quadra 950 issues

[MacG4]

So i bought this quadra 950 a few years back and it was working fine untill recently. now sometimes it gong and power on fine, but no video. other times it will get the crashing mac tone. so i tried different ram,in different slots etc...still the same issue.also tried a fresh pram battery and zapping the pram. anyway got any ideas?

 

[Charlieman]

Clean out any dust and cruft around the reset switch. Check for leaking capacitors, but I think that this is the first time we've mentioned this type of failure for a Quadra board on this forum.

 

[MacG4]

alright will do. its a very strange problem. i figured the motherboard has gone south

 

[istar1018]

What about with all nubus / pds cards removed & scsi disconnected? Same thing?

 

[equill]

Is this happening with a NuBus video card inserted, or with on-board video, or regardless? Another slot for the video card? Brightness setting and video cable OK? Is the display in use the same one as hitherto? Is the DB-15 to VGA adapter configured correctly? These could explain the lack of video, but the error tones could argue that raster isn't even reached in the startup sequence. VRAM? If you disconnect FDD and HDD in turn, how then?

The car-crash failure sound implies that there is a PPC card in place, so there is another potential villain in the picture unless you meant the 68k Mac rising and falling death-arpeggio.

de

 

[MacG4]

no nubus cards installed. i will try some of these ideas

 

[wood_e]

I would try taking out the PRAM battery, and leaving the unit unplugged overnight.

I have rarely seen a vintage mac motherboard fail.

Also... do you have any weird SCSI voodo? Check the termination and maybe try a different SCSI cable.

 

[MacG4]

I would try taking out the PRAM battery, and leaving the unit unplugged overnight.
I have rarely seen a vintage mac motherboard fail.

Also... do you have any weird SCSI voodo? Check the termination and maybe try a different SCSI cable.

i have tried taking out the pram battery for a few minutes but no overnight. i have not tried a different scsi cable but that might not be a bad idea

 

[equill]

If you had the Q950 working before with the same hard drive(s) as now, it is not likely that you are suffering the termination problem that the unwary can run into: that the 950 was originally intended for setup with the termination on the cable rather than on the physically last drive. Unless you had it set up so, that is, and then removed the terminator for another purpose. These days, of course, what is now 'normal' on-drive termination is quite possible instead of the cable-termination in the original 950.

Half an hour is quite long enough to reset the MLB (ie, leave it completely without power). One other wrinkle is the NuBus. It is even less fond of having cards plucked out or inserted while the board is powered than most other NuBus machines are. The 950, as a soft-power (active power management) machine is powered as long as it is attached to a live mains outlet.

de