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wierd_w

Measuring a PEB

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Hey folks,

 

I have decided to embark down a path of projects to benefit this community by making complete fully dimensional drawings for (and CAD models of) all the enclosures used by this system.  However, I do not own a PEB, therefor I cannot make such for that item.

 

Can somebody whip out some calipers and give me some dimensions?

 

 

What brought this on:

I have seen some suggested projects that would require this information (Laptop convert of 99/4A, new shell for 99/4A, cartridge replacement shell, etc..), and I have noted a lack of good dimensional drawings for these components. I happen to be a trained industrial draftsman, and can produce these for most of these items myself without help, but I do not own a PEB.

 

I also own a (cheap, Chinese knockoff) 3D printer, and I did some CAD experiments on making easily printed, "Interlocking" parts, that could be used to create printed versions of these items, with some effort.  This last bit is a moonshot, but the former I can totally do, no trouble.

 

If somebody has a PEB that is already taken apart, and has a pair of calipers-- Take some photos and scribble your measurements on the pictures and post them.  I will make CAD drawings.

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1 hour ago, wierd_w said:

but I do not own a PEB.

 

If you are anywhere near the Gettysburg, PA – Washington,DC – Baltimore, MD area, I could loan you a PEB for this purpose.

 

...lee

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Sadly no. I am landlocked in the most inconvenient place in the contiguous US states-- Central Kansas. Where there is neither culture, nor appreciation for old things.

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14 hours ago, wierd_w said:

Hey folks,

 

If somebody has a PEB that is already taken apart, and has a pair of calipers-- Take some photos and scribble your measurements on the pictures and post them.  I will make CAD drawings.

While I do have a 12" digital caliper, a lot of those dimensions exceed the capability, so for consistency I used a steel yardstick marked in 1/16" graduations.

This won't be pretty but ... here goes:

 

The PEB is a 3D rectangle with gross outside dimensions including molding of 17 3/8" L x 11 1/2" W x 7 1/8" H.

There are two "versions" (older style used here) - each has identical, gross outside dimensions with minor rear height modification of #3 below

and the power switch is rocker style not requiring the odd little metal mount seen in lower left pic of #1 below.

 

Major assemblies are:

1) A steel base of 17 13/16" L x 9 5/8" W x 6 11/16" H resting on 5 rubber feet/bumpers, each 3/4" x 3/4" square by 5/16" high. Fan in upper left is not stock PIC1

    The back is a continuation of that steel base to form an L shape. PIC2

2) A 4 1/16" X 7 1/2" PCB mounting 8 60-pin card edge connectors (these are effectively PC 8-bit ISA slots if you chop off 2 pins). Card slots are 15/16" center to center.

3) A steel card cage assembly that sits astride #2 above and mounts itself and the PCB to the steel base of #1 above, provides holes and space for cooling flow and peripheral stability. PIC3

4) A three compartment steel assembly (largest) providing rigidity for everything else to mount to, channels air flow,

    and forms front/side enclosure (receives #5 on top and #6 on front). Drive area is 4 7/8" W. Peripheral area is 7 1/2" W. Power supply area is 5" W.

    Power supply on right of picture is not stock. PIC4

5) A steel lid with plastic trim of 17 3/8" L x 10 15/16" W x 1/2" thick.

6) A plastic face plate with cutouts like #4 above of 17 3/8" L x 7" W x 1/2" thick. Provides light pipe mounting to peripheral cards, FDD cutout, and power switch access.

 

#3 is next to impossible to break down and dimension for you, but I'll begin with #1 above and come back and edit this reply with remaining dimensioning.

If none of this is usable, stop me now as this has already been a 1/2-day project ... not straightforward at all. 😁

 

Doug

 

 

 

PEB Base.JPG

PEB back.JPG

PEB Card Cage.JPG

PEB major.JPG

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This is very useful!

 

If possible, i would take your images and highlight areas i would like measurements on.

 

I can actually reverse engineer a flat pattern for the sheet metal components if i get some key measurements.

 

 

Since this is sheet metal, I need some small bits of detail not provided-- I need nominal thickness of the material, and the outside corner radius of the bends.

Edited by wierd_w
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So, are you thinking of making a complete PEB case?  It would be amazing if someone did that.  Something that would hold a modern PSU (i.e., quiet-ish), possibly smaller (maybe horizontally?) and colored the same color.  🙂

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With full dimensions, I could make a full size flat pattern print (since I have a large format printer. 😉)), then I could use spray adhesive to stick it to the sheet metal, cut it, and manually bend it with some forms.

