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Powerbook recap ; size & brands ?

Cedsrepairs

Member
Hello,

I've got a few powerbooks to recap,
- a PB100 that "somewhat boots" but screams for a recap (every 1uF on the board leaked!)
- a PB180 that works flawlessly, apart from the screen tunneling
- a Duo 270c that does not boot.

I've recapped older things (Apple II plus, Apple IIc) but never SMD laptops.

From my initial readings and findings

- it seems logical to me to replace the SMT electrolytics with Tantalums, at least where they are obviously used as filtering. (I wouldn't do that in a power stage.)
- the footprint of round SM electrolytics vs rectangle tantalum differ very much, tantalum ssem to come in 6mm and 3.2 mm length
- there are at least 3 brands for tantalums on farnell

Would anyone please share some insights or experience on good brands, on proper sizes to order, etc ?

Is there like a size chart ? It seems to me 6mm tantalum match >10uF SMT, and 3.2 mm size match smaller electrolytics (like 1uF)

I plan to order KEMET brand, size 2312 ( 6032 metric : meaning 6.0mm by 3.3 mm) serie T491
they've got "low esr" and "regular esr", i plan to use "regular esr" (2.2ohms) as low esr in 2021 is probably "insanely low esr" for 1989 vintage computers.

Anyway anything you could share on the topic would be welcome,
 

desertrout

Well-known member
Sounds to me like you're on the right track. I use 1411's (3.5mm x 2.8mm) for the 1uF's and 10uF's, 2312 for the 4.7uF (could have been smaller), and use aluminum polymers for the 47uF/16's (5.3mmx5.3mm), but you could use 2312 tants of course. Kemet's are known good, but I think you'll be fine with just about anything you get from a reputable seller - like AVX or Vishay. As for ESR, I don't fuss except on PSU's, where low ESR and higher temp ratings matter more.

I trust you're doing all the radials too? Just try to match dimensions / lead spacing as closely as you can.

I also recap the 100 display - there are eight 3.3uF/35V surface mounted radials that I find are usually crusty. Smaller the better as they fold over.

Nothing to recap on the 180 logic boards.

Don't forget the radials on the inverter boards - they leak as well.

I have no experience with Duos... I don't plan on it. Just not my thing for some reason.
 

Cedsrepairs

Member
thanks, at least I know I go in the right direction,

I've just opened the display on the PB100 (which isnt super easy) but I fail to see the 8 caps, are they hidden like behind the display ?

I did see two electrolytics on the inverter board but in my case, they do not seem leaky. I'll of course replace them anyway, I don't want to be back in there.
Speaking of the inverter board ; could you confirm (if you recall) one of them - the smallest - is a 15uF/16v ? Because it's unreadable on mine, but that's what it looks like...

Why do you say there's nothing to recap on a pb180 ? (I've not opened it yet, especially as it works) ?
 

desertrout

Well-known member
Yup the caps on the 100 display are on the reverse. Check this post here for an illustration: https://goughlui.com/2016/09/24/repair-apple-macintosh-powerbook-100-gotta-re-cap-em-all/ --- this fellow used tantalum radials, but I use electrolytic, I find they fit better.

For the inverter... that site above actually has a cap list further down, and suggests that smaller one is indeed a 15uF/16V, and looking at my old Digikey carts that does appear correct.

Keep in mind that just because the caps aren't leaking doesn't mean they're still good. Besides, they're old and really ought to be replaced anyway. For a few cents and a couple of minutes, it's worth doing. (fwiw, for some reason, every inverter cap I've replaced has been leaky)

The only thing to recap on the 180 is the inverter board and I suppose the trackball if you really wanted to be thorough (they always test good when I remove them). There are no electrolytic caps on the logic boards or the display. I suppose the only other thing to look at in there is the PRAM battery, which despite being a lithium coin can still get crusty. You can replace it (VL-2330), or simply remove it.
 

Cedsrepairs

Member
Thanks for your time @desertrout ! I've also used your signature style as I found it cool and useful :)

I'll finish my Farnell cart ( similar to digikey over here in europe ) , wait for the parts, and get going.

I'm also retrobrighting the PB100 by the way, a process I've already tried on a couple of grey items (apple floppys, mice) -.
The unit is not yellowed (as it was never white), it's "greened", but the retrobright process works on grey items. However, you have to be very cautions as you can end up with something with spots, stains, stripes, or even complete camo style...
 

desertrout

Well-known member
I hope it all works out well!

I've never tried retrobrighting grey items myself, though I have a couple of keyboards that are definitely 'brown' or discoloured. I'll have to give it a shot!
 

