Quadra 610 Restoration Project

[androda]

Hello everyone,

I have a Quadra 610 DOS Compatible which I'm hoping to restore.  This machine has been unused for years and was given to me by someone who just wanted the data from it (easy task, hard drive is fine).  The power supply is in good shape, so that's helpful.

Symptoms:

* No video signal

* No startup chime

* No sounds of hard drive access (as if the system was booting)

Steps I've taken to address the issue:

* Washed logic board

* Replaced capacitors

Now that I've given the board a more thorough once-over it looks like there are traces which were erased by the capacitor leakage.  The attached pictures are from the bottom of the board (leaked through vias).  The red lines show where I have tested for continuity.  Broken lines indicate lack of connection.  The more I look at this board, the more traces I think I find which have been eaten away.  I think I'll pull off my replacement caps and check all the traces there too.  Probably some damage.

Does anyone have a Q610 and would be willing to pull out the motherboard and get pictures of these areas?  It's no easy task - I had to use a magnifying glass to get the pics I attached.  If I find any more badly corroded areas, I'll post back with more questions and images.

My fear is that I'm going to have bodge wires all over the place once I'm done with this machine.  But as long as I manage to fix it, that's fine with me.  This may be an impossible project given my soldering ability (these vias are 0.3mm, pretty darn tiny).  But I'm up for a challenge here. 

 

[360alaska]

I have a 610 board I can pull out of a parts machine and give you pics, I’ll be able to do it on Tuesday.

Have you checked the voltages on the PS?

 

[androda]

@360alaska Thanks. Yes, the power supply voltages are basically perfect. I haven't taken it apart though. Do they tend to need new caps as well?

 

[360alaska]

Not in my experience, they are pretty rock solid but it’s still makes sense to check.

 

[androda]

Does anyone have or know where I could find a schematic for the quadra 610?

As I was poking around with a multimeter testing for continuity, one of the chips on the board near the CPU decided it wanted to be a bird and flew away. Never seen that before (didn't think I was pushing that hard). This chip is right next to a capacitor and its legs were bright blue/green even after scrubbing the board.  It was U46, 74HC132. One of the pads ripped off the board.

I fear that my project is over now that the leg ripped. I can only really know if it's being used by checking a schematic.

 

[cruff]

I'm thinking it looks like surface mount with the remains of the legs on the pad?  There isn't a real obvious via at pin 13, but if the output of the gate on pin 11 isn't being used, then you could tie pin 13 to pin 12 to keep that input from floating.

 

[360alaska]

Sometimes a pad is just a pad, it doesn't have to lead anywhere! No trace + No via = no connection to that pad.

By the way, I am home now, do you still need pics?

 

[androda]

@360alaska pictures would be very helpful. I pulled all the capacitors if the board and looked around some more and found a few more broken traces by the capacitor near the edge of the board by the ram 3 Simms.

Now I just hope that my soldering skills are up to the task of fixing these tiny tiny traces. I might end up resorting to conductive silver epoxy.

 

[360alaska]

 

[androda]

@360alaska thanks. Can you also get a picture of the first area, with c194 through c197? It's next to the power supply plug on the bottom of the board.

 

[androda]

I've repaired (bodged) all the traces I knew were broken, and made a little progress.

Instead of silence and no video when I push the power button, I get the usual startup tone followed by the eight tone chime of death (and still no video).

Edit: anyone have a good resource for figuring out which components failed on the logic board to cause the chimes of death? I've read that system ram/vram often causes this. I don't have any ram installed of either kind, so it seems likely the pre-installed stuff has gone bad.

At this point I'm starting to think that getting a good 610 board and maintaining it might be a better choice.

 

[androda]

This project is not dead!  I'm waiting for some things to come in the mail so I can do hot air desoldering and clean up some chips which have corrosion on their pins.  And I'll clean up the connections to U46 while I'm at it.

 

[Bolle]

I would put my bet on more bad traces instead of component failure. Did you only repair the ones that have been visually broken?

Death chimes is something at least. Not sure if schematics for the Q610 exist, but if they do exist get them and start tracing everything. Even if there are no schematics available you might want to check if the basics connect fine - CPU data/address lines to the memory controller and from memory controller to RAM, VRAM and CLUT/DAC.

Check the Quadra developer notes to get an idea how everything is connected and see if that reveals more broken traces. (pretty sure it will  have been through this over a dozen times)

http://mirror.informatimago.com/next/developer.apple.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-68K_Desktop/Mac_Centris_Quadra_800.pdf

 

[androda]

Thanks @Bolle.  I have a lot more wire tracing to do.

I did mostly check that visibly broken wires were actually broken. On my next sweep of the board I'm going to check more carefully. There are a lot of smeared traces from the capacitor stuff.

 

[androda]

I'm still looking for a picture of the bottom of the Q610 motherboard, right near the power supply cable pins.  C197, C196, C195, that sort of area.  The traces between C197 and C196 are all completely gone.  Looks like there's a wide trace and maybe some thinner ones.  @360alaska When you have time, could you upload a picture of that area?

 

[360alaska]

 

[androda]

Thanks.  Now I know that C197 and C196 are only connected to the vias on either side of them.  Time to do more trace-tracing - my vias there look eaten through.

On another kind of interesting note, if I completely remove U46 I still get sound and the chimes of death.  I'm wondering what that chip is for.  Still haven't found schematics for the 610, and still looking around from time to time.

 

[androda]

I recently re-capped a Quadra 610 for a friend, and his board is in way better shape than mine (no damaged traces that I can see).  I verified that all of my bodge wires are in the right places by tracing the circuits on that other board.  But his has the same issue as mine:  chimes of death, even after washing the board and replacing the capacitors.

This seems to be a common problem for Quadra 610s.  I've been doing a lot of research and have found basically the same theme:  Q610 is working fine for a long time, followed by sudden unexpected chimes of death.  I think this points to the death of some component from capacitor leakage, which washing the board and replacing the capacitors does not fix.

Given that the 610s do the startup chime and then the chimes of death, the system is certainly trying to boot.  Does this mean that the CPU is OK?  The built-in DRAM?  I haven't found any good information about debugging the chimes of death from a hardware level on the Q610.  Maybe I get to be the one which stumbles into the cause of death of so many of these old Macs by poking around and trying things.