 

With access to dimensions of the plastic outer housing, I can design modular 3D printed "Snap together" parts.

 

AND-- with the drawings and such made available, other people could do the same.

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2 hours ago, cbmeeks said:

So, are you thinking of making a complete PEB case?  It would be amazing if someone did that.  Something that would hold a modern PSU (i.e., quiet-ish), possibly smaller (maybe horizontally?) and colored the same color.  🙂

 

There is more to this than just building a box. I've gone through the process.

 

Some issues:

 

1. The backplane is the critical part.

2. Voltage regulators on existing cards really need 8V and 16V. More risk, or more components.

 

1. Why make a completely new P-box when there are PC cases already? You need a backplane from a PEB. I have seen it done and working. (There is a bad scenario if the mu-metal at the back is bent out of shape.. and it bends easily) Or tackle making the backplane only. There, you'll find that the connectors are quite hard or expensive to source, but check with Ksarul about that.

 

Then you must be sure that cards are mechanically locked down. If you get the mechanical wrong here, where TI got it pretty solid, and there is a chance your cards can become unseated - in transit, or while powered up - you risk frying your cards.

 

Of course, while doing all this, you are slacking off the mechanical and RF protections TI originally built into the P-box. Sure, those were overkill, and both earlier and later PCs didn't bother with that. Still, everybody needs a locking mechanism for card slots.

 

2. But having seen it done, I really wonder about voltage regulators. I know folks have outright removed all the regulators. The power supply  5V and 12V rails are used to directly power cards. A lot of good cards have been fried this way from the simple mistake of plugging the modified cards into a stock system. 

 

I think we have all learned the hard way what happens since Jaime removed the voltage regulator entirely from nanoPEBs. (I have fried 2 nanoPebs where a voltage regulator would have helped. In addition to frying 2 CF7+s with visible sparks from improper grounding, it's not a cure-all or surge suppressor.)

 

For regulation, you really need the 8V and 16V rails that exist in the Pbox, not the 5V and 12V rails you get from a modern PS. So you're looking at finding a custom supply, or adding a boost converter that can reliably source enough current. 

 

The 8V rail in the Pbox is just enough to guarantee stable operation of a 7805 regulator.

 

You could put everything on the 12V rail. Then you have the risk of scorching cards from the extra heat, plus the RS232 12V would still not work. 

 

Experiment

 

I recently used my bench supply to test the regulator on a CF7+ from a range of 4.5 to 8V for current draw. This device can't get its 173 mA needed even at 7V.  I read the 7805 datasheet (TI's version) which says it can provide current at 6V, but requires 7.5V to properly filter ripple voltage. You can use 6V from battery DC sources though.  I didn't find that 6V or even 7V were enough to give enough current to the CF7+. 
 

Similarly, I measured the current across substitute 5V and 12V LDO regulators in the RS232 card, connected to the 5V rail, and they were not turning on at all at 5V. This is entirely predictable from the datasheet I-V curve. They need  5.6V and 12.6V or so. Also some low ESR capacitors, and 7V in to filter ripple voltage.


 

These problems are why folks have removed their voltage regulators entirely.

 

Notes

 

As a first guess, here are some less expensive boost converter ICs that got up to 1A. Not enough for the whole Pbox. I didn't shop for a ready-made solution.

https://www.mouser.com/Semiconductors/Power-Management-ICs/Voltage-Regulators-Voltage-Controllers/Switching-Voltage-Regulators/_/N-668jt?P=1z0wd73Z1z0wadvZ1z0wbyrZ1z0w2kxZ1z0wd5eZ1z0wbdjZ1z0w1tnZ1z0z63xZ1z0vndwZ1z0vnclZ1yjepwwZ1yjeqg2Z1yjeqouZ1yjeqkk&Keyword=boost+dc&Ns=Pricing|0&FS=True

 

 

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I was just thinking along the lines of a replica PEB instead of a standard PC case.  Doesn't really matter to me that much as I own a PEB.  Although, I would love a replacement lid as mine is scratched up and the posts are missing.

 

That's interesting about the regulators.  I wonder if that's my my 2016 SAMS card gets really hot on the 7805.  I mean...REALLY hot....as in I lifted the card up and now I have a blister because of it.

 

Then again, I forgot to put a heat sink on it so my fault.

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Replica PEB was the direction I was going as well.  If the card slot connectors are a standard pitch, sourcing them shouldn't be "THAT" hard I don't think... 

