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BadGoldEagle

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

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the black cable tie thing


That's called a "grommet" in English, ich hab kein Idee auf Deutsch, schade

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What other machines would this adapter be compatible with?  ie, use the same pinout as the Q900 & 950?

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Hallo Bunsen :)

Thanks a lot for pointing out what it's called. The documentation will look a lot more professional now.

Zur Info, diese Dinge heißt 'ne Durchführungstülle. En Français (I'm a french dude living in Germany after all...), ça s'appelle un oeillet ou bien un passe-fil...

 

And yes, this mod is only compatible with Quadra 900/950s as they are (AFAIK) the only Macs with a 24 pin Molex Mini Jr (ATX motherboard) connector.

 

In other news, I've had to scrap the previous fan designs (they weren't compatible with high wattage fans and wouldn't work with all PSUs...).

It's now fully PWM and has a thermistor for fan control. A LED lights up once the thermistor reaches a temperature of 80°C/176F.

It's still work in progress but it's lookin' good!

809954864_Bildschirmfoto2020-06-01um11_25_14.thumb.png.6e70e8c88160ea79b5313a973823d0b1.png

 

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Good looking schematics! (to at least a laymen like myself).

Your revitalizing work with the Quadra 900/950 PSU makes me want to pursue my quest for a Quadra 9XX even harder than before! Thank you! :-)

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I've had to revise the fan controller bit again...

1422489788_Bildschirmfoto2020-06-11um12_34_16.thumb.png.49921237ecd63b1d9eb9cb8db72c3fa5.png

 

Big thanks to the guys over at eevblog.com for their help. Although this still hasn't been 100% approved/verified, it's looking pretty good now!

We've mostly redesigned the LED controller circuit

        - Now we won't be frying op amps with voltages that are too high at the inputs (updated R8 and Vcc for U1).

        - I've switched to an LM393 (U1)as this is a proper comparator. The 358 wasn't.

        - Inverting Schmitt Trigger built-in (R5, R6, R11, R12). LED will light up at 84°C and will turn off at 79°C. Just like your engine waring light, it should never light up. If it turns red, please stop carefully and contact your nearest service center (i.e. me).

 

FYI

If you don't want temperature control just remove TH1 and replace it with a 10k resistor. 

If you don't want the Overheating indicator circuit, just leave R5, R6, R8, R9, R11, R12, U1, Q3 and D1 out... this is not recommended but the fan will still work without it. Leave those components out at your own risk.

 

 

Edit/PS: I'll probably buy a bench supply and a breadboard to test this circuit before I send the boards to production...

Edited by BadGoldEagle

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So, 2 weeks ago I've acquired a Quadra 950 Workgroup Server 95 and happy as a clam with the thing. I managed to score 8x4meg parity SIMMs on German eBay, which I plugged in impatiently. Well, you can guess the final outcome. A poof, a small mushroom cloud and some searches later I end up in this post. Truly awesome work @BadGoldEagle! And I'm really curious to the current status of things as I'd very much be interested in a way to get her running again. 

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@mietek sure thing... and that makes 10! Now, unless someone wants to buy 5 more, I'll stop the "pre-order" here. 

 

@Ton I feel your pain. It was pretty much the same thing for me but instead of RAM that was with the DOS card. And the damn PSU also tried to kill me (to be honest it was probably my fault).

 

I'm really starting to think there aren't any original working PSUs left...

 

And now, for the less fun part. A couple of weeks ago while casually browsing the web, I noticed that the MIC502 supplies aren't as high as I initially thought. I'll have to rethink the fan controller yet again (only for the 5th time). This on top of other life related issues, Apple ditching intel (which in itself almost caused me to fall into a depression), lead me to pause this project for a bit.

 

I need to sort out the life stuff first, but when I'll get back to it (hopefully in the next couple of weeks), I'll most probably pay someone to design the new circuit for me. I just can't handle another failure emotionally. This time, I'd like to use a 555 PWM generator type of circuit, but I can't figure out which one (there's at least 4 different variants) to choose. I'd like it to be still temperature controlled, and to have a minimum speed threshold (duty cycle) of about 40% so that the fan can't possibly stall. 

 

More to follow...

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So, I've opened the Quadra's case and power supply. The latter looked OK-ish, but on the motherboard something caught my attention. So, the first repair job is on the list.

 

Question; would I need to replace all of them, or will replacing the one that blew be enough?

 

Also; why did this one blow up? Wouldn't want to mindlessly replace this one only for it to be blown up again the next time. 

 

NWPscer.jpg

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When you're dealing with tantalum caps, only replace the ones that are damaged. The rest of them (for now at least) are ok. 

I don't remember on top of my head what value that cap was and my 950 is currently buried under a pile of stuff... Maybe someone else can help?

 

I think your PSU is what blew that cap.

Edited by BadGoldEagle

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On 6/26/2020 at 11:42 PM, Ton said:

So, I've opened the Quadra's case and power supply. The latter looked OK-ish, but on the motherboard something caught my attention. So, the first repair job is on the list.

 

Question; would I need to replace all of them, or will replacing the one that blew be enough?

 

Also; why did this one blow up? Wouldn't want to mindlessly replace this one only for it to be blown up again the next time. 

 

NWPscer.jpg

So I had the same thing happen to one I just got in the mail.  Please see my threads...

 

 

 

You should find these helpful.  

 

I was able to see the remnants of markings on my burnt cap and was able to determine it was this: https://www.ebay.com/itm/10pcs-T491C106K016AT-KEMET-Tantalum-Capacitor-16V-10-10UF-SURFACE-MOUNT/313012284846?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

 

I ordered it and soldiering station but I have not replaced it yet.  I did retrobright the plastic pieces of the case and they came out really good.  Putting out a blog/video series on it which I will post here and r/vintageapple when complete.  Hopefully its done this month or next.

 

As far as BadGoldEagle's PSUs, I would really like to get one but I THINK mine is working fine.  I spoke with someone who is electrical engineer who does not think my PSU blew it.  I hope he is right.  

 

Please let me know how you repair goes and I will you too!

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On 4/30/2020 at 7:54 AM, BadGoldEagle said:

New pictures!

 

DC_v07.thumb.png.4806211735d7ab4a3ed1d6c31b9e03a5.png

 

AC_v08.thumb.png.3149679419208e18d6ce4bdf741c7832.png

 

Final checks are still in progress... but the new AC board design is now much "safer". 

BGE:  Sorry, I haven't been following this thread closely as I should have been.  Are you offering to sell PSUs or the parts and instructions for us to mod our PSUs?  

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On 7/1/2020 at 5:05 AM, BadGoldEagle said:

@olliec420 Parts. 8 bucks would be a little too cheap for a complete mod... those boards will be BIG.

Instructions/files will be free once I finish it. Hopefully I'll have a new schematic ready next week.

Ahh ok very cool.  I definitely want a parts kit too when available.  Thanks for all the hard work to keep these old beasts alive! 

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The real hard work would have been trying to fix these old beasts, not gutting them... but at least, like Geekdot said, it’ll run cooler, be more reliable and easily repairable in the future...

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