Quadra 700 - no video

[mattdy4]

Hi Folks, first time poster here.

Have a Quadra 700 that powers on, leds, PSU fan spinning, but no video and no chimey.

Have replaced the PRAM battery and attempted a reset but it doesn't seem to do anything (assuming I'm pressing the right key combo on this ADB k/b)

Any ideas or pointers on likely culprits?  Only vintage Mac experience was a SE/30 which I fixed by recapping so this is my first real challenge.  Board looks clean apart from a slight bit of the blue stuff probably caused by the Nubus video card that was in there before it got to me.  No battery explosions or Tant bangs either

 

[Trash80toHP_Mini]

Since no boot chimes, probably not related, but what kind of display are you using? If it's an LCD (or CRT for that matter) that's not from Apple or an Apple Video Mfr. that's not MultiSync capable, that's the first thing to check for. ISTR that the Q700 puts out anything compatible with VGA @60Hz. What VidCard came in the box?

Welcome aboard!

 

[mattdy4]

Since no boot chimes, probably not related, but what kind of display are you using? If it's an LCD (or CRT for that matter) that's not from Apple or an Apple Video Mfr. that's not MultiSync capable, that's the first thing to check for. ISTR that the Q700 puts out anything compatible with VGA @60Hz. What VidCard came in the box?

Welcome aboard!

Thanks!  Good to be here

I'm using an M1212 Apple monitor which kind of works on my LCII.  Kind of works in that I get a grey screen and sad Mac chime on the LC, so I'm assuming the monitor is working fine.  I don't have any alternatives to try out or an adapter

I don't know what video card was in there.  Only supposition really as the blanking cover is missing and there was a tiny bit of battery gunk on the slot connector so assume something had been there

Other than floppy, nothing else is connected to the board.   No HD is connected nor extra RAM or VRAM, just what is onboard

 

[jessenator]

Welcome! 

Looks like you've covered the main would-be culprits! 

Like you mentioned, you've got RAM and VRAM soldered to the logic board, so you would be able to get a video signal of some sort on that Apple monitor, all other aspects of the Mac operating correctly of course. A previous card being/driving the main display shouldn't be interfering at all with that, especially with a new PRAM battery.

The no-sound is interesting. Have you tested the Q700's speaker? Even though the impedance is different, you could probably test it on your death-chiming LCII, and vice versa. Might be nothing wrong with it, and it's not a big deal really, but due diligence and all that... Also, check the traces if any of the sound components are connected near this:

bit of the blue stuff probably caused by the Nubus video card that was in there before it got to me.

Like copper corrosion blue stuff?

Another thing to try would be to see, if you have the tools, to get voltages from the PSU rails and make sure everything's getting to the logic board okay. I re-capped mine, even though it was working. A few of the caps were bulgy, but after nigh 30 years, new caps are a must in PSUs, really. Check out this guide for the compact desktop PSU types and cap lists. We have a few up there, not all, yet!  Taking them apart can be trickier than a normie ATX supply, but they're not terrible.

 

[mattdy4]

Just be way of update I tried an AD-205 VGA adaptor in case it was the monitor.  There was some corrosion on some of the chips near the socket end of the board so cleaned this up with a toothbrush + IPA but still nothing

Board appears to be getting power through to the parts I checked with a meter.  Generally +5.1v and +12v flat which appears fine given no load

 

[JRL]

Following - I have a Q700 with this exact same issue

 

[mattdy4]

Following - I have a Q700 with this exact same issue

Most of the chips are warm.  Not sure what the first stage in the POST process is but have you tried using a ROM SIMM (eg ROMinator or one from an SE/30) to see if it's a built-in ROM problem?  Unfortunately I don't have one to hand and ROMinators are out of stock for the time being