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BGE's take on the Quadra 900/950 ATX PSU Mod

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25 minutes ago, BadGoldEagle said:

This is starting to look like a monologue but no worries :quadra:


I love monologues (and the effort of course)! And better yet, the day I get hold of Quadra 900/950 this will be gold! Keep it up!

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Thanks guys for your support! 


@cheesestraws I also have 220/230V where I live, but the 'worst case scenario' is with the US mains voltage. To get the same wattage, they need about twice the amperage, and more amperage means more heat and a bigger copper surface. For 230V operation, those requirements are basically halved. 


The AC tracks are 3mm wide. I calculated those using a PCB trace width calculator and got the following results (notice how voltage does not enter into the equation):


The Becker draws 6A @120V (or 3A @240V). Because I chose a safety factor of 1.5, the maximum target current is about 10A. I decided to use a PCB with 2oz of copper (which translates into 70um of thickness for one copper layer) to cut the width down in two. The problem is, I'm not sure those calculators can be trusted.


Back to the DC side...

I think I found a solution to my problem...

Because of the black cable tie thing, the extension cable can't fit as is into the casing (the solution would be to get rid of said tie and that would reduce the structural integrity of the connection even more). 

One connector has to be removed to guide the cables inside the plastic cable tie. And here's the thing: What's the point of installing a connector if you can't remove the cable afterwards without modifying it some more...


So I think the following solution is the most practical: (it's not perfect so if anybody wants to chime in with a better solution, I'm all ears)

1/ Get an ATX extension cable. They're really cheap and plentiful.

2/ Cut the female side.

3/ Guide the cables into the cable tie thing. 

4/ Solder the cables directly to the DC board. 


If further modification has to be done, the male connector of the extension cable can still be removed. 

This solution is effectively what Delta thought was best for the original PSU...

I was all in for originality, but all black wires (I think) will look hella more professional.


Now, for the PSU 'rejuvenation' kits, I'll probably sell some boards (I'll have 4 extra 'DAY-1' boards since I have to order a minimum of 5) with everything pre-soldered. You guys would only have to put the 24 pin male connector (Quadra LB side) back in properly. The gerber files will still be provided free of charge but my boards may end up cheaper (especially if you're in Europe). 

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4 minutes ago, BadGoldEagle said:

I also have 220/230V where I live, but the 'worst case scenario' is with the US mains voltage. To get the same wattage, they need about twice the amperage, and more amperage means more heat and a bigger copper surface. For 230V operation, those requirements are basically halved.  

That's true.  Sorry, obviously a brain failure here.  And I'm not sure where I got the idea that you were in a 120V region, given that it plainly says where you are on your profile thing.


I'm doing well at the whole 'paying attention' thing today, aren't I...

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Proposed DC board layout:







- As explained in my previous post, J1 "Quadra 9x0 Logic Board" is not a connector. The extension cable will be wired in permanently at this position.

- Added compatibility with 20 pin ATX PSUs. A 24 pin one is still preferred though. 

- Optional 3.3V and 12V dummy loads. 

- Added a SoftPower bypass for people who lost their keys or have a damaged motherboard (per @Compgeke's suggestion. Thanks again for sharing your first draft! It was really useful for a beginner like me.). External power switch required in any case to prevent arcing when connecting AC. People with original Quadra PSUs should also invest in one of these switch/cable assemblies anyway. 

- Ground plane on both sides but the screw holes on the top are not connected to earth this time. The other three holes are for the original standoffs. I may add another one...

- Couldn't find a smaller pot. This one will have to unless I find one of those low profile flat ones. BTW, you shouldn't mess with it when the power supply is on. ACHTUNG LEBENSGEFAHR!


And now, here's a nice picture showing how it'll look (NB DC board is an earlier revision, the AC board was changed a bit and the ATX PSU's casing will be removed of course...):




HD connectors are lining up really well!


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Okay, the latest boards (v0.4) are in!

This time they should be pretty much finished. 


DC Board: 



AC Board (not to scale, obviously):



As promised, the Gerbers (fabrication files) will be available free of any charge... and here they are:

Gerbers QuadrATX DC.zip

Gerbers QuadrATX AC.zip


They'll be checked one last time but I'm pretty confident they're more than fine!


I plan on using JLCPCB. Stylurgys (not a member here, but he dedicated a lot of his time to my questions re: electrical engineering, board design etc) recommended them to me. Apparently they're cheaper than PCBWay. The next step is to get a quote from reputable manufacturers. 


