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About jmellidg

  • Birthday 10/05/1963

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    Madrid, Spain
  1. jmellidg

    Mac LC III don't boot up from a non apple HD

    Hi thanks for your answer. After days of fight I realized that the problem was in the HD configuration. I changed two things, the scsi ID from 1 to 0, and a parameter to start the disk always or just when system call. I'm not an expert in scsi business but now works. Thank you very much
  2. Hi, I've recently repair a LC III macintosh. It had a 500 Mb Quantum Apple disk, but ir doesn't work. I change the disk with an IBM 1 GB. I tried to install several times system 7.5, and I did, but when I shut down the computer, the HD didn't boot up. I have to start up from a diskette and then with LIDO or something similar mount it and then, always that I restart (don't shutdown) the mac start up fine. I try to initialize the HD with LIDO and with tha patched version of the Apple HD util, but no success Please do you have any idea about what to do?? Thanks in advance
  3. Hi guys, I need your help My problem right now it's a "whup-whup" or "flup-flup" noise when the mac is turning on. I'm going to tell you the story I bought a macintosh 512k with a dove MaSnap (scsi and memory) expansion card. I'm an european 220 V user and the Mac Power Supply is 110 V. I use a transformer from 220 to 110 V (I don't remember but I think that has at least 50 W.) When I started the Mac the very first time, there's a kind of horizontal lines, so I went directly to resolder the J1 connector (I've fixed 4 or 5 macs with a similar problem) but there were no success. Try to reseat the ROM's and the MacSnap memory. No success I think about swap the logic board with a Plus and test it, buttt... When I switch on there were a creepy sound, the fuse blow out.When I thought about it, I think that I forgot to change the power supply cable and I plugged in the Mac in a 220 V source. Sooo, I replace the fuse with a 3 A one (I don't have a 2,5 A) and try to swith on with a 110 v right now. Disaster.. the analog board began to burn. The Q10 tiristor dissappear, and a lot of resistances were completely burned. I test the logic board without the Dove expansion in a working Plus and it works ok. Soooo... I replace the following components in the logic board: R60 1K, R44 100, R45 1k, R46 22 1W, R47 1.5,R48 100,R49 1.5, Q10, Q9, C39, U3, CR28 and CR29 and the four bridge diodes (components characteristics according to Pina's book) When I swith on again, more burned components... I replace again the following components: R60 1K, R44 100, R45 1k, R46 22 1W, R47 1.5,R48 100,R49 1.5, Q10 (the other components seems to be ok) and Q11 this time When I switch it on, I've heard the flup-flup noise as we start this post. I follow the Pina's recomendations for a flupping set.. - Check R56 and put it down - Change C3, C24, C25, C26, C29, C30 and C31 - Change rectifiers CR21, CR5 and CR1 - Change Q8 Nothing... Finally I resolder: - Flyback - Power connector on analog board - Video Connector - A lot of suspicious solders.. Nothing... I don't know How to fix it.. can you help me?? I have the chance to swap the analog board with a plus, but I want to know where the problem is.. Thank you very much for your help!!
  4. jmellidg

    Problem with the analog board in a Mac512ke

    Hi, thank you for your fast response, I test several times to power on the 512 changing the SIMMS in the macSnap, try to reinsert the ROM chips, I think that I startup the mac at least 4 or 5 times with no issue. My first problem was when I swap the logic boards. As soon as I get home attach some pictures
  5. Hi, I'm a vintage macs loving and I'm very proud of fix a lot of 8 different classic macs (reading the great books of Larry Pina!!!). I have skills in soldering and I'm learning about electronics by practice. Until now, I have a high degree of success!! until now. I'm the owner of a 512Ke that shows a lot of tiny vertical lines at startup. There's sound, no friendly bong, just something like "grrrrr" no matter. I try to fix it and I saw my first surprise. It has a macsnap 3 memory and scsi expansión cards. The scsi card was free inside the box, no attached to the roms socket.I atached the scsi card, and resolder the yoke conector J1. No success, same result. I'm think in a memory or ROM error, so I think that it would be a great idea to swap the logical board with the logic board of a mac Plus. I have a 220 V macPlus and my 512ke it's a 120 V, but I think that probably it works. I'm seeking in the internet and i didn't see nothing to not to do it. Well, I changed the logical motherboard and turn it on. The fuse blow up. I was worried because I don't know why..After check out the motherboard, and saw no damages (at least at first sight), I thoght that I must changed the power supply and connect the 220 cable, not the 120 one (I have it together..) so I replace the 2,5 A fuse with the one that I have 5 A, thinking that everything it would be ok... mistake... When I powered it on, a Little burn was in the neighborhood of the Q10. 4 or 5 resistor burned and the q10 literally annihilate .. jejeje It was a very, very dumb mistake, I know.. Anyway, I would like to question you about this things.. - Is there any problem trying to do what I've done, swapping the logical boards?? - If no, what do you think about the first fuse crash?? Changing the voltage sources?? other reason?? - What do you think about the second problem?? Caused by the first one?? the same reason of the first crash?? Now, I'm going to try to fix this little disaster, and I trying to think about the components that I need to change, in order not to continue breaking my little boy.. I think to change these components: R60 1k R44 100 R45 1K R46 22 1W R47 1.5 R48 100 R49 1.5 Q10 E0122 EO121 EO102 SD8335 CR400Y ECG5589 E0102YA NTE5400 SILICON CONTROLLED RECTIFIER Q9E 2N3906 o ECG159 o 2761604 o 2N4403 o 276-2023 (T-PNP, 1A,. 6W, TO92) C39 470 mfd 10V 85C U3 4N35 ECG3041 (IC, 6-p, optoisolator, 2500V) CR28?? CR29?? Do you think that I have to change another components?? The bridge diodes?? Thank you very much for your patience, and I would be very appreciatte your help By the way, when I'll fix the issue I'l need your help with the macsnap and the vertical bars!!! Thx, Jorge
  6. jmellidg

    Mac SE video problem and battery corrosion

    Today, when I returned home, the mac works fine, at least for a couple of minutes. I'm going to resolder J1, L2, C1, and the flyback... anything else?
  7. Hi Everybody I'm learning to fix old macs, and this time I work in a very well looking SE. The problema was a tinny brilliant unique vertical line in the middle of the screen. I thought that the problem was the conventional one, related with a bad solder or capacitor in the analog board. Anyway, I dismount the unit and were suprised about the good shape of everything. I completely dismount and when I get to the logic board I saw lot or corrosión around the battery , covering the chasis even. I think that the problem was in the battery, so I clean everything as I can and replace the battery socket and the battery itself. I hopefully assembly everything again and Voila! the Mac Works. Pretty happy with the results, I tried to test another analog board from other damaged SE and it Works properly. When I back the original analog board again, the first error return. I don't believe it.. I mount the second analog board again and the mac Works again. The problem was, that five minutes after I startup the computer, the vertical line goes again in the middle of the screen. I'm very confused, because I think that it's very weird to have two analog boards with the same error (but possible at all) and I'm thinking that the error can be in the logic board, common to al tests I don't know if an error in the logic board can cause a problem like the vertical tiny line in the middle of the screen.. What do you think?? a double error in the analog board?? a trouble with the analog?? Thanks in advance!!!