Finally, a nice Quadra 840AV

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Elemenoh

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Oct 18, 2021
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Most Macs I come across in the 8x00 style case are trashed. Usually bezels missing, cracked plastics, yellowed etc. It was a treat to find this Quadra 840av in such nice condition. I'm afraid if I open it, it'll crumble to bits. I might just enjoy it like this for a while to avoid the heartbreak.

IMG_0333 2.jpeg
 

JDW

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I've never really understood what all the fuss is about when it comes to the Lisa (noting the one in the background above), mainly because it isn't such a practical machine. I do remember seeing one new on display in the computer store when my Dad and I went to pick up our brand new 128K machine in 1984. I pointed to the Lisa and asked, "what's that one?" My dad replied, "nothing we need." Of course, he was speaking of the heart-stopping price at the time, but even today, I've never really been drawn to the Lisa.

The Quadra 840AV on the other hand is the single most lustworthy vintage Mac on my wishlist, mainly because it's the fastest 68k Mac Apple made. Sure, you can accelerate other machines beyond it. But there's something magical about the 840AV in my eyes. And I must say, @Elemenoh, what a fine machine you have there! Thank you for sharing that lovely photo!
 

pfuentes69

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I've never really understood what all the fuss is about when it comes to the Lisa (noting the one in the background above), mainly because it isn't such a practical machine. I do remember seeing one new on display in the computer store when my Dad and I went to pick up our brand new 128K machine in 1984. I pointed to the Lisa and asked, "what's that one?" My dad replied, "nothing we need." Of course, he was speaking of the heart-stopping price at the time, but even today, I've never really been drawn to the Lisa.
Some failed machines like the Lisa tell an story that is worth of being preserved
 

Danny D

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Nov 2, 2021
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Nice find. I expect it will run early 90s 3D games (e.g. Hellcats: Missions at Leyte Gulf, Spectre Supreme) quite well, but I wouldn't power it on until all those nasty electrolytic caps have been replaced.

Macintosh_Quadra_840AV_logic_board_820-0382-10_%28661-1700%29.jpg
 

JDW

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Some failed machines like the Lisa tell an story that is worth of being preserved
Of course. Just not necessarily preserved by me. I shall leave that task of saving expensive Lisa’s to you fine gentlemen!

As for that beautiful Quadra 840AV though, I truly look forward to preserving one of those awesome Macs one day.
 

Elemenoh

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I bit the bullet and opened it up. Fortunately nothing broke. The battery was fine and the caps have leaked a bit but not terribly. I cleaned up the caps and surrounding areas with cotton buds and IPA for now since my 'lab' is being remodeled at the moment and I don't have easy access to tools. Unfortunately I get power, but no chime or video. So it'll probably need a recap and bath at least. Is this one of the models that requires a good PRAM battery installed to boot?
 

Patrick

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Oct 26, 2021
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I feel like the only computers that need good PRAM to boot is like the OG MAC II's and LC's.

but i could be wrong on that.

If its anything like the other Quadra's it does *NOT* need the pram battery.
 

Mac84

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I bit the bullet and opened it up. Fortunately nothing broke. The battery was fine and the caps have leaked a bit but not terribly. I cleaned up the caps and surrounding areas with cotton buds and IPA for now since my 'lab' is being remodeled at the moment and I don't have easy access to tools. Unfortunately I get power, but no chime or video. So it'll probably need a recap and bath at least. Is this one of the models that requires a good PRAM battery installed to boot?
Best of luck with the Quadra! Yours is in beautiful shape and it has the caddy CD-ROM bezel. ❤️

Sadly it sounds like you have the same issue mine is having, power LED turns on, PSU fan spins, and nothing else.

Does the CPU get hot? Mine does pretty quickly - but the rest of the board seems dead, even after multiple trace repairs and recaps. I'll be keeping an eye on this with great interest! 😄
 

Elemenoh

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Best of luck with the Quadra! Yours is in beautiful shape and it has the caddy CD-ROM bezel. ❤️

Sadly it sounds like you have the same issue mine is having, power LED turns on, PSU fan spins, and nothing else.

Does the CPU get hot? Mine does pretty quickly - but the rest of the board seems dead, even after multiple trace repairs and recaps. I'll be keeping an eye on this with great interest! 😄
Thanks! I didn't leave it on long enough to notice the PSU temp. Are you getting the right voltage out of your PSU? Did you try swapping in one from another model like an 8100?
 

Mac84

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Thanks! I didn't leave it on long enough to notice the PSU temp. Are you getting the right voltage out of your PSU? Did you try swapping in one from another model like an 8100?
Yes, I've tried swapping PSUs, CPUs, and RAM, etc.

The CPU and PSU are confirmed working in my Quadra 800. So that leaves me to believe the logic board is the culprit. :confused:
 

Elemenoh

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Yes, I've tried swapping PSUs, CPUs, and RAM, etc.