I calculated the track widths based on 2oz copper layers. Use 2oz especially if you live in a 120V country. I've over dimensioned everything (the smallest track width used for the entire project is 1mm, more than necessary.) so 1oz is probably fine too. Expect to see price comparisons in the next days.


Final Bill of Materials (BOM) is also to come.

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Back with some quotes. 2oz copper layers are way more expensive (20 bucks per card extra) than what I had in mind. Therefore, I'd had to recalculate every critical 'net' to accommodate for 1oz layers.



I've used this site to calculate the temperature rise.


I'll be using FR-4 laminate (standard), so the MOT (Maximum Operating Temperature) is 130-140°C. The worst case scenario is with the Hard drive (aka Molex) connectors. I know a HD won't draw 10 Amps per rail continuously but that's the spec according to Molex. Even with a 3mm 1oz deep track, we should keep well clear of the 130°C limit (67°C in this case). Voltage drop is minimal (0.01V apparently). 


Both boards were revised. I can't seem to be able to delete previous attachments though...

Here are the new ones:

Gerbers QuadrATX AC new.zip

Gerbers QuadrATX DC new.zip


And now, the most interesting part... the cost (for 2x5boards):

PCBWay (+RoHS compliant boards): 84€ (custom duties included??? no idea)

JLCPCB (+RoHS compliant boards): 45.28€ (with S/H and custom duties).


Unless someone suggests another PCB manufacturing house, I'll go with JLCPCB. 

I'll keep 2 of the 5 boards produced. That means I'll offer 6 bare boards (3 AC & 3 DC) for 5 USD each. Anybody interested?

Edited by BadGoldEagle
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I'm going to have to make yet another version. 


1/ I found some Molex spade connectors that have a slightly different footprint. I'll update the AC Board soon with the new dimensions. 


2/ The EMI filter is expensive (12 bucks). I'll investigate how much the raw components cost and perhaps make one myself. I don't think that deleting the filter is a good idea. 


3/ I FINALLY tracked down what the PC pin style connector on the original board was... It's a JST B1P-LV-TA. "Since the pitch between circuits is large, 8.0mm, this connector is ideally suited for the power supply circuits of TVs, stereo systems and VCRs." The "VCR" bit definitely dates it... It's not available anywhere but on alibaba: https://www.alibaba.com/product-detail/Original-New-JST-connector-spot-supply_60584095453.html?spm=a2700.galleryofferlist.0.0.75cb1e95wGhAtp

I've never bought anything on that site. Do you have any recommendations as to how to pay securely etc? 

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Sure thing @Renegade. I guess those will be for your 900 & 950? You want two sets (2xAC+2xDC) or only one set of the two (1xAC+1xDC)?


In other news, I've had to replace the relay. It now has a 12V coil. For one it was a bit on the expensive side and it was also out of stock at Digikey and Arrow. I could only find it on Mouser. 

I have decided (for now) to keep the EMI filter as is. Designing those things can be a little tricky and if I manage to make a poor one, while it may end up 5-6 bucks cheaper, I don't think it's worth it. That FN405 unit is a really high quality one. 


As ever, Arrow turned out to be the cheapest with a total of 33,79 USD for the parts. Mouser comes second at 43 USD, and Digikey third at 46,10 USD.


With S/H fees to Europe included, the price is:

- Arrow: $40,21 (about €37)

- Mouser: €59,25

- Digikey: $67,00 (custom duties NOT INCLUDED)


To US states:

- Arrow: $44,71

- Mouser: $51,61

- Digikey: $54,73


Again, Arrow won. The only issue is that I can't share my cart... Parts have to be added one by one if you plan on buying the parts through them. It only takes a couple of minutes so that's all right.

I'll upload an excel spreadsheet with links to parts and carts (for Digikey and Mouser) as soon as it's ready. 


Also, one last thing. Please let me know if like Renegade you'd be interested in getting some boards. If I order 10 of each, I'll be able to lower the price!

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2 hours ago, BadGoldEagle said:

Sure thing @Renegade. I guess those will be for your 900 & 950? You want two sets (2xAC+2xDC) or only one set of the two (1xAC+1xDC)?


Yes, you guessed right :-) . They're both dead at the moment...

I'd be willing to get two sets.

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Ok, I'll order 10 sets then!


4 are still available (6 of the 10 are on hold, 2x for cheesestraws, 2x for Renegade and 2x for me). I'll probably post something on r/vintageapple, maybe someone there will be interested too. 

Now I can offer sets at $8 a pop (instead of $10, shipping still not included). 


I have solved the "PC pin connector" sourcing issue. I'll just buy a lot of these on eBay...


