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andy2k68kMLA

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  1. Hello all, Has anyone ever tried to adapt a standard ATX power supply to an older power Macintosh? The power supply failed on my 7300/200 (I hope it didn't take the whole computer with it). I noticed that the ATX power connector fits the main power feed (on7300) perfectly and plugs in even. Has anyone ever tried this with success. I wouldn't mind buying a power supply for it but would like to know if it still works. (FYI the power supply died with a loud electrical snap. Looks like dust caused an arc-over on a TO-220 IC. If the computer still works, I might try replacing that IC if cheap and feasible.
  2. andy2k68kMLA

    Macintosh Plus Logic board problem

    Okay thanks for the info. I tried with two matching sticks installed too same result as having all 4 installed
  3. andy2k68kMLA

    Macintosh Plus Logic board problem

    Hello everyone I'm trying to troubleshoot a 1MB logic board (820-0174-C). It doesn't chime only does what I posted in the video. I tried reseating ram, booting only with 1 stick of RAM, etc. reseating and cleaning hi and lo ROM DIPS. Voltages are good from a good, working analog board. The -5 voltage regulator on the logic board measures okay (-4.999 volts). I hear the TSM DIP can go bad too. Any other ideas as to what might be wrong? Any other guides for troubleshooting the logic board. Please watch attached video. Thanks everyone. trim.524A3B4F-052B-44CA-9011-5E24ED3DEFEC.MOV
  4. andy2k68kMLA

    Macintosh Plus RAM compatibility

    Thanks for your response. I read too that Apple advises against composite SIMMS? Is that correct, how would you know if it is?
  5. andy2k68kMLA

    Macintosh Plus RAM compatibility

    Sorry if this is a duplicate post. I really did try to search the forum before posting. I have a 1mb Macintosh Plus and I would like to upgrade it to 4mb of RAM. It says 150 ns or faster 30 pin simm. I've seen memory for a SE 2 plus, listed as, 4x 1MB 30-Pin 80ns FPM Memory SIMMs on fleabay. Would those work? Anyone have 4 X 1mb SIMMs they would be willing to sell and ship to US:WI? Thanks everyone
  6. andy2k68kMLA

    Macintosh repair adventure

    Thanks TK I was thinking the same exact thing. I'll try to upload a video of what it's doing when I get off of work. Do you (or anyone else) know of a document that explains the logic board circuits. Something similar to the well written manuals made by Lee and Pina?
  7. andy2k68kMLA

    Macintosh repair adventure

    Thanks TechKnight. Do you have any other ideas / suggestions for troubleshooting the logic board? I have access to a nice oscilloscope? I've tried removing all memory expect one slot. Removed and cleaned all socketed IC's. Any other ideas?
  8. andy2k68kMLA

    Macintosh repair adventure

    Thanks so much for checking that for me, seems odd but normal. Any other ideas as to what might be wrong with the logic board. I've heard the TSM chip and -5 volt regulator fail on the logic boards. The -5 regulator seems good. Anyway to test the TSM DIP IC? Any other logic board testing procedures/documents anyone know of that I could try?
  9. andy2k68kMLA

    Macintosh repair adventure

    Hey guys, I had a break through (I think/hope). I bought another analog board but it had the same exact problem when I swapped it out with a different good AB. Tightly spaced horizontal lines and everything. So I started looking at the logic board. I measured all the caps and found C6 a 33 uf wasn't measuring right on my meter. Upon further scrutiny, I found that the 5 volt line measures 280 ohms to ground. This doesn't seem right, especially because the -12 and 12 volt lines measure in the 300K+ I'm going to check the -5 volt regulator first the the TSM chip per Pina instructions. Any other known logic board failures? Would someone mind measuring their analog board 5v line to ground? (not attached to AB) thanks guys for your help. Macintosh Plus logic board 820-0174-C
  10. andy2k68kMLA

    Macintosh repair adventure

    Okay I can give that a try. How do you know when U3 the optocoupler is bad? I've heard it can cause the flubbing. I will try posting a video of it to make sure we're on the same page. Thanks for your help! Any other tests or voltage measurements etc that I can do on J1? Will flubbing usually stop when you disconnect the logic board from the AB? Mine does.
  11. andy2k68kMLA

    Macintosh repair adventure

    Oh and replaced Q8 SCR crowbar TO220. Also, I've measured just about every diode, resistor, capacitor, inductor on the AB. None of the diodes are shorted or resistors open. All the new caps (and old) seem to be okay and measure high resistance. Q8 never gets hot indicating something is truly in an overvoltaged state. I forgot to mention I had also recapped the logic board.
  12. andy2k68kMLA

    Macintosh repair adventure

    Ever heard the phrase no good deed ever goes unpunished? Anyways, I own a not so long ago working Macintosh Plus 1 MB. I had recapped it with all new electrolytics. After I recapped it. I powered it up, it chimed and seemed like it was working, then about 8 seconds in started flupping (I'm assuming it's what it is, sounds similar to an analog telephone that's been off the hook too long, only sped up). I also removed solder, cleaned with alcohol, fluxed and soldered nice new shiny connections for flyback transformer, J1, J2 and J3. Did some voltage checks, the 12 volt line was low at 11.88 volts when I adjusted voltage for 5 volts. The 12 volt zener measured low voltage. I've since replaced CR18 - CR21, with upgraded parts (Schottky TO220). Now the voltage looks good on both 5 and 12 volt lines that stay in spec but it still is flupping. Display shows full screen of solid black and white horizontal stripes. Relatively fine lines. -5v regulator on logic board at -4.99v and looks good. If I unplug logic board flupping stops and just clicks and no display.
  13. andy2k68kMLA

    USB peripheral support in Classic OS

    Awesome! I actually received the answer I wanted to hear for a change (instead of being disappointed). Thank you guys for your help!
  14. andy2k68kMLA

    USB peripheral support in Classic OS

    I looked on the internets but couldn't find a conclusive answer. Are USB keyboards or mice supported under Mac OS 9 or earlier? I want to buy a G3 tower for cheap to run Mac OS 8 or 9. The G3 has native USB 1.1 drives. So I guess my question is will any version of classic Mac OS (9.1 or earlier) have native USB support. I'm waiting on an ADB keyboard from eBay but USB support would, obviously, work better. Thanks!
  15. andy2k68kMLA

    Macintosh 128k issues

    Cool Well I guess that seals the deal. You can get one new for about $235. Clearly it works well.
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