Unfortunately this is not a joke :(
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.
This was not unexpected. It's been happening to Macs for years now. Thankfully as you mentioned it's easy to repair the problem.
Quote from: "t-rexky"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.
Quote from: "pentium"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...
Quote from: "cubist"Quote from: "t-rexky"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 :!: (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.
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
Quote from: "macsimski"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.
Has anyone experienced specific negative consequences of switching on a machine which contains failed capacitors, or a capacitor failing while it is running?
Quote from: "tomaz"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...
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.
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
Quote from: "t-rexky"Unfortunately this is not a joke :(
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:
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 :)...
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 ':shock:' 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
Quote from: "Rob Blessin Black Hole"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:
:shock:
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...
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.
I checked my monoturbo slab main logicboard and it seems to be pretty bad... electrolyte everywhere :?
@t-rexky: could you post your parts list please? would be very helpful!
thanks,
michael
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 (that's 3000 hour estimated life at 105°C. 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.
The through-hole capacitors that are used in the NeXT power supplies are of very high quality, all manufactured by United Chemi-Con. I refurbished three power supplies, all originating from different sources, and all of the capacitors that I removed had good in-spec capacitance and low ESR. They will however start failing at some point, but that may be quite a bit into the future if the equipment has been well maintained. Just to give you an idea, I have some HP bench equipment that was manufactured in the 70s and it is still working fine with the original electrolytic capacitors!
The surface mount capacitors from that era are a different can of fish though. They have been known to fail and take out expensive equipment with them. I believe it had something to do with the solder processes used at the time and the design of the capacitors leading to lack of overheat tolerance.
The biggest issue with old unused (stored) electrolytics is that they develop large leakage currents and may need to be reformed before resuming normal use. The excessive leakage current causes high currents in the circuit and may damage other components, such as diodes and transistors. Some old capacitor may also have compromised seals leading to dried-out electrolyte. Having said that, all the power supplies that I got from you have been working perfectly fine without any special capacitor reforming process :wink:.
Quote from: "gtnicol"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.
thank you t-rexky! I ordered a bunch of capacitors. for my trusty Macintosh LC 475 clocked @40MHz too :wink:
I am curious if you had any luck replacing the capacitors?
Quote from: "mikeboss"thank you t-rexky! I ordered a bunch of capacitors. for my trusty Macintosh LC 475 clocked @40MHz too :wink:
hello t-rexky
no, I didn't find the time to do it. also I now have a bunch of black hardware that runs just fine. but I ordered all the caps and I have them here, ready to replace the old ones. also I did find a really nice guide about how to remove the capacitors ->
http://450.servehttp.com/reference/caps/Edit by Admin: Internet archive to the rescue.
https://web.archive.org/web/20170103211408/http://www.classicmac.net/reference/caps/ (
https://web.archive.org/web/20170103211408/http://www.classicmac.net/reference/caps/)
regards,
michael
I set up my NeXT Color slab after a year in storage in my new house. It's pretty cool finally having enough room to enjoy all of my old toys. Unfortunately, I think the capicators might be going. The sound box makes static-noises during start up and I have had a couple of kernel panics lately.
I built a couple of Heathkit radios as a teenager, but haven't done much soldering since then. Any advice on how to proceed? Is it possible to identify all the parts based on their markings? I guess the best approach is to disassemble the slab and make a list of the parts I need. From the instructions, I think I could do the logic board. Not so sure about the power supply though.
Thanks,
Brian
(I am cross-posting this but some may not be following the Dimesion forum where I already supplied this information.)
I finally spent the final bits of time required to finish the slab recapping document. I loaded it into my DropBox account and it is available at:
https://www.dropbox.com/s/fiwxr8ejsx1loxw/NEXTSTATION%20Turbo%20Color%20Capacitor%20Replacement%20-%20NC.pdf I hope this is helpful to others who wish to refresh their units. Please let me know if you have any questions or comments.