I checked the Flyback and whole Video assembly , it looks fine on inspection.. I pulled the whole unit apart and I now know its the Switching Power Supply.. 1980 by Astec components LTD. The board mesures 4 by 7inches and looks very clean, exception of the Cap that blew, The fuse is not blown either.. LIke I said I shut it down as soon as I saw smoke.. The Obvoius bad component is the Capacitor (Its cracked on has skicky stuff leaking out) The Value is 0,1uF@X , brand is Rita, GPC , 250V-MP On inspection this looks to be the only bad part.. It is next to, in fact touching against I think a diod or transistor , its black with 3 legs (Wires) on it (GI KBP-10 8210).. I am not a professional board level techniction, but I do have alot of experiance soldering and working with electronic components.. I have basic tools like: Soldering iron, Ohm meter.. I should be able to reoair this myself with (Like the song goes) "A Little help So What do you think? Should I just replace the Bad Cap and plug it in again? Do you think it blew because of another shorted part ? Like I said the unit was still working when I shut it down, it was smoking like crazy tho.. It looks like the standard voltages +12, -12, Com, +5 noted on the circuit board.. Can anyone help...??? Thanks for your help... Phil Clayton

Thank you Tony for your interest in my problem.. I will try to locate a replacment Cap tomorrow or over the weekend.. And I will just replace the defective Cap as you said.. I also agree with you that its probubly all thats wrong with the old machine... I truly love this computer, finding not only one, but two after looking for quite awhile was a thrill and I look forward to some play time with my two Osborne 01's .. I also want to thank a very nice lady from Germany named Gaby, that also echoed the same advise as you did on the repair.. Brings up somthing I never considered about old computers that have not been used for many years.. These two Osbornes were not powered up for over 13 years, they are in mint condition kept inside for all these years.. I did not know that the years of sleeping can effect Capacitors.. I am now concerned about the other one, it has an odor like something is hot also in it comming out.. I have only had the second unit on for no more than 10 mins sofar, hopeing to sort of break-in the old caps on it without blowing the power supply on it also.. Has anyone else had this problem with old computers befor..? Again Thank you .. Phil Clayton Tony Duell wrote:

On 3 Sep 98 at 18:35, Tony Duell wrote: Tony, I tend to be a board switcher now (shame) and I usually just replace the defective component. When I first started I was more investigative and would replace defective diodes etc. Dried out caps is common in older equipment and while i've occasionally replaced them as in old audio equipment, I've always tended to think that they would take out other parts of the circuits with them. Does the cap short or open when they dry out ? Thinking about it , it makes sense that they would not damage other components as long as they did not short or be able to charge. Is this why you get failed PSU.s commonly with an intact fuse ? I've had 3 or 4 IBM PSU failures recently and have avoided trying to repair them since I think that a failed power transister usually took a bunch of other stuff with it and I think my time is more valuable than trying to track it down. Are failed electrolytyics the most common source of failures. ? Another source is a fan disfunction with heat causing failure. What circuit component is most likely to die under those conditions ? Having an overview of this you could quickly check the most likely offender and desolder it to check it . Of course if you had the circuit diagrams you could figure out the RC, pi, etc. functions but I retain little of the theory I studied long ago. Whatever the lackings of the IBM service manuals, they , like the army give you step by step processes and leave little to initiative. You have referred before to this dummy load 6V 6W device. If my memory of Ohms law hasn't failed me completely this works out to a 1 amp limit. I also imagine this has to be on the power good line. Is there any reason you use this configuration ? I have some old 6V 6W bulbs . Would these work just as well ? I must admit that you and Jason P have inspired me to go back to basics. I should warn you I have an IBM PS1 SVGA monitor I just acquired that I will be asking for guidance on , and if the stuff thats been on the list lately isn't off topic a svga sure as fuck isn't. :^)) ciao Larry lwalker(a)interlog.com

On Fri, 4 Sep 1998, Tony Duell wrote: Question: how can a power supply make noise when it fails in the manner described above? Sam Alternate e-mail: dastar(a)siconic.com ------------------------------------------------------------------------------- Ever onward. September 26 & 27...Vintage Computer Festival 2.0 See http://www.siconic.com/vcf for details! [Last web site update: 08/25/98]