Quadra 840AV no video or chime

[Alec]

Hi all,

My Quadra 840 AV which I recently acquired from the roadside, has no video output, chime, or hard drive.

There was a note attached to it that said it needed a new PRAM battery, so I replaced that.

Still no chime, most likely because of the missing HDD.

I remembered I had a 50 pin SCSI hard drive from a Classic II that wasn't working, so I tried using that to terminate the SCSI cable.

It would start up, seek the HDD, wait 20 seconds, seek again, and would continue in that fashion until I turned it off. Yet again, no chime.

I don't have the caddy for the CD ROM drive,so I have no way of booting with that, but I think the floppy drive works, though I'm not sure how to boot from that.

I'm pretty much at a loss here, I don't know what to try next, so that's why I thought I'd ask here.

Thanks,

-Alec

 

[aladds]

Reseat the RAM (and VRAM if it has any), pull any NuBus cards out, disconnect everything on SCSI and try again. This eliminates other things which could be interfering (SCSI bus conflicts etc.). Then re-add things if it works.

Maybe even try a PRAM zap when you turn it on (hold Command-Option-P-R as it boots)

 

[Alec]

Reseat the RAM (and VRAM if it has any), pull any NuBus cards out, disconnect everything on SCSI and try again. This eliminates other things which could be interfering (SCSI bus conflicts etc.). Then re-add things if it works.

Maybe even try a PRAM zap when you turn it on (hold Command-Option-P-R as it boots)

I forgot to mention that I reseated the RAM and VRAM both of which had four cards in the slots.

As for NuBus cards there are none.

So what you're saying is disconnect all the SCSI devices and try to boot without any plugged in?

Also, I've tried a PRAM zap and putting it in standard TV mode, since I don't have a 15 pin to VGA adapter.

One more thing, how do I boot from a floppy?

Thanks,

-Alec

 

[ArmorAlley]

Hi Alec,

You should get a chime at startup regardless of the absence of a hard disc. I don't have a Q840av, but I start with the bare minimum (as little RAM as possible, no cards, only fans plugged in) and progress up from there. You are going to need a DB15 to VGA adapter and a SCSI CD player. Actually, get a CD-burner (like a Yamaha 4416). They can be useful.

You need a bootable floppy. There are many on the Macintosh Garden. System 7.5 should work well. Do you have another old Mac wirh which you could make the boot floppy? If so, burn yourself a copy of the System 7.5 and Mac OS 8.1 CD images from the Macintosh Garden on your Internet mac. Then using the Apple program DiskCopy on your other mac (if one exists), make yourself a floppy of the Disk Tools disk.

Alternatively, I think that BigMessOWires has System floppies for sale on his website. I'm sure that someone on this forum would you make you some, if you asked nicely.

I'm not sure that I understood what you said about the internal SCSI. The bus must be terminated, but it is almost always done with a jumper on the internal device. Look for the phrases 'TPR' or 'Term'.

Lastly, be open to the possibility that something on your motherboard has died and that you may need to get the board recapped.

 

[Alec]

Hi Alec,

You should get a chime at startup regardless of the absence of a hard disc. I don't have a Q840av, but I start with the bare minimum (as little RAM as possible, no cards, only fans plugged in) and progress up from there. You are going to need a DB15 to VGA adapter and a SCSI CD player. Actually, get a CD-burner (like a Yamaha 4416). They can be useful.

You need a bootable floppy. There are many on the Macintosh Garden. System 7.5 should work well. Do you have another old Mac wirh which you could make the boot floppy? If so, burn yourself a copy of the System 7.5 and Mac OS 8.1 CD images from the Macintosh Garden on your Internet mac. Then using the Apple program DiskCopy on your other mac (if one exists), make yourself a floppy of the Disk Tools disk.

Alternatively, I think that BigMessOWires has System floppies for sale on his website. I'm sure that someone on this forum would you make you some, if you asked nicely.

I'm not sure that I understood what you said about the internal SCSI. The bus must be terminated, but it is almost always done with a jumper on the internal device. Look for the phrases 'TPR' or 'Term'.

Lastly, be open to the possibility that something on your motherboard has died and that you may need to get the board recapped.

I had read somewhere that unless the SCSI bus was terminated, it wouldn't chime, so I connected an old HDD because I didn't have a terminator. (do you need only one device to be terminated e.g the CD drive? I'm not familiar with SCSI.)

Also, why do I need a SCSI CD player/burner when there's already one in the computer? All I need to do is buy a caddy for it.

Will a Powerbook G4 with a USB floppy drive work for writing disk images?

Looks like winworldpc.com has a full system 7.5 install, with the Disk Tools image along with it.

Also, I'm capable of recapping the board myself, could the PSU have bad caps in it also?

Thanks,

-Alec

 

[ArmorAlley]

Hi Alec,

 I take it back. You are correct, you don't *need* another SCSI CD-ROM, but one that doesn't use caddies will be a lot less hassle and much faster. In my experience, CD.ROMs that use caddies are 1x or maybe 2x speed. As it is at moment, you have to buy a caddy. Whenever I have gone looking for them, sellers have wanted $10 per caddy. You can get a SCSI CD-ROM for that price.

 If there are devices connected to the SCSI bus, each physical SCSI bus must be terminated by the last device on the SCSI bus, irrespective of what SCSI number has been allocated to said device. Internal devices have jumpers for termination. External devices require either an active or passive terminator, or there will be button for that purpose.

If our PB G4 with USB floppy drive is perfect. With TenFourFox, you have the capability to download disk images direct to your PB. If you get yourself an AAUI-to-RJ45 adapter, you can make an ethernet connection between the Q840AV and PB G4.

The Q840av is over 20 years' old. It is very possible that the PSU needs recapping. There are others on the site who can give you more detailed info and let you know what to look out for.

 

[Alec]

Looks like SCSI CD ROMs are actually more expensive than a caddy on eBay right now, so I think I'll go with that instead, unless I can find one at a hackerspace I go to.

 
I also happened to get the AAUI-to-RJ45 adapter with it, so I can probably use that.
 
Is OS X 10.5.4 on the powerbook too new to write floppies?
By the way, I found a fascinating System 7.5 download on winworldpc that has a DOS/95/98 utility packaged with it that allows you to make mac formatted System 7.5 install disks.
 
Also, can I eventually use a 68/60 pin SCSI hard drive with an adapter as the main HDD?

 

[beachycove]

Capacitor failure?

 

[Alec]

Capacitor failure?

Yep, looks like it, there's liquid and corrosion by all the capacitors.

I just washed the board after removing all the RAM, VRAM, etc... and it looks like the liquid is gone, though there is noticeable corrosion on some traces, vias, and components.

I'll replace all of them once it's done drying, and check for continuity on the damaged traces.

 

[Unknown_K]

840av boards seems to die easily from leaks while others types are easy to fix.