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End of design life - capacitor refurbishment required!
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t-rexky



Joined: 09 Jan 2011
Posts: 292
Location: Snowy Canada

PostPosted: Mon Feb 28, 2011 8:13 am    Post subject: End of design life - capacitor refurbishment required! Reply with quote

Unfortunately this is not a joke Sad

I recently resurrected my Turbo Color station and spent a considerable amount of time and money getting it into a good shape. I bought RAM, hard disks, LCD monitor and even a spare "just in case" Turbo Color from Rob at BlackHole.

Got my unit finally all set-up and was in the process of tidying up the "computer museum" room when I noticed something quite alarming. The lighting was just right to show a stain around one of the electrolytic capacitors on the "spare" motherboard. Upon closer inspection it appears that all of the capacitors have vented with 1 to 1.5 inch stains around them and even leakage through the board vias to the opposite (lower) side. I then pulled my original station apart once again and noticed that the capacitors started venting electrolyte as well, although not as badly. So it looks like the capacitors are at the end of their design life.

I spent a number of hours online yesterday cross-referencing varios component suppliers and I ordered a full set of replacement electrolytic capacitors for both of my stations, two sound boxes and both power supplies. For anyone else crazy enough to consider reworking their slab, I can provide the list of parts that I ordered from DigiKey. I will post some updates with the outcome of the surgery.


Last edited by t-rexky on Tue Jun 21, 2011 8:03 am; edited 1 time in total
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pentium



Joined: 23 Jun 2006
Posts: 1160
Location: Kamloops, BC

PostPosted: Mon Feb 28, 2011 10:56 am    Post subject: Reply with quote

This was not unexpected. It's been happening to Macs for years now. Thankfully as you mentioned it's easy to repair the problem.
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cubist



Joined: 20 Sep 2007
Posts: 251
Location: Cambridge, MA

PostPosted: Tue Mar 01, 2011 9:27 pm    Post subject: Re: Warning: black hardware reaching the end of its useful l Reply with quote

t-rexky wrote:
I will post some updates with the outcome of the surgery.


Please do! (Part Nos, inexpensive surface-mount station, etc....) I've posted here of evidence of caps problems developing on one of my NextDimension boards. We're going to have to start developing conservation skills, I'm afraid.
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t-rexky



Joined: 09 Jan 2011
Posts: 292
Location: Snowy Canada

PostPosted: Wed Mar 02, 2011 5:40 am    Post subject: Reply with quote

pentium wrote:
This was not unexpected. It's been happening to Macs for years now. Thankfully as you mentioned it's easy to repair the problem.


Yes, I am actually surprised that they lasted this long. It is a nice evidence of the component quality that NeXT were using in their designs...

cubist wrote:
t-rexky wrote:
I will post some updates with the outcome of the surgery.


Please do! (Part Nos, inexpensive surface-mount station, etc....) I've posted here of evidence of caps problems developing on one of my NextDimension boards. We're going to have to start developing conservation skills, I'm afraid.


So slab number one is done and happily purring on my bench in the basement. When I complete machine number two I will put together a complete walk-through, but I do have to warn that very good soldering skills are required to do this.

A few quick observations:

The power supply, as others indicated before, is simply INSANE to repair because of its design. I though I was doing extremely well, until I attempted to replace a small 22uf surface mount capacitor installed on the base plate. I ended up putting the whole aluminum base plate on an active cooktop element to preheat it, and even then my 60W solder station would not melt the solder long enough to properly remove it. I ended-up cutting the capacitor out. Installing a surface mount replacement capacitor is effectively impossible, so I had to improvise. Not pretty, but it works. But this is not the worst part! There is a daughter board in the power supply that is connected to the main board (and the aluminum plate) with a number of conductive posts. One of these posts let go off the base plate some time during the rework. Let's just say that I had to use a plumber's propane torch to have it reattached Exclamation (at that point I figured I had nothing to lose). In all of that insanity I somehow DID NOT overheat the components and the PSU still appears to work just fine! But I don't trust it in the long run so I'll be getting a replacement unit and will rework it slightly differently.

The good news is that the main board of the station is a breeze to repair in comparison. I worked very carefully and it took approximately 2 hours. There are three thru-hole capacitors and eight surface mounted capacitors. The biggest challenge was to clean up the released electrolyte from the board and from the solder pads. The fact that NeXT designed really nice and large solder pads for the capacitors is great help. In the end I don't think anyone could tell that the board was reworked - all the capacitors look factory installed.

