When I turn on my Quadra 840av, it turns on but nothing shows up on the screen and there is no "Bong" sound. What's the problem?

Could be a loose connection somewhere, could be a dead PRAM battery, could be a bad monitor, etc. You done anything to it recently? p

hehehee (no "bong" sound) :)~ Is there a sad mac on the screen? hmmm no start up sound? thats the instant response to hitting the power button. weird... Check all your connections, inside, outside, open up the case and remove then press back in all the connectors to everything into place make sure their seated. Check your MotherBoard for any signs of damage like a burn mark somewhere or a burned up component, same with looking at everything connected inside (cards and stuff) for damage. Disconnect your Monitor and try to start up your Mac listen to hear the start up sound, look at the Monitor connector for damaged pins and look at the connectors for damage at the monitor and at the Mac case too. Reseat your Memory, In fact Reseat everything in your Mac case, all cards pull em out and Reseat them again, this could also be a Memory problem. Check and Replace the PRAM battery if it seems to be worn out, It may be dead and you may of lost some settings This may sound weird but sniff around your system, if something burnt out itll leave a residual scent that can last a few days, sniff your monitors vents and inside your Macs case, if something burnt out at least youll know if its in your Macs Case or Monitor. If you dont get and sad Mac face at start up, then your problem isnt a drive access problem. Im thinking you may have a Memory problem, maybe just loose or maybe defective, that may cause your Mac to hang right at start up. But the PRAM battery being dead could too... Hope some of thses things give you some direction and help to get you started looking for the problem. Im running a Quadra 700 68040k Mac made in 1992, and its still going strong after 10 years, but as with anything, some minor tweaks need to be made here and there to keep everything running well. Another Quadra Owner :-)

start with the battery. replace it and try it out. It's the most likely, and least intrusive fix you can do. Cheap too.

You haven't been inside an 800-series Mac, have you, fieraci? :) "Least intrusive" doesn't exist. To replace the PRAM battery, you have to remove the entire mobo...of course, while you're in there, you might as well do other routine maintenance, since it isn't exactly easy to get in there... p

p, You make a good point. I remember rooting around inside my 8500, and cursing the marque at every turn. To be honest I would rather spend the coin on a new Mac than fight with the innards of the 800 (NuBus) series (or first gen pci series). The G4 is a gift from the gods as far as getting in and out of the box. (Thank you Steve J!).

Dear all, I read this e-mail about quadra 840, I have another problem with a quadra 800, when I try to start it a message appears: This disk does not work on this macintosh. Use a more recent installer to apdate the start disk (system 7.1 does not work on this computer, you need a more recent versio) please if you have an idea help me thanks in advance Debora