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Breathing

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  1. Breathing

    Macintosh Plus reboot in a loop or vertical bars

    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 change the Capacitors on the MB... (I assumed capacitor on MB didn't have to be replaced) Else... Thank you for your help
  2. Breathing

    Macintosh Plus reboot in a loop or vertical bars

    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... and hard to tell since it only last for tens of seconds.
  3. Breathing

    Macintosh Plus reboot in a loop or vertical bars

    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 instead of the 12V) The logic board was cleaned and the ROM and RAM where re-seated. When testing the logic board with a known working Analog board, the Macintosh Plus will reboot rapidly in a loop. The screen is not even able to show a good icon, only try to show a partial image. To be safe I removed the Programmer and Logic switch to check it wasn't due to a reset being inserted by the bad contact on these switch. I check on the Dead Mac Scroll but I wasn't able to seen a similar issue. Power line on the logic board aren’t shorted... however on a good logic board I was able to measure ~150 ohm between +5V and GND, while on the "bad" logic board I only had ~70ohm Anybody had an idea on how I should proceed? I do have a working unit to compare and test parts... Thanks in advance
  5. Breathing

    Death chime and Simasimac on Mac SE/30

    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 of death! The SE/30 was alive! To conclude the main issue was between the screen and the chair I was so focused on the capacitors that where leaking all over the place that I didn't swap the RAM as a basic test... I never realized that the RAM would be the cuprite on the Horizontal line symptom. Here are the picture of the RAM (We can see "cracks" on the green protective layer on their PCB): Honestly I’m happy that it was that simple to fix it.. but I’m also a bit disappointed, I was expecting to have more challenge on this little SE/30.. well, the Hard drive is dead and the Floppy drive refuse to read my floppies so the restauration is far from complete but still. Next steps will be to have a look at the analogue board and see if some capacitors needs to be replaced (Maybe the hard drive is fine but the +/-12V line is dead?), cleaning the Floppy drive and find a HDD replacement. Thank you for your help and advice ! I have many more Macintosh to restore so it’s nice to see that the community is so active!
  6. Breathing

    Death chime and Simasimac on Mac SE/30

    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 SWIM part, but this is a tedious work and I will need days to complete the complete board. I was thinking of hooking a logic analyzer to the VRAM module and check the signals integrity (including data lines).. this might help to speedup the trouble shooting time. Then I will trace back to the nearest IC if the signals are fine at this point. Techknight, I will record the sound when booting, I will need to re-.-assemble the unit first. Also since I saw so much corrosion I will attempts another cleaning with long immersion of the board in hot water (I was only brushing on the surface and never submerge the board completely for a period of time (30 minutes should be fine to go beneath the ICs)) Having a document that describe the boot sequence of this machine would be very handy for trouble shooting. Experience that I’m lacking to make educated guess regarding issues on such old system.
  7. Breathing

    Death chime and Simasimac on Mac SE/30

    Thanks for the hints, I will have a look at reichelt.de. I also know conrad.de or the swiss version conrad.ch.
  8. Breathing

    Death chime and Simasimac on Mac SE/30

    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. Breathing

    Death chime and Simasimac on Mac SE/30

    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 it from China and be very patient... as well as very optimistic regarding the reliability of the chips solder on those web sites. Do you think that swapping the CPU is unnecessary? (--> Chime of death means there is audio and thus CPU activity?)
  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 would expect all the capacitor did leaked, so I first cleaned the board Removed all the electrolytic capacitor Clean the motherboard again. Finally I replaced the original capacitor with tantalum one (Expect for the axial capacitor and C6 since I couldn’t find tantalum capacitor that can be de-rated and would still fit the original footprint). I tested the connection from the new capacitor to make sure they made good contact and none did a shortcut on other traces. The ROM-SIMM the video ROM the CPU and all socketed IC where reseated 4 RAM Module where added A new Lithium battery for the PRAM has been put in place Bourns Filters where tested OK (Without the capacitors) (With the new capacitors) Unfortunately the Mac did boot with the Chime of Death (normal speed not slow) and the SimaSimac pattern. There could still be several issue that need to be checked but since I don’t own a second SE/30 I won’t be able to swap the ROM Video or the PAL IC. Since I do own a Macintosh SE a Macintosh IIx and IIfx. I would probably be able to do the following: Test the Analogue board/Power supply by usiung the one from the SE (But I seriously doubt this could be the problem) Swap the 68030 CPU from the IIfx with this Mac SE/30 Check each connection from the ROM Simm to the CPU, same for the RAM and the Mux. Use the ROM SIMM from the IIfx on the Mac SE/30... is this possible? In the mean time I have several question for you guys: On the board I can see that the Audio IC from Sony have corroded legs, but since I do hear the chime of death could I consider the audio part to be fine? I read that to clear the SimaSimac issue one could “pull” the audio IC by adding a 1k resistor between pin 7 and 15… but since my audio works is this still relevant? How one would trouble shoot the VRAM? Clearly I did not yet gone thru all trouble shooting step, but I hope I won’t have to replace SMD IC or VRAM since I don’t know where to source them thus this post to get other point of view and ideas to help me trouble shoot this. Many thaks for you help!
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