I'm going to get a few more parts from Digi-Key, including a much more powerful solder iron, and will have a go at the second station. I will document it with photographs and will eventually post an illustrated walk through with the parts list.
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macsimski



Joined: 10 Jun 2007
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Location: Amsterdam, the Netherlands

PostPosted: Tue Mar 29, 2011 6:59 am    Post subject: Reply with quote

removing old surface mount capacitors is easy, grip the aluminium part with a small vise and gently turn them without pulling. het wires will go loose inside and there is plenty of room left afterwards to clean the solderpads. test it on a broken pc board. works like a charm
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t-rexky



Joined: 09 Jan 2011
Posts: 292
Location: Snowy Canada

PostPosted: Thu Mar 31, 2011 8:33 am    Post subject: Reply with quote

macsimski wrote:
removing old surface mount capacitors is easy, grip the aluminium part with a small vise and gently turn them without pulling. het wires will go loose inside and there is plenty of room left afterwards to clean the solderpads. test it on a broken pc board. works like a charm


That's what I had to do with the single power supply surface mount electrolytic. On the main boards though I did not want to risk any damage to the solder pads. Particularly since I read in some other posts that some of the main board pads lifted quite easily. I'm still planning on posting a walk-through at some point for anyone wanting to do the same repair.
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tomaz



Joined: 15 Apr 2006
Posts: 150
Location: Sark

PostPosted: Sat Apr 02, 2011 2:22 pm    Post subject: Reply with quote

Has anyone experienced specific negative consequences of switching on a machine which contains failed capacitors, or a capacitor failing while it is running?
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t-rexky



Joined: 09 Jan 2011
Posts: 292
Location: Snowy Canada

PostPosted: Sat Apr 02, 2011 2:35 pm    Post subject: Reply with quote

tomaz wrote:
Has anyone experienced specific negative consequences of switching on a machine which contains failed capacitors, or a capacitor failing while it is running?


No direct experience, but degraded capacitors will greatly increase the noise on the power supply lines on the motherboard. That could lead to stability problems, random kernel panics, etc. Degraded power supply capacitors, particularly the input filter capacitor, can lead to catastrophic component failures in the power supply, such as the switching MOSFETS, and could propagate to motherboard component failures.

The two motherboards and four power supplies that I have reworked have been all 100% stable over many hours of burn-in testing. After I am all done with this I will probably have a few extra reworked power supplies that I could sell, if anyone is interested. I would not volunteer to rework anyone's motherboards as it is truly "labour of love" that is very time consuming. High quality capacitors are not that cheap either...
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macsimski



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PostPosted: Sun Apr 03, 2011 1:10 am    Post subject: Reply with quote

on both macs and nexts sound will be distorted or abcent. that is a indication that the caps are going. most of the time the capacitors loose their capacity.
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Rob Blessin Black Hole
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Joined: 05 Sep 2006
Posts: 719
Location: Ft. Collins, Colorado

PostPosted: Sun May 08, 2011 11:03 pm    Post subject: Re: Warning: black hardware reaching the end of its useful l Reply with quote

Hello : I thought I would let everybody know , I actually built a cement vault storage area in my basement as part of my preservation/ conservation efforts to preserve and maintain as much of this NeXT hardware for as long as possible a few years back. Also make sure it is dry, I actually love these little computers ; call me crazy , I know i'm not alone but if capacitors need to be replaced eventually thank you for the advice we'll probably do it along with everyone else and so your advice in this respect is much appreciated . I know I've ordered from digikey before I'm hoping that one of these will boot in 2088 .
I'm thinking I'll go through the stacks of NeXT periodically to make sure they boot and let em run for awhile as letting them sit after consulting with my dad today, he's repaired many TV's in his day including the old tube types and has helped me with the business over the years may contribute to the capacitors failing!
I know a lot of hearts are in this that's why I've stayed with it for so long!

Hope this finds you all well, if you need NeXT stuff let me know, if I don't have it or don't have the answer I'll be glad to help you find someone that can help!
I've noticed a lot of floppy disk failures because of age but we are trying to keep the dream alive, amazing all these years and am still happy doing this when the NeXT business is fast or slow it is still pretty cool.

BesT Regards Rob Blessin


t-rexky wrote:
Unfortunately this is not a joke Sad

I recently resurrected my Turbo Color station and spent a considerable amount of time and money getting it into a good shape. I bought RAM, hard disks, LCD monitor and even a spare "just in case" Turbo Color from Rob at BlackHole.

Got my unit finally all set-up and was in the process of tidying up the "computer museum" room when I noticed something quite alarming. The lighting was just right to show a stain around one of the electrolytic capacitors on the "spare" motherboard. Upon closer inspection it appears that all of the capacitors have vented with 1 to 1.5 inch stains around them and even leakage through the board vias to the opposite (lower) side. I then pulled my original station apart once again and noticed that the capacitors started venting electrolyte as well, although not as badly. So it looks like the capacitors are at the end of their design life.

