Q950 Won't Boot

[retrotech42]

I have a Q950 that won't boot up properly. When I power it up, there is a startup chime, but it is very distorted and hardly recognizable. The only video output is a distorted blue screen. I've tried two monitors, a Color Display and a generic Dell VGA with a DB-15 adapter. I've tried reseating the RAM and unplugging/plugging back in the hard drive/CD drive. Is this a sign of capacitor failure? Or has something else gone wrong with the logic board? Thank you for help in advance.

 

[Unknown_K]

Quadra 950's use tantalum capacitors so no leaks. There is built in VRAM and 4 VRAM sockets, make sure if there are VRAM SIMMs installed they are the correct type and speed. Use a known good video adapter. I keep old generic 640x480 (no settings) ones around just to check machines when I get them (works on all machines and all monitors). Are you using a Nubus video card or built in video?

Make sure the RAM is installed correctly (you need matched sets of 4 and they are split 2 in the top bank and 2 in the bottom).

http://computers.popcorn.cx/apple/macintosh/quadra950/quadra950-04.jpg<=== picture of the motherboard for reference.

 

[Aoresteen]

Check the CMOS/PRAM battery.  weak/bad batteries can cause boot issues.