Jump to content

captaineos

6502
  • Content Count

    53
  • Joined

  • Last visited

2 Followers

About captaineos

  • Birthday 01/30/1989

Profile Information

  • Gender
    Male
  • Location
    Canberra, Australia

Recent Profile Visitors

396 profile views
  1. Subject: Power Macintosh 7300 stops working after tantalum recap Hi Everyone I decided to replace the electrolytic caps on my favourite Power Macintosh 7300 computer and unfortunately it hasn’t turned on since! I’m writing for help on what to check or do, as I exhausted all checks that I can think of. The problem is power supply fan spins up, power LED on but nothing else - no video output, no chime or sad Mac sounds etc. I did make a mistake that has never happened before but was due to the multi platform nature of this logic board - I added two extra capacitors and subsequently removed them after one power on. I was able to see my mistake when I did a ‘cap count’ for the top layer of the board, there should be 9 47uF 16v caps but I had 11. I removed all the top side 47uFs with tantalums, and the two unpopulated spots fit and looked like ones I had removed. Troubleshooting steps that made no change - Swap the existing Sonnet Crescendo card for a stock Apple CPU card from my PM7600. - Reset CUDA by pressing with button with computer both on and off - Disconnecting power and PRAM battery for 10 mins and powering on - Replacing PRAM battery - Triple checking continuity of one repair I had to made on the left side of the board. The capacitor pad lifted at C189 so I toned out where the positive lead went to and added a kynar patch. I later compared the continuity of my patch to the other working PM7600 I have and it matches - so I am confident it’s got to stay. I did reverse my patch just in case and no change - Remove and reseat all chips such as VRAM, RAM, Cache - Went down to one VRAM and one RAM chip, then back up to two. - Double check of C56 labelled values and measured capacitance. On my Atlas meter the original cap measured 56uf with 10.0ESR (high). The silk screen of the cap is 47uf at 4v, not the typical 16v. This is the first time I’ve come across a 47uF 4v so I replaced it with a 47uf 16v. - Check for shorted capacitors by putting black lead on ground then testing the positive and negative leads of all capacitors I installed - twice! No shorts to ground due to soldering… - Spraying a fine mist of isopropyl alcohol on chips to see if anything was heating up quickly. The P74BA DS8925Ms heated up the quickest but still were not hot to touch. Heat is a great tool in finding shorted chips but I couldn’t detect anything. - No parts went up in smoke or were cracked after I turned it on. - I inspected the possible ROM chip on the rear side of the board and it’s perfectly clean / good traces. - I know it’s appropriate to use a tantalum on the cache card becuase my PM7600 has one from factory. The 7300 in question was electrolytic from factory. Interesting find that I verified against a PM 7600: Two capacitors are installed reversed from the factory. Initially I thought I had made mistake as the continuity test showed the positive was going to ground the bottom side of the board C392 and top side of the board C103. The board silk screening shows the + symbol and my tantalums match the board AND the polarity of the original caps. I have no answer why Apple reversed the caps (meaning negative is where the + symbol is labelled). I have not reversed my caps, they match the originals and the PM7600 for comparison. Board condition: No rotted traces, no battery leak, inspected with magnifying lens and no corrosion found anywhere. Working before tantalums put in. Soldering: I am experienced and have done probably 50 Macintosh boards thus far and this is my first time having a working board stop after recap. Continuity checks to vias against my patch done. No excessive flux or low temp solder running under caps. Conclusion questions: Attached to this post or linked are photos from my past two days of getting nowhere! Could it have been the two extra caps I added at the beginning that killed the board? OR Could it be the very low ESR of the replacement caps that changing the boards boot up? Considering there is no reference for caps online, I have typed the values into my spreadsheet and made a screenshot so the formatting is retained. Jeremy
  2. captaineos

    My apple IIe card is defective! Why?

