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500ppm LCR Meter case drawing incorrect.

Equipment, circuits, projects, procedures

Postby james hill » Sun Jun 23, 2013 12:00 am

I appears that the drawing of the case for the 500PPM LCR meter that is available for download is incorrect.

The BNC end is correct.

The USB socket cut out is far to high, the bottom of the cut-out should be approximately on the same plane as the bottom of the switch.

@Elektor, please could you remove or revise the drawing?

I rather stupidly spent time cutting the holes trusting the drawing. I now have lost an hour of my time and a case end plate.

James
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Postby snoopy_94 » Wed Jul 03, 2013 12:00 am

Hello James,

Sorry for this mistake.
Corrections are described in the July & August magazine.

You can also find corrections here
http://www.elektor.fr/forum/forum/publications-d-elektor/lcr-metre-0-05-(3-047-4-047-5-2013)/erreurs-et-corrections.2473102.lynkx

Find attached the new drawing

Jean-Jacques
Attachments
110758-per-age-arri-reMK2.png
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Postby brendan hughes » Sun Jul 14, 2013 12:00 am

Unfortunately I also made this mistake. I had downloaded the most recent drawings from:
http://www.elektor.com/magazines/2013/may/500-ppm-lcr-meter-(3).2457846.lynkx?tab=4

As of today (14 July), they have not been amended. Whilst I agree that it is not possible to directly amend magazine articles and a later amendment needs to be published, surely downloadable files can be directly amended?

However, many thanks for a great project.

Regards

Brendan
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Postby thijsbeckers » Mon Jul 15, 2013 12:00 am

I apologize on behalf of my colleagues. Corrections have been started, but due to distractions and priorities this hasn't been updated yet. I've urged to update the file.
Awaiting the update, here's a drawing of the updated drillling template:
Attachments
110758-Drilling-template.png
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Postby ricks » Mon Jul 15, 2013 12:00 am

Hello,

I did not even require the template to determine the cutouts positions. All I did was install/slide the assembled pcb into the lowest chassis extrusion groove with one end face plate installed at one time. I drew the switch, USB conn. outlines against the back of the faceplate with a permanent marker, first the USB then the switch thereafter. I then proceeded to do the drill/file work on the inside face as not to scratch the outside face. Then I did the same for the other end, the BNC & LED holes. Well I anticipated this method, thus I installed the green LED first before installing the BNC's. It is certainly easier, if you have a drill press and some good small files (rat-tail, flat, triangle).
I bought 7mm spacers for the display and used an extra one that I filed down to 5mm for the pcb grounding to the chassis.
You need a flat head screw with countersink, for ground the pcb to the case, as the screw head will interfere with the plastic end moulding, if it is not flush with the Alum. surface.
I machined the top plate for the LCD etc. I had to file down the 7mm spacer to get the LCD surface to be flush with the back to the alum. plate, so all the spacers need to be 5mm not 7mm as the BOM shows.
So all done now, except for a SW update to fix reported short ckt TRIM problem.

Cheers
Rick
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Postby eguy » Mon Nov 11, 2013 12:00 am

What is this reported short ckt TRIM problem?
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Postby eguy » Mon Nov 11, 2013 12:00 am

My impression is that the templates for cutting out the holes in de end-plates of the housing are poorly designed. First of al in this case (sic) it makes no sense to give the dimensions in 0,01 mm. With professional equipment you might get a precision of ±0,1 mm and with semi-professional equipment you are lucky to get ±0,5 mm.

Further it is clumsy to give dimensions from centre-lines. If one marks a centre-line first (inaccuracy 1) and uses that for the final marking (inaccuracy 2) the inaccuracy doubles.

Further there are all sorts of mistakes. Some of them can cause real problems. For example:
- The dimensions of the little switch are (in my case) 7,6x4,9 mm. With 0,5 mm space around the hole should be 8,6x5,9 mm. On both drawings above the hole is 9,0x5,0 mm. This width is certainly not sufficient!
- As the bottom of the little switch is 0,5 mm higher than the bottom of the usb-socket (becase the switch is mounted in a tiny metal 'clamp'), and with equal free space around, the same should apply for the hole. In Jean-Jacques' drawing above this is 0,65 and in the drawing of Thijs Bekkers it is 0 mm (zero).
- The diameter of the green led (front) is 3,15 mm. With a hole of 3,5 mm the space around is 0,175 mm. One has to be very lucky to get away with that.
- This same led is mounted in a little black housing which sticks out over the front edge of the print. Because of this the print can not lie flush against against the front plate and sticks out of the back of the housing.

My advise is to measure your own circuit before making any holes.
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Postby snoopy_94 » Mon Nov 11, 2013 12:00 am

One hundredth of mm dimensions are due to the inch/mm conversion; It must be adapted to the actually used tools

I give dimensions from centre-lines because the PCB width is very dependent of the manufacturer (i.e. the de-panelization tools used).

For the switch, the level dimensions are 6x3mm, so a 9x5 mm hole is sufficient!

The position of the green led is not very accurate having regard to the manner in which it is fixed!

Jean-Jacques
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Postby eguy » Mon Nov 11, 2013 12:00 am

About the centre-lines I can follow your reasons. But nowhere is indicated that these centre-lines are the centre-lines of the print.

Indeed, the rocker dimensions are 6x3 mm, but not only the rocker but also the housing of this switch (7,6x4,9 mm) extends outside the back border of the print (see photo - bottom view). In fact, as I mentioned in the post before, also the print itself extends outside the back of the housing.

I don't understand what you are saying about the position of the green led (I am sorry, my French is worse than your English). It is firmly attached to the print, so the hole in the front precisely determines the position of the print.
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IMG-1926-CU-408x733-q30.jpg
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Postby snoopy_94 » Tue Nov 12, 2013 12:00 am

Indeed, the rocker dimensions are 6x3 mm, but not only the rocker but also the housing of this switch (7,6x4,9 mm) extends outside the back border of the print (see photo - bottom view). In fact, as I mentioned in the post before, also the print itself extends outside the back of the housing.

The Hammond 1455L1601 housing consists of a 160.00 mm body in extruded Al, two Black plastic bezels and two Al end panels.
The PCB has a length of 159.9mm. The bezel pushes aside the panel of 1.4mm from the edge of the body. The body of the switch exceeds approximately 1.5 mm from the PCB. So "le compte est bon": 159.9 + 1.5 = 160.0 + 1,4
You can also add 0.1 mm in the panel mounting in the bezel...

I dont understand what you are saying about the position of the green led (I am sorry, my French is worse than your English). It is firmly attached to the print, so the hole in the front precisely determines the position of the print.

You are right, but only after soldering the two pins of the led. Before soldering you can move the led as the mounting holes are larger than the diameter of the wires.

My English is not so good and I use translators...

Jean-Jacques'
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