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Scored a beat up Quadra 950

joshc

Well-known member
have you checked @BadGoldEagle 's current project?

Thanks for pointing it out. I have seen it but I have reservations about it. It's certainly one way of doing it (and it looks very tidy), but it's just as easy to wire up an ATX PSU without needing those boards. Also, I'd rather not have the mains voltage going into a hobby PCB (no disrespect meant here at all, I am just not familiar with the requirements necessary to design a PCB to ensure it can take mains voltage safely). IMO it's much safer to have the mains voltage going directly to the new PSU.
 

joshc

Well-known member
Taking photos as I go...

PSU diassembled in preparation for the replacement.

I'll need to get some rust remover gel to treat the PSU enclosure with.

Top board removed:

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Wires cut and bottom board removed - this will be partly re-used for the peripheral power sockets on that board but the rest will be cut away.

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With both boards removed, the enclosure could be worse but it does need some treatment.

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Quick dust off:

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I did end up noticing what could be the problem on the original board, a burn mark near Q9. I'm still confident an ATX conversion is the right way though - the old PSU looks like it had a really hard life.

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I know someone that likes to keep a little stock of Q900/950 parts so I might see if they are interested in that board as a spare to ensure nothing goes to waste.
 

joshc

Well-known member
New PSU has arrived, and it looks like it's going to fit pretty well...

I'll try a quick wire-up to see if I can get any signs of life from the logic board.

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LaPorta

Well-known member
As for the "missing" components in the PSU, the vast majority of those large supplies that I have seen have blank areas for either different revisions of the same PSU, or another PSU that uses a common design. The parts aren't supposed to be there most of the time.

Also, +1 to salvaging the components. There's always someone who can use something, you just need to know who they are!
 

joshc

Well-known member
Quick wire-up delayed until more screw terminals arrive, I didn't have enough... oops.
 

joshc

Well-known member
While I wait for things to arrive so I can complete the PSU, I thought I'd progress the rest of this project.

Time to clean things...

The RF paint on the case is marked from the battery damage.

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And a few spots at the top of the case
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Hit it with some washing up liquid first:
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Still ugly but not as bad, that's just stained plastic now.

The top grooves were super dirty

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Cleaning in progress
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Mmmm better.

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Side panel before

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Side panel in progress

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The back was very dirty too...
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And after...

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(still need to use some isopropyl alcohol to get rid of the black pen marks)

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Side door before
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Front panel before

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Front panel after

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No feets :(

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I also started to tackle the surface rust on the drive carriers and PSU enclosure...

Got some rust remover gel, so far it doesn't seem to be doing anything at all (left it for a few hours already). I'll leave it and see what happens.

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The label said to apply liberally so... Who you gonna call?

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I also decided to try out the original Quantum SCSI drive, which is a 1.2GB model.

Hooked it up to my Q700 and ... wow ... it works!

Looks like it was last used in 2003, it has Mac OS 8.0 installed and IE 5. Not a bad run for it really.

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That's it for now.
 

Unknown_K

Well-known member
The good think about the Q950 case is outside of the faceplate it is painted so its easy to repaint if you have to.
 

BadGoldEagle

Well-known member
Thanks for pointing it out. I have seen it but I have reservations about it. It's certainly one way of doing it (and it looks very tidy), but it's just as easy to wire up an ATX PSU without needing those boards. Also, I'd rather not have the mains voltage going into a hobby PCB (no disrespect meant here at all, I am just not familiar with the requirements necessary to design a PCB to ensure it can take mains voltage safely). IMO it's much safer to have the mains voltage going directly to the new PSU.
Re that mains PCB, although I tripple/quadruple insulted the traces that have mains power (and protected the underside with a polyurethane sheet), I just don't feel safe having DC voltages for the Softpower relay on the AC board. I think I'll ditch the power outlet in my next build (yes, spoiler alert, there will be a new improved version) and replace it with a power switch (something all Apple desktops/towers unfortunately lack and I really don't understand why).

