groupDIY 500 series mechanical specifications

[ruffrecords]

This is a placeholder for the idea of creating a grouopDIY mechancial spec for 500 series modules that properly takes into account things like the relationship of a module pitch to front panel width etc etc etc.

I decided to put it here rather than the Drawing Board which is really for analogue design

So I guess we start with gathering all the available specs.

Cheers

Ian

 

[sahib]

VPR Alliance module data/specifications.

https://medias.audiofanzine.com/files/api-vpr-500-spec-479213.pdf

These are my sketches from the time Jeff, Volker and I used to do the GDIY 51x.

The module (centre) mounting hole pitch is standard 38.1mm (1.5").

This is also the theoretical module front panel width. However, in practice this should be slightly narrower so that the modules can fit side by side. Otherwise they will start to stagger and probably after 5-6 modules the mounting holes will not align. I normally make it about 0.5mm narrower.

Below sketch is for both front and rear. However, the three vertical holes on the left and right only exist at rear for rear panel mounting.

118.42mm is the rack mouth opening. This is about 4mm wider than the module card height. One can make it a millimetre or so narrowerr but the other two dimensions are fixed.



Below sketch is view from front, showing that the card edge connector is positioned 11.12mm to the left of the module centre.



Card edge connector used is 3.96mm pitch, 15 pin (18 pin for GDIY 51x) As I mentioned in another thread I think API used EDAC which is much more expensive than Oupiin or Pinrex.

 

[MidnightArrakis]

The following is apparently the original "source of confusion" about the -- 1.50" -- dimension concerning the "500-Series" format:

• In other threads within this forum, it is stated that the API "500-Series" front-panels themselves are 1.50" wide and then their mounting-hole pitch is just a hair more than that in order to accommodate a tolerance clearance. Does anyone know or have any idea of what the actual API "500-Series" mounting-hole pitch is? That would be most useful to actually know.
• Yet, others declare that the mounting-hole pitch is 1.50", so then the front-panel sheet-metal is somewhat LESS than that in order to accommodate a tolerance clearance.

>> WHICH IS IT? Does anyone "really, really fer sherr" know???

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[MidnightArrakis]

Below sketch is view from front, showing that the card edge connector is positioned 11.12mm to the left of the module centre.

View attachment 144271

Card edge connector used is 3.96mm pitch, 15 pin (18 pin for GDIY 51x) As I mentioned in another thread I think API used EDAC which is much more expensive than Oupiin or Pinrex.

>> Your above sketch is missing a "REFERENCE" dimension. Which would be: -- What is the dimension from the left-side of the PCB over to the -- vertical long red line -- shown to be in "approximately" the middle of the PCB? Unless your sketch is not drawn to be exactly "to scale", everything visually appears to me to be slightly offset to the left-from-center. Can you provide me with that "REFERENCE" dimension? THANKS!!!

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[Rob Flinn]

I haven't looked at this document too closely, but there may be some information of relevance in it.

https://www.steampoweredradio.com/pdf/api/api 1972 catalog.pdf

 

[MidnightArrakis]

I haven't looked at this document too closely, but there may be some informa`tion of relevance in it.

https://www.steampoweredradio.com/pdf/api/api 1972 catalog.pdf

Well.....by going completely through this catalog PDF file, it did basically confirm that the API front-panels are -- 1.50" -- wide. But, what really did surprise me is their mechanical drawing of the front-panels are shown as being -- 0.187" -- thick and not the 0.125" thick that we Americans now use or the 0.118" (3mm) thick panels that our European cousins use. So.....that was different.

I am just hoping that -- @sahib -- will be able to provide me with the "REFERENCE" dimension I have requested before too long.

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[sahib]

>> Your above sketch is missing a "REFERENCE" dimension. Which would be: -- What is the dimension from the left-side of the PCB over to the -- vertical long red line -- shown to be in "approximately" the middle of the PCB? Unless your sketch is not drawn to be exactly "to scale", everything visually appears to me to be slightly offset to the left-from-center. Can you provide me with that "REFERENCE" dimension? THANKS!!!

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The dimensions I have given are the critical dimensions. For PCB the designer has to work it out himself/herself.

However, if you look at the first sketch the rack mouth opening width is 419mm. Now, obviously the backplane PCB would have to be slightly narrower than that, so that it would fit in.

Otherwise you are right that a proper design drawing for manufacture would require a reference on the left.

If one decides to use my sketches then the horizontal dimensions would start from left with 0, then 7.5mm for the flange edge. If you leave 1mm clearance for the backplane then the LHS edge of the backplane starts at 8.5mm.

Here is the rear view of our rack drawing.

 

[Brian Roth]

The widely circulated VPR Alliance docs from API show a panel 1.50" wide, 5.25" tall and 0.125" thick. No tolerances specified.

Perhaps someone with a REAL API rack can measure the spacing of the threaded holes.

Bri

https://service.apiaudio.com/documents/VPR-Alliance-Program-Outline.pdf

 

[MidnightArrakis]

Am I the only person on this forum who can create a PCB-fabrication/mechanical design fabrication document like these?.....