For RF Shielding, I was going to print/assemble the outer housing plastic, then liberally spray the inside with conductive paint. (several layers)

 

Since the cards that go into a PEB have that plastic protective housing on them (for commercially made originals anyway), getting the spacing, and retention system right is an absolute must. That means "Faithful Reproduction".

 

For power, I was going to go hunting for the correct rail voltages when shopping for a supply. 

 

 

The hardest part (for me) I think, is gonna be raising those sheet metal bosses that the inner cage sheet metal retainer rests on.  I might end up printing plastic feet to hug  tall brass stand-offs instead.

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40 minutes ago, wierd_w said:

Since it was mentioned---

 

Is the pitch on the 60pin PEB slot 2.5mm?  If so, then would it be possible to source nintendo/famicom slots?

 

https://www.aliexpress.com/i/32827561249.html

Probably not. Two reasons.

 

A. TI worked in imperial. 

 

B. 2.5 mm is a weird pitch that's basically only used in the NES. The Famicom uses 2.54mm connectors, which is  0.1 inch and quite standard for through-hole electronics.

 

 

That said... famicom cart connectors are almost perfect. It looks like they aren't thick enough, though. I just did a board comparison, and while FC carts and PBox cards use the same pin count and .1" pitch... PBox boards are about twice as thick as FC carts.

(I KNOW there's calipers in this house to get actual board thicknesses, but I cannot find them.)

 

 

Frustratingly, GENESIS cartridges are the right board thickness, but have four more pins. That's close enough to be really tempting, but wildly dangerous for any card that isn't mechanically guided into place. No naked PBox board would ever be safe, and I wouldn't place bets that all clamshelled boards would fit tightly enough to land on target in the connector.

Edited by JB

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That's unfortunate. FC slots are inexpensive. Often though, thicker cards can be inserted, since there is give in the fingers. The width of gap between the plastic lands inside are the major hurdle there.

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Genesis slot huh..

 

what if a 3d printed spacer was inserted?  Then it would be impossible to insert the cards wrong, even with the longer slot...

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That's a really good idea, and I don't know why I didn't think of it!

 

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Never found the calipers.

Internet says that THIS is a match for the Genesis, and that's got dimensions.

 

Seems like you wouldn't even really need a 3D printer. Just a sheet of plastic the right thickness to cut chips off of, and maybe a drop of superglue to lock it down. Though I suppose that when you got one, you may as well use it.

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Here we are...

 

Prototype Genesis slot spacer.

 

Should cover the bottom 2 finger widths (4 pins) of the slot, wrapping around the outer perimeter of the slot for alignment.  Print with the flat wall side down so that there is no bridging.

 

genesis_slot_spacer.thumb.png.9ddfede808753a8c76a59ae7e70dbb47.pnggenesis_slot_spacer.stl

Edited by wierd_w

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inches??

Drawing was totally in mm, and I set my CAD export as mm... will double check.

 

Yup.. Modeled in mm, like the drawing.

 

 

genesis_slot_spacer.thumb.png.b1e9eb8ea45b60417ff580e732dd1a94.png

 

 

Or do you mean the measurements made on the PEB's geometry above?

 

The original part was designed by US engineers, and so everything should come out to even multiples of 1/16 (or 1/32)".  I will include both sets of numbers when I make proper prints of the drawings.  For now, I am still in the data collection phase.

Edited by wierd_w

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On 11/14/2019 at 11:26 PM, wierd_w said:

Since the cards that go into a PEB have that plastic protective housing on them (for commercially made originals anyway), . . .

 

Not that it is particularly important for this spacing discussion, but the protective housing on those originals is actually metal.

 

...lee

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Interesting; I wonder what TI was thinking there?  It would have radically increased the costs of the peripheral cards...

 

 

In other news, Helocast has been extremely busy feeding me with dimensional data. I nearly have all the data I need for the "outer" sheet metal component.  Just a few hole locations and some slots left.

 

Here's a pretty picture of the work so far. (I also have a work in progress draft sheet, but I don't want to release prints until they are complete. When I release them, I want them to be accurate and useful.)

 

PebOuterWIP.thumb.png.2b6793e84e53b3774d898785d17f7817.png

 

 

 

Be sure to tell Helocast how awesome he is for taking the time to send me the data!

I know all about how painful it is to try and collect it without good tools in hand, and he's been going at this like a champ.

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52 minutes ago, wierd_w said:

Interesting; I wonder what TI was thinking there?  It would have radically increased the costs of the peripheral cards...

My best guess is the gut speccing the PBox system was freshly transferred in from the military hardware division, and was still designing hardware that could withstand a russian bombing.

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