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SE/30 - Design for Drop in Replacement Power Supply

(o';'o)

Active member
Hello All,

I am currently looking into designing a drop in replacement power supply for the SE/30 that would fit all of the major versions of stock PSUs. What I have currently found is that there appear to be three major versions: Two from Astec, and one from Sony. I was able to obtain one Astec and one Sony PSU, and JDW was kind enough to ship me the second Astec for me to inspect and get mechanical measurements. My aim to is create a single PCB version that would fit into all of the metal enclosures, would be easy to install (little to no soldering), and would not require a cooling fan.

I have a few questions that I'm looking to get some guidance on:
(Note that I have read through https://68kmla.org/bb/index.php?threads/modern-psu-for-the-se-30.30945/)

1) Is anyone aware of any other versions of power supplies that were used with the SE or SE/30 other than what I have pictured (Two pictures are screenshots from JDWs YouTube video)?

2) What is the necessity for providing separate +12V supplies for the disk and sweep circuits? I have seen some folk say there there is no issue with running them both from a single supply, but others have mentioned that there is potential for display artifacts when the disk drive pulls current. My initial thought, other than the visual artifacts, would be some concern about the sweep flyback circuit causing spikes to be reflected to the disk drive, which could cause errors or disk failure. (I realize this question has been posed in other threads, and that there is an isolation diode between the two, but I don't think I've read anything that was conclusive).

3) Some folks would argue that the stock PSU current capabilities are limited, especially if someone were to install upgrade cards. Does anyone have a measured value for what current rating would be required, given the worst case of upgrades? And would this only apply to the 5V supply, or should the +12V and -12V have increased ampacity? I'm looking for concrete, measured current values.

Many thanks in advance!

-Chris
 

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JdM74

Active member
Hi there. Yes, there is the one I call “The Made in Singapore” version. Worst of the lot. Their caps leak without fail…I have one that came out of an SE/30.

Astec is a better grade of bad and I’d take one of those any day of the week over the Singapore version. Naturally, Sony is the choice.

A drop-in replacement…sign me up!!
 

(o';'o)

Active member
Hi cooltr6,

Would you be willing to mail me this ‘made in Singapore’ version? I’m happy to pay shipping + a little extra for the inconvenience. I won’t need it once I have taken the necessary measurements and done a test fit with the new PCB, so I’d be happy to send it back when I’m finished.

I’m located in Seattle, WA 98122.

-Chris
 

JdM74

Active member
Hi Chris. I can certainly ship the PSU off to you, you pay for return shipping when you're done.

If you're taking physical measurements...all good. I did test voltages and whatnot. It seems to be pretty stable if you need it for those details as well.

Lemme know what you want to do and it shall be done.

Jason.
 

(o';'o)

Active member
Hey Jason,

Could you post a couple pics of your PSU to this thread? I will send you a direct message about sorting out the logistics for shipping, etc.

-Chris
 

JdM74

Active member
@(o';'o) Photos as requested. If there's another view you might need, let me know.

-j
 

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Juror22

Well-known member
one I call “The Made in Singapore” version. Worst of the lot. Their caps leak without fail…
I'm re-capping my second one of these - the first one was pulled from an SE and exudate from the caps had actually been leaking (slightly) out one end of the power supply! It now works great after the re-cap.
 

JdM74

Active member
@Juror22 I am glad to hear you're having a run of good luck with the two of yours. Unfortunately mine had a little bit more destruction due to the cap leakage that occurred. Mine came out of an SE/30 that had a good life and was well taken care of. Naturally, where one disaster strikes -- another is sure to follow...and it did. The logic board succumbed to cap leakage there too. A bad combination. 😁

I applaud the efforts of those who are looking to provide alternatives in drastic cases of irreparable damage or just simply bad builds. Another such effort -- ReActive Micro, who offers a Universal PSU Kit Apple II, II+, IIe, IIgs, and /// [and will fit Vulcan and InnerDrive as well]. All those folks doing this work...helping to keep our beloved Vintage computers alive for MANY years to come. ❤️
 

Juror22

Well-known member
I applaud the efforts of those who are looking to provide alternatives
Even though I've started re-capping some of my worst-case examples, I would be just as happy to fill the cases with new, replacement PSUs that came from a project like this thread is working to create, because I have several more SE and SE/30s that will eventually need a solution as well. If there is a possibility of elevating the power output (I've always suspected that the SE/30s probably just push the PSU harder, even without the additional cards that are inevitably crammed into them) it should be done. Nice job @(o';'o) for trying to gather some additional information on these requirements.
 

(o';'o)

Active member
@cooltr6 - Thanks for the pictures! It appears that the 'Made in Singapore' version is substantially similar to one of the Astec versions. I am currently waiting for this version to arrive from @JDW. I should have it in a week or so. Let's hold tight on shipping yours out until I have a chance to inspect this one in person.
 

(o';'o)

Active member
Hi @cooltr6 - I received the third power supply from @JDW and have confirmed that it is the same type as yours. Thank you for posting detailed pictures so I could verify.

I have completed the PCB design for V1, and sent it our for manufacturing. I expect that I should receive the shipment by the end of next week. See attached pictures for the 3D model. Take a look and let me know what you think. I would be pleased to hear any feedback for V2.

I didn't get much more feedback about what the max current rating should be for each voltage rail, so I decided to reasonably 'max' them out. The DC output current specs are as follows:

+5V 10A
+12V (Sweep) 2A
+12V (Disk) 3A
-12V 1.25A

There also wasn't much resolution regarding the isolated +12V outputs for the Disk and Sweep circuits. After inspecting the three factory power supplies, I found that they have a steering diode and output capacitor from the Disk supply to the Sweep supply. I believe this is probably to isolate any inductive spikes from the sweep circuit, but I don't own a SE/30 that I can look at the circuit on an oscilloscope. So, I figure the cost of one diode and one capacitor is minimal so there was little reason not to include them.

Once I have the PCBs back and populated with parts, the next step is to test these out in real computers. @cooltr6 - Would you be interested in being a tester?
 

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(o';'o)

Active member
I also discovered another part number for the SE/30 PSU while I was surfing the web the other night - PN: 661-0370. See attached diagram for reference. If anybody has one that they would be willing to mail me, I would be most grateful.

-Chris
 

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JdM74

Active member
@(o';'o) Heya Chris! Interesting that the Astec and 'Singapore' PSU's were the same. Their outsides differ, I guess the insides are close enough.

I've attached photos of the power detail tags found on both the Astec and Sony CR-44 power supplies. Your amperage numbers are a bit higher than what's considered "stock".

I'd certainly be happy to test whenever you get the boards back from manufacturing.

In response to your other more recent post -- P/N 661-0370, if memory serves is just a replacement part number and could be any of the three 'stock' PSU's. There was [and still is] differentiation between what comes with your machine originally and what is replaced.

Jason.
 

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JdM74

Active member
@codevonlux Ahhhhh. Very interesting. When I looked at the PCB in the “Singapore” model, I didn’t see a Hitachi marking. I’ll need to go back and take a peek at that.
 
In response to your other more recent post -- P/N 661-0370, if memory serves is just a replacement part number and could be any of the three 'stock' PSU's. There was [and still is] differentiation between what comes with your machine originally and what is replaced.
You are 100% correct. Apple only had one Power Supply Module part number 661-0370 that covered ALL power supplies used in both the Mac SE and SE/30. It's the OEM way.
 
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