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[Brian Roth]

Am I the only person on this forum who can create a PCB-fabrication/mechanical design fabrication document like these?.....

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Probably not. But, if you don't know key details of the API dimensions, you're just wasting your time. <g>

Bri

 

[MidnightArrakis]

WOW!!! -- While going through an old "conversation" that I had with another member of this forum that is 29-pages long about a year ago, I discovered that I had already possibly created a document drawing that this thread is looking for!!! Please review take a quick look at the image I have posted below and also carefully reviewing the attached PDF file, which will allow you to zoom and pan in and around the drawing more easily. Hope this works!!!



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[Brian Roth]

OK, the VPR Alliance docs from many years ago and issued by API clearly say the panel width is 1.500". If it's not 1.500" it does not meet the VPR specs.

So what is the center-center spacing of the mounting holes and the center-center spacing of the EDAC connectors? At 1.500", a few slots will work, but eight or ten slots at 1.500" spacing will require a hammer to insert the modules.

Bri

 

[sahib]

The widely circulated VPR Alliance docs from API show a panel 1.50" wide, 5.25" tall and 0.125" thick. No tolerances specified.

Perhaps someone with a REAL API rack can measure the spacing of the threaded holes.

Bri

https://service.apiaudio.com/documents/VPR-Alliance-Program-Outline.pdf

Module mounting hole pitch on horizontal and vertical axes are fixed and you do not specify tolerance for these. Instead you'll ask your metal fabricator what tolerance they work to and if this is acceptable to you. For example the metal fabricator I use has a tolerance of +-0.1mm. So this is another reasons why the module faceplate width has to be narrower than 1.5" so that it also accommodates these errors. However, making the module mounting hole diameter slightly larger will also accommodate these errors.

I do not have an API module but perhaps someone who has could measure (with a calliper) the width of a few faceplates to see what tolerance API has. However, as I mentioned before I make our modules about 0.5mm narrower which comfortably covers all eventualities.

 

[jsteiger]

The rack hole spacing is on 1.5" centers. Modules must be made a little less or they will not fit as Brian mentioned. I have 2 early '70's API modules handy and those are 1.49" x 5.25".

 

[JMan]

So it would seem that a 0.01" tolerance was given only on the width, but no tolerance on the height. Were those modules designed for a standalone lunchbox? Rackmount 500 chassis? Console? I could see a standalone lunchbox not needing the tolerance where a rackmount chassis might.

 

[john12ax7]

The vertical 5.25" should also be undersized, as should all rack gear.

And one also needs to account for powder coating if used.

 

[Brian Roth]

I totally agree that panels need to be slightly less than 1.5" wide. I was merely quoting the specs published by API to "qualify" for their approval of third-party modules.

Bri

 

[MidnightArrakis]

The vertical 5.25" should also be undersized, as should all rack gear.

And one also needs to account for powder coating if used.

[The vertical 5.25" should also be undersized, as should all rack gear] -- YOU ARE RIGHT!!! -- The entire "500-Series" set of mechanical dimensions ARE FLAWED TO BEGIN WITH!!!

If you are going to have front-panels being specified as being 1.50" wide, you -- CAN'T HAVE THEM -- also being on a 1.50" pitch!!! PERIOD!!! As I have written in some of the other threads pertaining to this specific topic, by following the "somewhat industry standard" rack-mount tolerance of under-sizing sheet-metal pieces by -- 0.030" -- that will give you a front-panel width dimension of being 1.47". Even with using powder-coating as a finish, that amount of tolerance would easily accommodate two side-by-side panels.

[The vertical 5.25" should also be undersized] -- YES!!! - When I saw the API datasheet specifying its "500-Series" panel-height as being 5.25", I immediately thought, "JUST WHAT THE F**K WERE THEY SMOKING"!!! -- There is no friggin' way that a piece of equipment going into a 19" rack would be specified as being 5.25" high!!! However (and, I am only guessing here), this dimension may have been a mistake on their part, as the "500-Series" modules were designed to be mounted into a -- portable -- "Lunchbox" enclosure and not into an actual rack-mounted card-cage chassis. I don't really know, though.

In any case.....YES!!!.....the front-panel of a "500-Series" module should actually be only -- 5.22" high -- as conforming to the basic rack-mounting 0.030" tolerance under-sizing.



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[JMan]

There is no friggin' way that a piece of equipment that would be going into a 19" rack would be specified as being 5.25" high!!! However (and, I am only guessing here), this dimension may have been a mistake on their part, as the "500-Series" modules were designed to mounted into a -- portable -- "Lunchbox" enclosure and not into an actual rack-mounted card-cage chassis.

This was my thought as well. The standalone lunchbox would not really need to worry about accommodating anything immediately above or below, and I imagine this is why there is no margin on the panel height on those modules Jeff has.

 

[MidnightArrakis]

This was my thought as well. The standalone lunchbox would not really need to worry about accommodating anything immediately above or below, and I imagine this is why there is no margin on the panel height on those modules Jeff has.

See my newly added front-panel mechanical detail drawing above that I had included just moments after you posted your response.

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