Quadra 840av no video or chime

[Mike Richardson]

Quadra 840av no video or chime

- Installed fresh PRAM battery.

- Pulled all but one SIMM. Tried other SIMMs.

Any other ideas? Bad ROM, bad VRAM? I should at least get a chime even with bad VRAM I would think. PSU seems to be good, it's got two huge ass hard drives that spin up fine.

I don't have any other Quadra 840av machines to try the ROM from. At least I assume that's what the 64-pin SIMM is.

 

[Mike Richardson]

There are no NuBus cards.

The caps have leaked. I think it is fatal.

Replacement of caps will probably solve the problem.

 

[beachycove]

I have had this problem with two 840av machines. I'd do the usual: wash the board and give the machine another try as a diagnostic tactic, and replace the caps if it boots after washing.

 

[Unknown_K]

My second 840av has the same issues, turns on with no bong or video. Caps have been replaced but they had leaked over a long time and there is some crud around chips even after cleaning.

The ROM on an 840av is on the motherboard, the only 68 pin stuff should be VRAM installed 4 at a time.

I would try recapping that machine and see if it works, if you recycle it any chance I can have the back plate?

 

[beachycove]

The ROM on an 840av is on the motherboard

Actually, as I recall, one of my 840av logic boards has a rom simm, whereas the other doesn't.

 

[Byrd]

Sounds similar to mine; the issue was related to a faulty PSU with my 840AV. With the stock PSU it wouldn't chime, ended up switching it with that from an 8100 which looked much beefier and better quality.

It's still not 100% though, only chiming and booting first go, but it will not restart. Works fine but I have to leave it be for an hour or so before I can boot it reliably again

JB

 

[Mike Richardson]

Sounds similar to mine; the issue was related to a faulty PSU with my 840AV. With the stock PSU it wouldn't chime, ended up switching it with that from an 8100 which looked much beefier and better quality.
It's still not 100% though, only chiming and booting first go, but it will not restart. Works fine but I have to leave it be for an hour or so before I can boot it reliably again

JB

Interesting. Did your hard drives spin up on the stock PSU?

I'll have to check the voltages then. I do have a spare 8100 PSU from one that I dismantled.

 

[Unknown_K]

The drives spin up on my system, voltages check out on the 5v and 12v lines using a meter. I guess I can swap PS with an 800 to see if something else is damaged.