... and cut them in half. There won't be any downsides as the original connector used by Delta didn't have any plastic insulation to start with. I'll pre-solder and include them for free on my bare boards. I don't know if I'll have enough time on my hands (I have to go back to work next month) to offer fully assembled boards. Maybe though...


Which only leaves two relatively small issues:

1/ I'd like to find pre-crimped wires for the relay's DC connector. KK396 is now slightly obsolete and I don't know if L1NK terminals are 100% compatible with those connectors. I need to contact Molex about this. If they're not, I'll probably replace the KK396 connector by something newer.

2/ I would also have liked to find pre-crimped wires with spade connectors to connect the AC board to the new PSU. I think I'll just have to get some bare 16AWG wire and crimp those myself. 


More to follow.

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Right, so awesome project, and I have two Q950s that will eventually need a power supply.


I don't really need one of these now, but I really have to say you should put this up on GitHub, with the KiCAD file, Gerbers, all the BOM, and maybe a few pictures and assembly instructions. Also link to the GitHub project in this thread. With that, anyone can make their own (and it would probably cost $70-80, if what I'm seeing is correct.) They'll also be able to make their own years from now.


In fact, I don't even care if you put it up on GitHub, just put it somewhere where people can find the KiCad, gerbers, BOM, and assembly instructions ten years from now. Just put it up somewhere.

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Since I have a Quadra 950, I actually have an interest in this project :)


I have no money right now (the stupid shelter in place has turned the US economy upside down and inside out, and our total income is $0 for at least the next two months xx( ).  When I last powered it on (at least 4 years ago now, I think), it worked fine, so I'm hoping it'd still work fine now, but of course, there's no guarantee of that.  Therefore, if I might, I'd like to reserve a set for down the road when I'll hopefully have some money to pay with, which should be sometime during July, August or September of this year, when I'm hoping things here will be mostly reopened).



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Don't worry @CC_333, I understand. I have been in almost the same situation for the past year :cry:. I thankfully found something recently that'll keep me busy and afloat.


I'll keep the extra sets on hand until someone wants them. Don't worry, one has your name on it. In the meantime, if you want to try your luck with the old PSU, I would recommend using a power strip that has a switch on it (plug everything in and then switch the outlet on). That arcing sound when you try to plug it in "casually" doesn't seem right. 


In other news, I've had some issues with the AC board. As you can see from the previous pictures, there used to be an earth plane pretty much everywhere but on the DC side of the relay. Apparently this can cause issues and it's best to remove it. Thanks to alumbrado on r/vintageapple for suggesting it. I have since done more research on the matter and it is indeed not recommended to have one.


Here is the new current design (v0.6):





The minimum distance (clearance and creepage combined) between AC and DC is now 10mm. Apparently (and according to a post on this thread), the minimum safe distance for 240V AC (in this case 240V is critical, not 120V) is 5.5mm so there shouldn't be any issues. I am now sure that I over dimensioned pretty much everything. The minimum clearance between the AC tracks (Neutral, Phase, Earth) is now 4.5mm. But we're talking tracks, not plated holes, so this is well above the 'acceptable distance' of 1.6mm. I've also had to take another look at the original board because depending on the type of load (inductive, resistive...), snubbers may be required. Delta didn't use anything to protect the relay from the monitor, so it should be fine without it. 


I am still having issues with the cables for this mod. I've found the original specs: https://www.wontex.com/products_3_b.php?gid=7

but I can't find new cheap ones that aren't bigger... I am now considering using 18 or 20AWG. More to follow.


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I have good news. I was able to find cheap wires for both the logicboard harness and the AC input (AC board to ATX). 

18AWG for LB: https://www.arrow.com/en/products/1430-18-1-0500-004-1-ts/cnc-tech-llc

16AWG for AC: https://www.arrow.com/en/products/1430-16-1-0500-001-1-ts/cnc-tech-llc

Available in all colors, so the original aesthetic will be preserved. 


Black and red: 14ft each (that's 10x 40cm for each color)

Rest: 2ft each

-> price including terminals ($2.5 for 24): $16,52

Do you think it's too expensive?

Another option would be to skip buying new cables altogether and re-use the original cables. Unfortunately for me, I'll have to order new ones as I kinda damaged the original harness...


Technically the Becker also uses 18AWG for AC so you could theoretically use LB wires for AC. But for the price difference (80c), I'll sleep much better knowing that the AC wires are thicker. 


