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LC 475 won't startup after recap...why?
Posted by: MarNo84 on 2020-06-01 05:38:00 Hi friends, I just recently recapped a LC 475 logic board. Usually it's nothing fancy about - did it dozen of times. But this particular one won't talk to me, even afte a good recap. It just had bad caps, no battery leakage or so... If I turn on the machine, the fan will start and the hdd starts spinning. But no chime, no display 🙁 I did wasch/clean it twice. Any special vias I have to check for continuity or are there any knows culprits maybe? I mean.. I'm not much into LCs and stuff that aren't compacts or Lisa or Quadra 700/840 machines ;p I did try to repair that board for a collector friend... Any suggestions or ideas are very welcome 😀 Marcus
Posted by: bibilit on 2020-06-01 05:53:32 Can be the Egret chip Marcus, i have seen it goes bad a couple of times. U29 (near the connectors) Also, keep in mind a good battery is required to have video.
Posted by: Bolle on 2020-06-01 06:17:42 If you don’t have a battery in there turn it off and quickly turn on again. Usually it should chime though even with no good battery installed. As bibilit said remove the Egret, clean up the area and solder it back on. This has solved similar startup issues on several Colour Classics for me. On the CC there is a cap right next to the Egret that causes this trouble.
Posted by: MarNo84 on 2020-06-01 07:03:30 If you don’t have a battery in there turn it off and quickly turn on again. Usually it should chime though even with no good battery installed. As bibilit said remove the Egret, clean up the area and solder it back on. This has solved similar startup issues on several Colour Classics for me. On the CC there is a cap right next to the Egret that causes this trouble. Hmm that U29 looks quite clean and good to me ... damn, I'm not sure, if I can desolder this IC :/ will a ordinary heat gun work or kill the chip? ...and I already consider that board as maybe toast :/ ..I did one really bad mistake here: this board was pre "tried to repair" from the former owner - usually I don't do/accept repair request on already repair attempted boards :/ @Bolle - is there a chance, that you may want to take a look on that board? I probably will include my Micron Xceed Grayscale Macrocolor card for some checks/repairs too ;p (I got me another SE30 and maybe will keep that Grayscale kit as it is really a rarity - I already have a green, amber/yellow and well why not even cool Grayscale compact Mac SE30 in my collection 😉 ) - I don't want to f**k up this rare card and due to your own experience I trust your work 🙂 Marcus
Posted by: just.in.time on 2020-08-01 14:55:12 Were you able to solve this? If not yet resolved, try checking the voltages coming off the PSU. I’ve heard the LC/2/3/475 (and all their variations) can require recaps as well.
Posted by: MarNo84 on 2020-08-01 17:47:02 Were you able to solve this? If not yet resolved, try checking the voltages coming off the PSU. I’ve heard the LC/2/3/475 (and all their variations) can require recaps as well. Hi 🙂 yes the LC475 board is up and running again. My very thanks goes to @Bolle he helped me with that little bugger. The End result looks like this now and I'm very happy. There was a bad/broken (literally) resistor and a little wirework was needed due bad traces/contacts 😀 To be true, the matching PSU was also toast but after the clean/recap it is now working again too (this one was easy, compared to the logic board) Marcus
Posted by: just.in.time on 2020-08-02 08:11:17 Awesome, glad to see it's up and running again 🙂 Edited to add: And yes, @Bolle definitely knows his way around the electronics. That fix is impressive.
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