I spent a number of hours online yesterday cross-referencing varios component suppliers and I ordered a full set of replacement electrolytic capacitors for both of my stations, two sound boxes and both power supplies. For anyone else crazy enough to consider reworking their slab, I can provide the list of parts that I ordered from DigiKey. I will post some updates with the outcome of the surgery.
Wink
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t-rexky



Joined: 09 Jan 2011
Posts: 292
Location: Snowy Canada

PostPosted: Tue Jun 21, 2011 8:26 am    Post subject: Reply with quote

Hi Rob,

Good to hear from you! I would like to add that all the stuff that I ever got from you has worked very well, so obviously your conservation efforts are paying off! Powering the hardware on once in a while is a very good measure to keep the capacitors refreshed (formed). Here is an interesting link regarding capacitor replacement on old/obsolete equipment: http://www.nmr.mgh.harvard.edu/~reese/electrolytics/ . Thankfully we do not have to go to such extremes with the NeXT equipment, as there are excellent replacements available with the same form, fit and function. NB, I too want to keep running my NeXT hardware for the next 20 or 30 years, assuming that I am going to be around that long myself Smile...

I have been putting together a walk through for capacitor replacement on the Stations whenever my free time allowes. I am pretty far along, but not quite finished yet. I will submit it here once finished, so that everyone else can benefit from it. I reworked two stations and four power supplies so far, and everything is working perfectly. The stations are actually quite easy to re-cap. The power supplies are another story all together - as I mentioned in one of my previous posts I had the plumber's torch out (twice) already 'Shocked' I will attempt a power supply walk through as well, but with a big disclaimer that I'm not responsible for the outcome.

With good replacement capacitors our beloved hardware should have another 20 to 30 years in it!

T-R

Rob Blessin Black Hole wrote:
Hello : I thought I would let everybody know , I actually built a cement vault storage area in my basement as part of my preservation/ conservation efforts to preserve and maintain as much of this NeXT hardware for as long as possible a few years back. Also make sure it is dry, I actually love these little computers ; call me crazy , I know i'm not alone but if capacitors need to be replaced eventually thank you for the advice we'll probably do it along with everyone else and so your advice in this respect is much appreciated . I know I've ordered from digikey before I'm hoping that one of these will boot in 2088 .
I'm thinking I'll go through the stacks of NeXT periodically to make sure they boot and let em run for awhile as letting them sit after consulting with my dad today, he's repaired many TV's in his day including the old tube types and has helped me with the business over the years may contribute to the capacitors failing!
I know a lot of hearts are in this that's why I've stayed with it for so long!

Hope this finds you all well, if you need NeXT stuff let me know, if I don't have it or don't have the answer I'll be glad to help you find someone that can help!
I've noticed a lot of floppy disk failures because of age but we are trying to keep the dream alive, amazing all these years and am still happy doing this when the NeXT business is fast or slow it is still pretty cool.

BesT Regards Rob Blessin

Wink
Shocked
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t-rexky



Joined: 09 Jan 2011
Posts: 292
Location: Snowy Canada

PostPosted: Wed Feb 29, 2012 4:19 pm    Post subject: Capacitor replacement visual walk-through Reply with quote

The walk-through document that I have been working on is progressing at snail's pace, so in the interim I placed some photos on flickr:

http://www.flickr.com/photos/t-rexky/sets/72157629119029226/

I will submit the document once it's done, but it will still take some time...
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gtnicol



Joined: 27 Dec 2005
Posts: 533
Location: Rhode Island, USA

PostPosted: Wed Feb 29, 2012 5:50 pm    Post subject: Reply with quote

I have a fair number of new slab power supplies (kept in a climate controlled environment)... but obviously, they might have capacitor issues just because of age.

On at least one of the MO drives I fixed, replacing capacitors was a big part of it.
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mikeboss



Joined: 07 Dec 2011
Posts: 376
Location: switzerland

PostPosted: Thu Mar 01, 2012 1:33 am    Post subject: Reply with quote

I checked my monoturbo slab main logicboard and it seems to be pretty bad... electrolyte everywhere Confused

@t-rexky: could you post your parts list please? would be very helpful!

thanks,
michael
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t-rexky



Joined: 09 Jan 2011
Posts: 292
Location: Snowy Canada

PostPosted: Thu Mar 01, 2012 6:22 pm    Post subject: Parts list (for TurbColor slab) Reply with quote

Michael, here are the parts that I used:

Surface mount capacitors (Qty. 8 for Turbo Color Slab): 47μF 16V Panasonic FP series (Panasonic EEE-FP1C470AP, DigiKey PCE4530CT-ND). The absolute best choice here would be polymer capacitors, but they are several times the price and probably completely unnecessary. They may also destabilize the power supply due to their extremely low impedance.

Through hole capacitors (Qty. 3 for Turbo Color Slab): 220μF 35V Panasonic FC series (Panasonic EEU-FC1V221, DigiKey P10297-ND). These are high temperature 3000 Hr low impedance capacitors (thatís 3000 hour estimated life at 105įC. I selected 35V rated capacitors as they have the same can size as the originals, longer life and higher ripple current. The Panasonic FM series and Nichicon PW series are also an excellent alternative. Look for 5mm lead spacing to fit the motherboard holes.

For flux I recommend Kester 186 or equivalent, since it is mild enough to be left on after the solder process and it will not cause any damage or corrosion to the components or to the board.


Last edited by t-rexky on Thu Mar 01, 2012 6:42 pm; edited 1 time in total
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