The 18AWG wires are a tiny bit smaller compared to the originals (16AWG), but they are more than enough (current wise) and they'll will fit better through the black cable tie thing. They're about 0.23mm smaller in diameter, which results in 5.5mm extra leg room! Awesome. The black cable tie thing is adjustable (it's just pretty much saturated with the OG wire config), so the harness will still be nice and snug. 


I'll update you guys with a BOM (list of parts) soon. 

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I have created a new version of the AC board with the filter at the input (instead of at the output). Any comments or remarks would be well appreciated. 

I'm concerned about the track lengths... The Neutral track (Net- (FL1-Pad2) ) is 13cm (5 inches) long. May be too much... What do you think?



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Well I've just bought a Quadra 950 that turns on for a second and then each second it drops power and fans spin down, next second up, then down.  Poor PSU must be suffering in there so I killed power quickly and started searching online.  And here we are!  Reading your journey from the first post to the last is a lot of fun - progress has been made for sure.  I am new to this project so am a little lost on where to start.  I like "step 1" but can figure most things out.  


Of course I've over in Australia so postage on anything is going to hurt.  The way this project looks now is :  You gut the Schwarzenegger size Delta power supply.  Install the AC and DC side to the exisiting chassis.  Take the internal components of a high quality ATX power supply and mount it in the Delta chassis also.  Connect everything and profit?  Hehe.  


I'll have to wait for photos of it installed to follow things but wow what a great contribution to the community sir BadGoldEagle

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Hey there. You guessed the steps right :smiley:. I'll come up with a more detailed guide later but that's pretty much it. 

At the moment I'm investigating the DC board clearances and I still have a few other small questions/issues before I can give JLCPCB the go ahead.


I've never sent anything to Australia but I think it'll still be cheaper than having boards made yourself (of course you'll still be able to do that if you want... I'll upload everything to GitHub once's everything done and tested). PCB Way was WAY overpriced and it still costs 30 bucks to have the boards sent out of China with JLCPCB (since the minimum order quantity for ONE board is 5, that makes 10 boards minimum and copper is heavy!)... 


A set will weigh 120g. It'll have some light padding but hopefully that'll help you estimate the shipping costs. Tell me if you're still interested in getting a set. 


Back to the Quadra.

Your 950 PSU exhibits the exact same symptoms as mine did after the recap. In my case, the 5V rail was causing this. I tried powering it on on its own with no load and there was 0v where there should have been 5. So don't worry, the logic board isn't to blame here. I had a professional PSU specialist look at the Delta unit and he couldn't find what was wrong with it... The diagnostic and the recap cost me a lot of money so I decided to cut my losses and start working on this mod. 

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  • 3 weeks later...

And the checks are done! Phew!


I am still not particularly proud of my fan circuitry. I am currently thinking about upgrading my dumb controller to at least PWM. But I am also tempted to go with a full-blown temperature controlled circuit that reuses the PSU's built-in controller... but for someone with limited electrical engineering background like me, that's rather complex. Here are my (rather basic) system requirements:

  • The minimum speed setting shall be controllable with a potentiometer or when possible trimmer.
  • The fan speed while unit is in operation shall be regulated automatically based on the PSU's internal temperature.
  • The actual fan speed shall be defined as the maximum between the temperature controlled speed and the minimum fan speed, whether the unit is on or not.
  • The fan shall be able to run at a fixed speed if the PSU's built-in controller is not plugged in. 

Truth Table:


Cold PSU


Quadra ON

Always on and at minimum

ATX controller OR minimum

Quadra OFF


ATX controller*

* May be used to cool down the PSU after the Quadra is switched off.

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  • 2 weeks later...

Proposed Comparator/Controller circuit:



I had to take into account the different 2/3-pin fan control strategies (namely, PWM and Modulated ground) for the ATX PSU fan connector because since this isn't standardized, it has to work with them all. That's C1, R5-8 (on the right) and Op Amp #3. The other three Op Amps are used to compare the Potentiometer fan voltage to the ATX PSU fan signal. For those with Op Amp background, there's two comparator and one follower setups. Two power transistors Q2 and Q3 will effectively switch the two fan signals either on or off based on the table in the post above. I added a slide switch to disable/enable the comparison circuit (it disables the LM324's Vcc input and the circuit will function like before ie Potentiometer control only). For those who don't want to bother with this whole thing, just short 5 and 6 on SW1. You don't even need to buy the switch, I'm currently thinking about adding pads like on the IIc to short those pins:



© Big Mess o'Wires


Edit: For once, it was easier done than said. Kicad has some built-in solder jumpers!


I'll double check everything again and I'll update the PCB. 


Edited by BadGoldEagle
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