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Found 4 results

  1. Hi I'm looking for help please with my Quadra 840AV that I've owned since approx 1996. I used this superb computer for my audio editing business, after upgrading from a IICi, for several years until I eventually acquired a 7100. I removed the Digidesign audio cards and used it as an office machine after that before eventually moving it to the loft for storage. A couple of years ago I got it out to see what condition it was in then. I set it up and powered it on to find that there was no chime but it did power on and the drives spun. There was no video output. So I took it apart and examined the board. There were signs of capacitor leakage so I decided to recap it along with 2 of the 3 IIci that I still have. Having done the recap and added a new battery, I powered it on and to my delight it chimed and booted up fine. So I did a few checks and eventually put it away satisfied that I could come back to it at a later date and see what I might do with it. About six monthe ago I took it out again. It powered up fine again so during my tests with it, I put in an unidentified Nubus network card that had come in one of the IIcis. There was already a Village Tronic Nubus video card in the Quadra as well. I left it powered up while I did something else and about half an hour later I went back to it to find that there was no video output and it had frozen. Subsequent booting resulted in a blank screen, no chime although the disks spun up. Basically it was in the same state as before the recap. So I took it apart again, checked everything, removed the battery nubus cards and reset the board and tried again. I eventually managed to get it to boot but only for about 3 or 4 minutes before it froze again. Since then I have had it in pieces many times, cleaned it, resoldered the caps to make sure everything was fine there and examined the board thoroughly. Some of the traces do look a little suspect so maybe that has something to do with it's behaviour. I've tried removing the ram and replacing one by one. I unplugged the scsi and floppy cables and left the board with as little as possible attached to it. I bought a replacement power supply and tried that. The result is always the same. To get it to boot properly (but only for about 3 minutes) I have to remove the battery and leave it disassembled for a few hours then reassemble and power on. It will then usually chime and boot up fine before the screen goes blank and I have to start again. Occasionally, if I haven't given it enough time to "recover", I'll get half a chime before it shuts off again. It's as if something overheats and cuts out. One part that I haven't replaced (apart from the main board itself) is the Rom. Mine is the model with removable Rom on a board that sits next to the Ram. I'm not sure if I want to spend any more on this even if I can find a replacement Rom card. I'm normally pretty good with Apple products and I've been using them (and repairing them) since the early 1990s but this one has me completely baffled. The fact that it will boot fine if only for a few minutes makes me feel that I'm not too far away from sorting it. I'm pretty much out of ideas now apart from putting in a replacement board but they're pretty hard to find, especially over here (UK). So please, if anyone has any ideas where my problem might lie, I'd be extremely grateful for any advice before it drives me completely insane! Thanks.
  2. MinerAl

    Q840AV B

    From the album: MinerAl machines.

    Quadra 840 AV. HDD wouldn't boot, but mouse comes on screen and eventually the flashing

    © MinerAl

  3. MinerAl

    Q840AV A

    From the album: MinerAl machines.

    Quadra 840 AV with 500MB HDD, 8MB RAM System 7.5 Dirty case

    © MinerAl

  4. I recently acquired a working, but neglected Quadra 840AV. It came with 3 hard drives installed, an original CD-ROM drive, and with a 64 MB of RAM. It clearly needed a total recap of a motherboard and a good cleanup, which I did. Then I tested the machine, and I found out that a CD-ROM drive wasn't detected, even that it was connected properly. I figured out that it must be the drive that failed. Then I cracked open the Sony CDU561-25 drive, and to my surprise, I found capacitors that have leaked and corroded the PCB. The damage was quite bad, but fixable. There was a group that leaked, and they were three 16V 47uF and two 16V 10uF silver electrolytic SMDs. On the left side of the PCB, there were four 6.3V 100uF that looked okay, but when I changed them, they were certainly on their way to fail (fishy smell). So when I replaced them all with tantalums, the CD-ROM drive now works flawlessly, and I know that they won't leak ever again. Also, I was impressed with the build quality of this particular drive, it is massive and it has a voice coil laser mechanism, which just screams high quality all around. So, next time your CD-ROM drive fails, check the caps inside the unit. Also, if you have a Sony CDU561-25 or similar, it will be the smart idea to change the caps just to be sure, even if they are not leaking. Sometimes the CD-ROM unit will cost alone more than a complete computer, so it is worth it.