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  1. For the Analog board there is clearly a problem with the 12V (measured at 7V). But I don't really understand your suggestion regarding the MB. I have a good MB that works fine on a known good Analog board. So I suppose that this good Analog board provide the correct voltage to the working MB. Now using the MB that I want to fix on the good Analog board, the MB/Logic board keeps rebooting. Do you suggest to: Look at the voltage provided by the Logic board since it may be too high for this MB but fine for the other MB? Check the voltage on the bad MB and chang
  2. Hi Thank you for your reply, Yes, you are right, several traces are corroded. I did the patch wire while I was measuring with an ohmmeter connections linked by "corroded" traces. The Analog board need to be checked. I received the Zener doiod yesterday so I will see if I can save the Analog board. For the logic board, swapping the analog board with a known good one shows that the Logic board has still this reboot-in-a-loop behaviors. I can see a something quickly draw on the screen before it reboots. What is draw is something like an Sad Mac but it's not clearly drawn... a
  3. I did test the Logic board with known good RAM and I had garbage image and sound. Maybe I should swap the ROM with the working MB to check if the problems follows the ROM or the trace/shorts or bad components on the logic board.
  4. Hello, I have a Macintosh Plus that have 2 problem: The Analog board only provide 9.4V measured on the connector on the Analog board side (Same on the J8 from the Logic board). All the connector have been soldered (with new solder past). The board had bad corrosion traces but I did measured all connection with an ohmmeter and they all seems to be fine -> I will probably need to change the 12V 5W Zener diode to solve the first issue. (I guess). I know that the Analog board has an issue because I tested it with a known good logic board and I had the same issue (9.4V inste
  5. So I received the IC's for replacement... but before doing this task I wanted to do a second "vinegar" bath and warm water dipping therapy for the logic board. After this I did let the board dry and reseated all the IC's ROM and SIMMs (Except for the RAM, I decided to use another set of four). Finally I thought before doing any desoldering I will first record the Chime of Death for techknight so he could also provide valuable information about the speed of the chime (To me it sounded as a normal speed...). I was completely shocked to hear the "Bong"! Not the Chime
  6. Thank you very much Techknight for your extensive answer. I was wondering where would the "zebra" pattern where coming from... now I got the answer. VRAM default content. Yesterday I start looking at each and every trace on the board with a microscope just to see if corrosion where bellow the PCB coating layer. After more than 2 hours, the only thing I was able to "see" was the amount of oxidation on pads and IC legs! It's really horrifying when looking at them with such magnification. Then I started to check traces connection with my ohmmeter for the SW
  7. Thanks for the hints, I will have a look at reichelt.de. I also know conrad.de or the swiss version conrad.ch.
  8. Thank you. Yes you are right. I just finalized the order from DigiKey in order to repopulate the board with "fresh" IC. Also I took the chance to get spare bourn filter. If I'm lucky I will get the parts for Christmas
  9. Thank you Bolle for this quick reply! I will check the UE8 closely today (testing connections and re-soldering it). No I don't have an IC tester, but I do have a logic analyzer and a scope I guess I can try to spot signal patterns. I will check the UD8,UE8 and UF8 datasheet to try to figure out what I should expect. Are you suspecting this chip because it is closer to the C7 capacitor or because the 74LS166 are more sensitive than the other ICs around? Unfortunately it seems that the 74LS166 is hard to get from local supplier, I may have to order i
  10. Hi all, Several weeks ago I bought on eBay a Mac SE/30 Showing SimaSimac signs... I know it's not wise to buy an known not working system but I can't find one of these SE/30 easily where I leave (Switzerland). Working system that can be find on eBay are just too expensive. So I did roll the dice and hopped for the best... The exterior of the machine was in a bad condition, but luckily inside the battery did not exploded (This was my main concern). Sure the motherboard was full of dust, but beside being a bit dirty it was looking fine. Of course as you wo
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