    Please note there is a critical typo in the first post. The capacitor values are 22uf 35v, NOT 25v. Thank you Jeremy from Australia.
  3. Hi Everyone I have picked my fourth Colour Classic today. The CRT needs replacing as I think the blue gun / colour has completely dropped out. I have previously converted an Apple //c monitor to LCD by using only the shell and adding in video controllers etc. The video controller accepts VGA input so I was wondering as the 9" screen will fit in the CC shell, can I solder in a VGA cable to the mainboard? I'm assuming along the gold connector there is RGBHV or RGB Csync?
  4. Hi everyone A recent project has been servicing my Apple 12" Macintosh RGB monitor M1296 made by Mitsubishi. I have two of them in mint condition, both known to have minimal use. I turn them on every 3 months or so and keep a diary simply 'Working great! 01/01/2018". Well I went to test one and found vertical fold over symptom and quickly turned it off. Top down inspection looked fine so I started to dismantle the main and neck boards. This requires desoldering ground cables, the design is not user friendly at all. The further I got to the bare boards the more shocked I became. My hands were becoming stained with a fake tan look and I could smell the oil. When the main board sits in the plastic cage, was a thick line of wet capacitor goo. The whole main board was sitting in a pool of electrolytic leakage. I had to wear gloves to desolder and wipe down my ESD mat which was stained from all the crap. My theory is the sheer level of 'wetness' to both boards caused it to fry itself. All quite confusing as you'd think being 'low miles' that they'd last longer. I would never turn a M1296 on again until I've washed the boards. BOTH monitors were equally as 'wet', just the one shown had worse corrosion. I spent at least an hour going over both sides with thick and thin cotton tips and alcohol to mop up the goo. Later in the project I put the main board in a sink and poured alcohol over the solder side. Again to my surprise , the alcohol turned brown and the sink was full of brown run off. So the board was that filthy that even manual cleaning wasn't enough - it needed a scrub and rinse. Element14 are stuffing me around with delivering my replacement caps so I am yet to actually re-cap it. For the first time online I can present a reference list of capacitors: Main board V uF Ordered C525 50 0.1 1 C401, C413, C502, C523 50 1 4 C507, C520 50 10 3 C915, C921 100 10 2 Unknown 160 10 1 C416 25 22 ? C105, C526 50 47 2 West of C417 160 82 1 C517 25 100 Yes C414, C5151 50 100 2 C519 25 220 1 C205 100 e 1 C908 450 220 1 C919 180 330 1 C148 6.3 2200 1 C920, C417 35 2200 2 Neck board V uF Qty C6B5, C6R5, C6G5, C207 160 1 4 C203 50 1 1 C2B4, C2G4, C2R4 50 2.2 3 C6B3 25 47 C6R3 25 47 C6G3 25 47 C2R2,C2R1,C2G1,C2B1,C2G2,C2B2 25 47 9 C206, (C517 from main board) 25 100 2
  5. captaineos

    50% conquest - Color Dark Castle

    Really? I thought I had it for OS X, it's in a time machine backup somewhere
  6. captaineos

    DB-19 Hot Juicy Awesomeness

    I was wondering how this situation would be managed. Glad you bit the bullet
  7. Hi! 68KMLA forum members never cease to amaze - thank you for the instruction, consideration and time in replying. I no longer have to worry what disk images will show up on the Floppy Emu as I can prepare them beforehand should they be a DC6 format. Looks like it's time to learn Basilisk as well. My aplogies for not replying sooner. I'll reply here with how I go as I've had more files that dont show up outside of the non-standard 'The Treehouse' software as found on Macintosh Garden.
  8. Hi everyone It seems my $230 device can't read standard DiskCopy 6 files. It simply ignores any disk images even with the file extension .img The ever fast in replying Steve from BMOW suggets compatibility is only raw (.dsk) and disk copy 4.2 (.img) files, and if I'd like to use DiskCopy 6 that they need to converted before use. How can I do this? I've hit a road block The Floppy Emu isn't a mass storage device so I cant open the .img files on say a Mac SE on SSW 7.1 and manually open each image file and save them as the old disk copy format. Please help!
  9. captaineos