The main thing that worries me is a problem you'll also run into: Once you put everything back together you'll notice that the DC ground is connected to the AC earth. How? Because Apple thought it was a great idea to make the inside of the case conductive. As soon as you screw that PSU in, its metal casing is connected to the logic board's IO-shield, which of course is connected to the board's DC ground. Unlike the SE there is no insulation.

For me that's a big no no: You cannot possibly know what failure modes your new PSU has, e.g. how it handles having mains voltage connected to DC GND for example, which is certainly a failure scenario if you don't have GFCI/RCD. For most* people in Europe (* in France it was optional till '97 IIRC, in other words YMMV) it shouldn't be a problem but you simply cannot rely on your home to prevent a house fire. Or expect people to check their installation (as pointed out in the Quadra's user manual by the way) before plugging the computer in.

Interested to know your thoughts on the subject. Maybe I'm overthinking it.

Also:
- Do you plan on leaving the donor PSU's casing intact? The power inlet seems to be facing backwards and I don't think you can install the original fan back in if you leave it as is (its screws are rather long and may cause some shorts)
- How will you hook the mains input up?
- Your donor PSU is looking rather sleek and according to my own research, 25A is more than enough if you don't have that many hard drives.

Looking forward to the next updates. I'm happy I'm not the only one currently giving this mod a shot.
 

cheesestraws

Well-known member
Interested to know your thoughts on the subject. Maybe I'm overthinking it.

I don't usually use bold text, please forgive me here. Please read all the below with I AM NOT AN ELECTRICIAN I JUST WATCH THEM ON YOUTUBE before every word.

I think you might be. If the case somehow becomes live and it is earthed, there will be a short from live to earth, a large current will flow, the fuse in the PSU will pop or, failing that, the circuit breaker at the CU, and you have failed safely without shock risk. That's exactly what a safety earth is for. If the case of the PSU is not grounded, and mains starts flapping about inside and makes it live, it'll take out the logic board, and it won't be obvious why, so if you then open the case and poke it with the mains still plugged in, you'll get a shock. You are relying on the fuse in the PSU and the circuit breaker upstream, but either of those needs to work properly. So put a fuse in you have reasonable confidence in that's the right size.

You don't need an RCD to trip on that, though it will trip much faster; an RCD will trip at a smallish imbalance between line and neutral which is likely to happen if, say, someone is being shocked. This won't be a smallish flow of current.

Do not, do not, sever the AC earth from the case of the PSU, especially in our amateur circles where it is easy for wires to become unattached and go astray. It could actually kill someone.
 
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BadGoldEagle

Well-known member
Hi there,
Do not, do not, sever the AC earth from the case of the PSU, especially in our amateur circles where it is easy for wires to become unattached and go astray. It could actually kill someone.
The thought has never crossed my mind. But yes, this is Alternating Current 101.

I don't really know how the US electrical system works so I might be wrong. The plugs are polarized so the fuse should always be inline with the live wire (not always the case in Germany because the plugs aren't polarized). If a short from live to earth occurs, the fuse should provide sufficient protection (and the burst should be short enough to spare the LB). But if the fuse is on the neutral wire (again, 50% chance if the plug is not polarized), then it won't work as a safety device and the RCD should kick in. Even after watching dozens of electricians on YT and asking on EE boards, you can still find "experts" who contradict each other, hence the confusion.
 

cheesestraws

Well-known member
@BadGoldEagle Yup yup, I wasn't sure what you were getting at so I added that note just in case. Hope it didn't come across too lecture-y. Wasn't meaning to get at you, but on reading back my wording was a bit ambiguous. It's more just that I could see a reading of your post which suggested disconnecting the ground from the case of the PSU to prevent mains earth being connected to DC earth, so my post was more for later readers of this thread than anything else.

