently developed a couple of programs for the SE/30 and so the upgrades were justified. When I powered it up, a flashing floppy drive appeared. I went to go change the hard drive and replaced it with a 500MB drive with a 7.5 install on it. After re assembly, the machine gave a zebra striped pattern. Disassembled it, and found that two caps had fallen off. I am wondering what the exact part numbers are of the caps are and how easy it is to fix. I can solder, but have never re capped a board before. 

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joethezombie

Well-known member
It is imperative that you recap the board.  The capacitors leak and will dissolve the traces near and under them.  This has already started to happen, as the legs of the existing capacitors have dissolved, causing them to fall off.  I would imagine you have some trace damage.  Probably not completely compromised, but likely the surface has started to corrode, so look closely with magnification.   I use solid polymer versions so that they will never leak again.  They are more expensive, but in the long run, I say worth it.   https://www.digikey.com/product-detail/en/nichicon/PCV1D470MCL1GS/493-4369-1-ND/

One of the capacitors is a smaller part, not available in solid polymer.  I use https://www.digikey.com/product-detail/en/panasonic-electronic-components/EEE-HD1H1R0R/PCE4972CT-ND

I remove the capacitors with hot air.  Protect any nearby plastics with Polyimide tape, or another heat reflective material (foil can get you by in a pinch).  Practice safe ESD procedures.  A wrist strap connected to the board is adequate.  A fully grounded work mat is better.  After removal, use desolder braid and flux to remove the old solder from the pads, then clean thoroughly with 99% alcohol.  Finally, re-tin the pads before cleaning the entire board.

Just as important as recapping is making sure to clean the board of all the capacitor dielectric after removing the capacitors.  You must make sure you get all of it off, especially around the UE8 area.  Don't be afraid of white vinegar and a toothbrush.  Rinse well with distilled water, followed by a 99% alcohol rinse.  Blow dry with compressed air.  Afterwords,  I bake mine at 120deg for 15 minutes.

Now, install the new capacitors, taking care to note polarity.  There are lots of tutorials on youtube you can watch if you've never done this before.

I would say it's pretty darn easy, especially If you have previous soldering experience.  The hardest part is the removal process, which is elementary with a hot air station.

EDIT:  On a side note, congrats on the DiiMo.  They're pretty hard to come by these days.  If you are looking to sell it, PM me!   :D

 
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belgaonkar

Well-known member
Thanks. When you said more expensive, I was expecting it to be $10 a pop. I had no idea the caps are so cheap, even at $1.20.

Sidenote: Ive got two Diimo 030's. Might be willing to let one go, ill PM you!

 
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ScutBoy

Well-known member
BTW - Trag here on 68kmla sells "kits" of the caps necessary for the SE/30 logic boards. I've done two boards with them, and have 3-4 more on the way.

I agree that hot air works well to remove the old caps, but I've also used side cutters to cut the little cans, and then pull up the plastic base afterwards. You then need to use an iron to remove the remnants of the legs on the pads, but that method works well if you don't have hot air available.

Do NOT skip the washing step after you remove the old caps - especially if you use the cutoff method. Make sure you get all the gunk off the board, especially around UE8, where there's a group of 4 caps - three the same and one smaller - which all leak around UE8 and it's friends.

I approached my first recap with some trepidation, since I solder like I have two left hands, but if you take your time it will come out fine. There's very few errors you can't fix.

 

belgaonkar

Well-known member
I emailed him, but haven't gotten a response back :( Ill probably just order the specific parts if I don't get a response back in a few days. 

 

Boctor

Well-known member
BTW - Trag here on 68kmla sells "kits" of the caps necessary for the SE/30 logic boards. I've done two boards with them, and have 3-4 more on the way.

I agree that hot air works well to remove the old caps, but I've also used side cutters to cut the little cans, and then pull up the plastic base afterwards. You then need to use an iron to remove the remnants of the legs on the pads, but that method works well if you don't have hot air available.

Do NOT skip the washing step after you remove the old caps - especially if you use the cutoff method. Make sure you get all the gunk off the board, especially around UE8, where there's a group of 4 caps - three the same and one smaller - which all leak around UE8 and it's friends.

I approached my first recap with some trepidation, since I solder like I have two left hands, but if you take your time it will come out fine. There's very few errors you can't fix.
About the gunk on the board, I can't emphasize how much I agree about its importance. I got all of the visible corrosive stuff off after I removed the old caps about a year ago, but there was still grime hiding under ICs and such. The board always needs a good wash and dry with something non-conductive that leaves no residue. I once almost killed mine with 70% isopropyl alcohol and its nasty mineral residue, but a good bath of 91% alcohol and a scrub with an unused toothbrush saved it. Should any solder pads come off (I'm a complete klutz and tore the anode pad for C3 out) the schematics are a huge help.

I wish you luck on buying and attaching the new caps, belgaonkar. I ordered all mine from retailers on Amazon, and they're still working correctly. Make sure they're the right dimensions to fit on the pads, though.

 

belgaonkar

Well-known member
Got the caps today.

What do you mean by cut off? Just take some angle cutters and pull up? The plastic pieces don't have enough clearance to cut the caps off.

Tried finding a video, but there isn't one specifically on the recapping the lobo for an SE/30

The Mac also came with the original manuals and paperwork. I was skimming through and found the original purchase receipt and paper working showing the analog board was replaced within the past 15 years. Its probably due for a recap too, but it works, so its not a priority.

 

SlateBlue

Well-known member
You cut above the plastic, then carefully remove the cap remnant and plastic base. Don't pull up on the entire cap as you cut because you'll risk lifting a pad.

 

dochilli

Well-known member
Here you can see the cutting process:

http://appletothecore.me/files/leaky_caps.php

I used this for all my recapped mainboards and had no solder pad that came off. But you must be carefull when you take the metal cup off the board. Cut ist allways above the plastic base! The plastic can be broken in two parts very easy.

Good luck!

 

hunter44102

Well-known member
No cutting needed. I removed all the caps just by gently wiggling the metal head till it breaks off. Then either slide off the black plastic or gently bend the remaining leads till they break off.

You then use solder wick to pick up the remaining leads and solder on the pads.

I didn't have a single issue doing it this way

 

SlateBlue

Well-known member
No cutting needed. I removed all the caps just by gently wiggling the metal head till it breaks off. Then either slide off the black plastic or gently bend the remaining leads till they break off.

You then use solder wick to pick up the remaining leads and solder on the pads.

I didn't have a single issue doing it this way
That's a good way to stress the solder pads. I'm thinking you got lucky.
 

Boctor

Well-known member
That's a good way to stress the solder pads. I'm thinking you got lucky.
I just used that method on an IIsi, before desoldering the slightly-corroded remains of the capacitors' legs. I forgot where I first heard it from, but it was emphasized to steadily twist left or right on the capacitor without pulling on it. I'm personally afraid to cut many things, at risk of damaging the neighboring components in a logic board's more crowded areas.

 
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