Cedsrepairs

Member
Little update,

Every 10uF SMD and every 1uF SMD leaked (frosty joints, brown residue), strangely enough every 47uF looked fine. I'll replace everything.
ced_2021-09-28@18h48_IMG_5106.JPG


My Victims
ced_2021-09-28@23h57_IMG_5133.JPG

Work in progress
ced_2021-09-29@14h17_IMG_5136.JPG
 
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Cedsrepairs

Member
Some of the difficulties

- Most non SMD electrolytics are actually low profile models, I'm not sure regular models will fit. Thru hole tantalum are too high. I just ordered new low profiles ones.

- This is especially true in the lcd inverter board, which has very little clearance. Looks impossible to me to put a tantalum in there, despite what the web blog says. Waiting for new parts here as well.

- Strangely enough, not only did the 1uF on the CPU board leak, but I got severe leakage of the 10uF on the trackball board.

- The board has a weird coating on the back side, same for the inverter board. This coating is sticky (maybe due to age ?), and seems to dissolve with 99% alcohol's vapors - making it even more sticky - which doesn't help cleaning. I removed the coating entirely on the inverter (small surface) but left it on the mainboard, even if it's partially sticky.
 
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Cedsrepairs

Member
Wow recapping the screen of a PB100 is not for the faint of heart.

ced_2021-10-02@11h59_IMG_5167.JPGced_2021-10-02@12h59_IMG_5172.JPGced_2021-10-02@15h36_IMG_5184.JPG

I chose to put electrolytics again as they are the only ones that fit.

I was unable to remove the white plastic, I just cut a bit of it to make the repair easier.

This recap is the most difficult I've ever done.
 

desertrout

Well-known member
Looks good. I don't remove the plastic either, but I 'fold' the legs over like the originals - your solution may be easier. It's tight work to be sure, makes me think I probably would have done reasonably well as a surgeon 😄
 

Cedsrepairs

Member
There is a small zone right in the middle of the lcd that is weird ; it looks like a space invader made of pixels that appear purple or blue depending on the angle ( screen turned off )
I guess this is no good news ; is that kind of an lcd leak of sort ? It’s currently very small but I guess it will expand …
 

desertrout

Well-known member
It's delamination / leakage likely due to physical damage to the screen, often in the area of where the screen meets the trackball when closed. I've had this on a couple screens, including a 100, but it doesn't get worse (or better) in my experience. It's not repairable afaik, but if the spot is small enough you usually don't notice it much.

Because of this, I don't close my 1xx PB's fully or I remove the trackball if I need to.
 

Cedsrepairs

Member
Little update

I’ve now entirely recapped both motherboard and screen and put it back together

it works ; it doesn’t make the horrible « caps are burning « sound it use to do
I’ve booted on floppy and all goes well

but … indeed the screen has a problem ( as you said where the mouse hits ) some pixels are dead in the zone and look red… and … worse than that … it seems I ruined it with ipa alcohol which got inside the lcd panel while I was cleaning the caps junk on the lcd ;(
I’ve tried to dry it but it doesn’t seem to work

this is is freaking frustrating ; the thing is literally back from the dead … working like a champ .. and I have an horrible screen with a big stain of liquid that’s my fault :(

Like each time my repairs don’t go as planned I’m tempted to find another hobby and throw it thru the window …

anyway wanted to share :)
 

desertrout

Well-known member
Ah, sorry to hear it. I once was a bit over-eager with the IPA near the drivers on one side of a 160 display and ended up causing it to delaminate, causing annoying vertical lines to appear on that half of the screen... so I feel your pain.

Between tunneling, delamination, dead pixels, and screen rot, a fully working display on a 1xx PB is getting rarer and rarer.
 

Cedsrepairs

Member
i'll tear it apart tomorrow and try to find where the liquid resides. I have a small hope it's just between the alumium foil at the back and the glass panel ( as I don't see the stain moving when I poke at the screen). If it's there, it should be relatively easy to wipe.

If it's indeed inside the LCD panel itself, I don't think I can get it out (the hairdryer made no change)

If I can"t fix it i'll probably start looking from a "for parts" PB100, as I hate to end a repair like this :)


Do the PB100 also suffer tunneling ? I have a PB180 with tunneling (after say 20+ minutes the corner become dark) so it's "usable", it's not like I would be working 8 hours on it :)

I have to say laptops are way more difficult and frustrating to repair than desktops, or older systems, which are all robust, using off the shelf parts, and can resist quite a lot of beating.
 

desertrout

Well-known member
Do the PB100 also suffer tunneling ?
Actually, no as it's a passive-matrix display -- it appears only the active-matrix displays suffer from this, like on the 170 and 180.

There is reputedly a fix (at least temporary) for tunneling that involves baking it:

 

Cedsrepairs

Member
I’ve read those theories but I find that if they are true ; the fix must be incomplete

I can admit that this may be due to moisture ; but for me it makes no sense to heat the thing in the oven without , later , preventing the moisture back in ( like by sealing the edge or something similar )
 
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