The CPU and PSU are confirmed working in my Quadra 800. So that leaves me to believe the logic board is the culprit. :confused:
Bummer. Did you check and/or swap the CUDA chip? IIRC from my brief cleanup, it's near one of the caps and looked a little crusty on mine. I've had similar symptoms on Color Classics that ended up being issues with crud under the CUDA, a dead chip or a problem with the nearby crystal.
 

Mac84

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Bummer. Did you check and/or swap the CUDA chip? IIRC from my brief cleanup, it's near one of the caps and looked a little crusty on mine. I've had similar symptoms on Color Classics that ended up being issues with crud under the CUDA, a dead chip or a problem with the nearby crystal.
Hmm, it does seem "okay" to me on the surface, but who knows. This thing has also been through the ultrasonic cleaner at least twice. But anything is worth trying!

By chance to you have a rough idea of what chips may be a suitable replacement?

Maybe some dedicated multimeter probing in this area would be a good idea.

IMG_1111.jpeg
 

Elemenoh

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Hmm, it does seem "okay" to me on the surface, but who knows. This thing has also been through the ultrasonic cleaner at least twice. But anything is worth trying!

By chance to you have a rough idea of what chips may be a suitable replacement?

Maybe some dedicated multimeter probing in this area would be a good idea.

View attachment 850
No I don't have much more info than that. And my experience on the Color Classic might not apply here.. was just a thought.

What is U12? I wonder if that might be involved too since it gets more exposed to C27 goo and is connected to the CUDA.
 

Kai Robinson

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Screenshot 2021-11-09 192207.jpg


Check the startup circuit in order: RED, YELLOW, ORANGE, BLUE, DARK GREEN, LUMINOUS GREEN have you got continuity and the correct resistances?

BTW U12 looks suspect to me. The full part number is 343S0120 - it's a 5v Regulator IC made by Sony. Available from Exshine and UTSource.
 

Mac84

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View attachment 854

Check the startup circuit in order: RED, YELLOW, ORANGE, BLUE, DARK GREEN, LUMINOUS GREEN have you got continuity and the correct resistances?

BTW U12 looks suspect to me. The full part number is 343S0120 - it's a 5v Regulator IC made by Sony. Available from Exshine and UTSource.
Thanks Kai!

I did touch up the pads (or even remove the chip) U12, along with whatever is to the left (in the photo) of C27, that's why there is some solder mask there. I'll try to map things out with the multimeter.

I've done so much work on this board over there years it's hard to remember what I did and didn't do. Of course if I discover anything that may help Elemenoh I'll be sure to share it.
 

Gayle

New Tinkerer
Nov 15, 2021
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I've never really understood what all the fuss is about when it comes to the Lisa (noting the one in the background above), mainly because it isn't such a practical machine. I do remember seeing one new on display in the computer store when my Dad and I went to pick up our brand new 128K machine in 1984. I pointed to the Lisa and asked, "what's that one?" My dad replied, "nothing we need." Of course, he was speaking of the heart-stopping price at the time, but even today, I've never really been drawn to the Lisa.

The Quadra 840AV on the other hand is the single most lustworthy vintage Mac on my wishlist, mainly because it's the fastest 68k Mac Apple made. Sure, you can accelerate other machines beyond it. But there's something magical about the 840AV in my eyes. And I must say, @Elemenoh, what a fine machine you have there! Thank you for sharing that lovely photo!
The Lisa was my very first exposure to personal computing. I was in college, and we had one Lisa to fight over at all hours. To me, it was an excellent word processor that I could use to type and then print out (no way!!) my papers. I honestly don't know what else it could do...forgive me.
 

JDW

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The Lisa was my very first exposure to personal computing. I was in college, and we had one Lisa to fight over at all hours. To me, it was an excellent word processor that I could use to type and then print out (no way!!) my papers. I honestly don't know what else it could do...forgive me.
Gayle, thanks for sharing that story. I was 13 in 1984. When my father and I were in a computer shop early that year to pick up our fist home computer (the Macintosh 128K), I recall spotting the larger Lisa on display near the Mac display. I asked, "What's that?" To which my father replied, "Nothing we need!" No doubt, he was unamused by the rather shocking price tag. The Mac was already quite expensive compared to other "home computers" on the market. All my school friends at the time (in California) had a C64.

I've never owned a Lisa so I cannot tell you all the benefits, but I do know that for a while Apple required all software developers to create their Mac apps on the Lisa since there was no development system on the Mac at the time, most likely due to the lack of RAM on the Mac.

Today, the Lisa remains popular among die hard collectors who are willing to pay a handsome sum for the pleasure of owning a larger Mac sibling, which in many cases cannot do as much as the Mac! That and the lack of space is why I've never personally sought to get one. To me, the oldest "fun-usable" Mac is the Mac 512K.