FWIW, in this specific case, both @joshc and I are in the UK so our plugs are all polarised (and have fuses in the plugs too).
 

joshc

Well-known member
The good think about the Q950 case is outside of the faceplate it is painted so its easy to repaint if you have to.
I didn't even realise this when I was cleaning it. That makes a lot of sense and explains why most of the case doesn't yellow, just the side door and front bezels. It's a damn good paint job because I scrubbed hard at it and none of it came off !

- Do you plan on leaving the donor PSU's casing intact? The power inlet seems to be facing backwards and I don't think you can install the original fan back in if you leave it as is (its screws are rather long and may cause some shorts)
Yep, the donor PSU is going to be used as-is without modification. Might have to face it the other way but I am pretty sure it's going to fit alright.

- How will you hook the mains input up?
After much procrastination, I bought a crimping tool and I'll be hooking the mains input up with an IEC lead chopped on the end with the cables crimped into insulated spade connectors and connected to the original Q950 IEC socket.

- Your donor PSU is looking rather sleek and according to my own research, 25A is more than enough if you don't have that many hard drives.
Yep, I think it's got enough juice - it's also less than 50% the size of the original PSU, so hopefully won't generate much heat.

Still waiting on screw terminals for a temporary PSU test. :cry:

In the meantime, I've carried on cleaning stuff...

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The metal chassis parts for the PSU and drive carriers had ugly surface corrosion. The rust remover gel didn't do a while lot in the end, so I've been sanding away whenever I get the chance...

Before:
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After (not perfect but a lot better IMO):

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BadGoldEagle

Well-known member
@cheesestraws all good m8 ;) but yes, building things so that they'll work everywhere in the world isn't that easy.

@joshc It looks definitely better, maybe you could give evaporust a go? I've only heard great things about the product, even from 68KMLAers.
I'm not sure painting is possible here (from an electrical point of view)
 

krishnadraws

Well-known member
I've used Apple Cider Vinegar to remove corrosion on a severely corroded Mac SE/30 metal chassis. It does a good job. I followed that up by spaying primer. It came out great! Good luck!
 

beachycove

Well-known member
I’d be content with it as is, personally, though possibly I’d rub it with some oil to inhibit further corrosion. However, if I were keen to restore the machine to look like new, I’d consider electroplating. It’s not hard to do — as I recall, a vinegar bath, salt, a small DC current, and a small piece of nickel or zinc would make it shine. I expect that YouTube has a gazillion how-tos on the subject.
 

joshc

Well-known member
Quick update.

I finally got the PSU hooked up. It powers on, the LED on the logic board comes on, a very faint pop from the speaker but no chime / no video. None of the chips are getting warm. Nothing has blown up.

5V on the PSU is being drawn down to 3.6V under load of the logic board - it seems to be OK without the logic board. I guess something is shorted on the board but not sure what.

After that test, I decided to wash the board so I'm waiting for it to dry out (not sure if it will fit in my oven, the board is huge...).

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joshc

Well-known member
Spent some more time on it today, reset/interrupt buttons replaced and traces to them repaired. Still no change in behaviour.

Replaced C34 and C35 next to the power connector as I thought their readings were a bit funny, but it didn't change anything.

Two voltage regulators and a chip close to the audio jack (U87 - 3440113-A) are getting warm, everything else is cold.
 

joshc

Well-known member
Stuff that's happened since my last post. To cut a long story short, I went down a rabbit hole with fault finding on that logicboard.

Managed to get a different logicboard. Same behaviour. OK what on earth is going on...

Turns out... I am an idiot and the PSU's 12V rail did not have enough load on it. I just needed to add a SCSI drive and all is well.

Just like the last logic board, this one is battery damaged so I need to remove all the RAM sockets, clean under them and fit new ones.

It gets as far as death chimes so I'm hoping it's as simple as this.

It's a work in progress...

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LaPorta

Well-known member
Josh, I can't speak highly enough of the product Evaporust. It just works incredibly well. Look it up, it is very easy to work with, and takes off almost everything.
 
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