631 board testing out of case

[croissantking]

I’ve hooked up my Performa 631 board to an SE/30 PSU with the +5, +12 and GND wires hooked up. I’m just getting static out of the headphone jack. The 68040 and Valkyrie chips warm up.

Is this a legitimate way to test it?

 

[joshc]

SE/30 PSUs don't work without sufficient load on them if I remember correctly, so the board alone may not be enough. What are the voltages if you measure at the edge connector of the board?

These boards support soft power, have you got an ADB keyboard plugged in to test that too?

 

[croissantking]

SE/30 PSUs don't work without sufficient load on them if I remember correctly, so the board alone may not be enough. What are the voltages if you measure at the edge connector of the board?

4.7V on the 5V rail and 14V on the 12V rail.

I guess I better try an ATX PSU.

These boards support soft power, have you got an ADB keyboard plugged in to test that too?

Yep, I do, but using the power key doesn’t seem to do anything. It seems the board tries to start up when power is applied. I should probably stick a probe on the reset line, right?

The board is fairly badly corroded, so it could be just that it doesn’t work. I was curious to see if I could get it to chime.

 

[croissantking]

Hooked it up to an ATX supply with the correct voltages.

It does chime, I heard it faintly a few times. There’s something off with the audio output. I did recap that section of the board and also swapped out the sound output jack with a nicer looking one to no avail.

 

[joshc]

Its hard to tell from the photo, is there cap goo under the sound chip? I think these are DFAC II?

 

[croissantking]

Its hard to tell from the photo, is there cap goo under the sound chip? I think these are DFAC II?

Yes it’s DFAC II… here’s the relevant bit of the board, it’s probably fair to say there’s residual gap goo around there.



Looking at the Quadra 605 schematics I see that the DFAC II needs a -5V input, which I haven’t hooked up. Need to sort that.

 

[Daniël]

Yep, I do, but using the power key doesn’t seem to do anything. It seems the board tries to start up when power is applied. I should probably stick a probe on the reset line, right?

Soft power only works if you have the necessary voltages/signals wired up for it.
AFAIK, they're the same as other Macs of that era, using a +5V trickle to power the responsible microcontroller (CUDA if I had to guess) in standby, and pulling the /PFW signal high if the keyboard or system power switch is pressed.

An ATX PSU does the reverse, it turns on once the Power On signal (green wire) is pulled down.
Hence it being an easy "hack" to force an ATX PSU to turn on by just shorting that wire to ground.

This page describes a circuit to invert the signaling, making soft power work with an ATX supply.
And the edge connector page of the PM6500 schematics should show you were the necessary signals are.

All that said, you can always just wire the voltages to the board, and simply use the Power On to Ground hack to force the board to power up.
Soft power obviously won't work, but it still allows you to test the board (though you'd need to wire in video to actually be able to see if it does anything beyond the chime).

 

[LaPorta]

Ok, so I had the exact same thing happen to me when I redid a Quadra 630 board for my kids back when. Apparently, there is some need for the box at the front of the machine (that contains the light, volume buttons, and front headphone jack) to be both connected and grounded properly. Then the sound will work correctly (assuming this is your issue).

Sound loss on custom Performa 637

Thanks for the earlier IDE suggestions, I appreciate it. So, I got myself an LCD and hooked it up...it works! Now I am having another issue. Sound has worked no problem on this thing. Now for some reason, it refuses to output sound. Let me rephrase that: if I start the machine up from cold...

68kmla.org

 

[joshc]

Ah yeah, forgot about the separate sound box for these.

But also, that DFAC chip does look dirty - it wouldn't be too much effort to hot air remove it, clean underneath properly and solder it back on.

 

[croissantking]

Ah yeah, forgot about the separate sound box for these.

But also, that DFAC chip does look dirty - it wouldn't be too much effort to hot air remove it, clean underneath properly and solder it back on.

I’ve done this now, including the inductor pack LP2 which looked nasty.





I also did some work around the VR1 transistor, which converts the incoming -12V to -5V and soldered a lead to S1 ready to connect up to the ATX PSU. This is worst corner of the board, which has quite a few broken traces.



None of this has made any difference to the sound output, which is static noise. The chime is audible if I push on the headphone connector at just the right angle.

Ok, so I had the exact same thing happen to me when I redid a Quadra 630 board for my kids back when. Apparently, there is some need for the box at the front of the machine (that contains the light, volume buttons, and front headphone jack) to be both connected and grounded properly. Then the sound will work correctly

Given the above stuff I’ve tried, this seems likely to be the issue. I probably can’t go further without actually getting a Performa chassis to work with.

 

[croissantking]

I went back to this corner of the board and realised that the transistor wasn't even connected to the rest of the board due to damaged traces. So I did some further repair work and verified that the transistor is putting out the correct -5V (and that it's actually getting to DFAC II).



I have to have the headphone jack halfway out of the socket, but I'm getting clear audio now. It chimes, and I can invoke the chimes of death with the keyboard.

 

[croissantking]

you'd need to wire in video to actually be able to see if it does anything beyond the chime

I don't know why it took me all day to think of this, but I hooked up my zuluscsi drive (which very handily has a DB-25 port onboard in addition to the normal 50-pin header) to see if it would try to boot from a System 7.5 image. And it does! All the way to the desktop, and i can interact using the keyboard.

I'm impressed – the board probably only needs some cleanup/superficial trace repair to get it fully running again.