On Apr 8, 2013, at 11:35 AM, Jens Stig Olsen wrote: > Hi everyone > I am trying to revive my old machintosh plus computer which died years ago > (making some black smoke). I opened it and saw that their are 2 motherboards > into it one seams to be for the power control. On the mother board for the > power there is a component which burned. I ordered a new motherboard on > internet and changed it. But as soon as i turn on the power the fuse burn. > Anyone can advise on what can be happening, I am a bit afraid something in > the screen has burned and is causing the problem. I really want to fix it so > I will really appreciate your advices.
There is the logic board and the video / power supply board, the latter being the one with burns. Assuming the replacement video/ps boards are good it means either the logic board or some of the picture tube (CRT) hardware is faulty. AFAIK all the power supplies to the logic board are protected so if there was a fault on the LB it would be unlikely to burnout something on the video/ps board. So that leaves the CRT hardware, most likely the yoke coils. If one of these (there are two) overheats enough it can cause a short in the coil. Can you identify the failed (burned) component? On the board, some components are identified on the silkscreen, typically by a type code (one or more letters) and a number, ie. R1, L16, Q4, etc. The fact that the fuse blows as opposed to the other component burning indicates it MAY be a different problem, likely a problem on the replacement video/ps board. This sort of problem is hard to diagnose, especially remotely, in part because the most direct way of testing involves burning out boards. Documentation on the Plus (and most other computers) is skimpy at best. Most information that is available is user generated and deals with common problems. This problem doesn't fit with any I can recall hearing of. Sorry, I can't come up with anything better. -- -- ----- You received this message because you are a member of the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To leave this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/ --- You received this message because you are subscribed to the Google Groups "Vintage Macs" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