    PowerBook 1400c and mSATA SSD

    I too am interested in this. The CF solution is great and I wonder if better performance would come of MSATA drives. Both my PB1400's have CF IDE solutions now
  10. captaineos

    Books

    Gill! I'm excited becuase I too love these technical books. Very hard to find in Australia now. We should compare titles
  11. captaineos

    M0403 Apple Universal Monitor Stand

    Thank you so very much for documenting your stand and detailing your observatios. It sure matches the portrait display beautifully.
  12. 3 Photos showing before and after and case should display below but can be found here: http://imgur.com/a/7NyGF The latest addition to my personal Macintosh collection is the Colour Classic. The only description the younger seller gave was it didn’t turn on. Not being one to gamble I was about to pull the pin on heading over to buy it, but a CC sure is tempting. It was in dusty condition with minimal case damage (a few light scratches), near platinum grey plastics. I could see the dust, but I could also see a LC PDS ethernet card was installed and it came with keyboard and mouse. Deal! Work was testing my excitement with a 5 hour shift in the middle of the day so I did that and came home to start working on cleaning off the dust and seeing why it didn’t boot. First observations as I was taking things apart were the plastics were tough, and gee Apple sure crammed in a lot of things into one small case. I’m so familiar with the black and white classics internally that it was surprising to see the extra components required for colour. The logic board was very dusty, and more dust covering the analogue board. Interestingly the fan was near new in dust level - again my suspicions the CC was stored poorly were becoming stronger. Anyway dust is great - it comes off. In the kitchen sink goes warm water, vinegar. On the board goes a thin spray of bench cleaner. Using an electric toothbrush and dedicated brush head, I went around all the capacitors and chips. As the board was non upgraded, there wasn’t any RAM to remove before hand. I also added in a few drops of eucalyptus oil to further remove the decade old dust. The board was rinsed well with warm water (at least 2 minutes) then taken outside to shake the drops out. The board then went into the oven at 50’C for 30 minutes, turned over at the 15 min mark. After it was dry I got out my torch to inspect everything - there was still some gunk around chips adjacent to capacitors. Using a dry toothbrush head, I detailed around them to further remove the presumably electrolytic leakage. Then back into the CC to power on. Remember this is a soft on computer, switch on at the rear then start up using the power key on your keyboard. CHIME! Enjoy the video everyone: https://youtu.be/WJkVAAL9JV8
  13. captaineos

    Novy Mac20 Accelerator Card

    Hey everyone thanks for the kind replies. Here is a video I made just for james https://www.youtube.com/watch?v=3rdXE2djWn4 https://www.youtube.com/watch?v=3rdXE2djWn4 How to safely fit in a Macintosh SE board with an accelerator card
  14. captaineos

    Novy Mac20 Accelerator Card

    Hi Everyone I've been meaning to post photos of this excellent 68020 accelerator card for the Macintosh SE line. A researcher of physical sciences used this machine as a daily driver, later retiring it for a Quadra 800. When I received the machine, it was running a very old version of the Novy extension which wasn't running correctly. A huge effort was made to track down the latest version of the Novy utility for better System 7 compatibility. I succeed and found the installation easy. The performance boost in general use is noticable, for example scrolling windows is smoother. The delay in providing photos was the board was too big for me to remove with the Novy fitted. I have since figured out the safe way to remove it. I believe this card is quite rare. From memory the Novy company must have been bought out by Daystar, as the latest INIT for the card features their logo. The old version didn't. http://imgur.com/a/8zllW
  15. captaineos

    Mac IIsi Recap Success

    Thanks for posting. If I had found the caps being too big, I probably would have been scared away! odly enough the Two IIsi machines I've owned had been the most badly treated by previous owners yet work fine.
×