AXE033 faulty after redrilling

Technoman

Senior Member
Hi,

As I wanted to install the AXE033 LCD display on a stand, I re-drilled the 4 mounting holes up to 3 mil.
Instead of the plastic spacers, I will use long metal screws, plastic spacers and nuts.

I checked before if there was no track being affected on the controller and LCD boards. It seems not!

It doesn't work any more!

I wonder if the LCD board (1602...) is a 4 layers PCB. As the drilling remove the plated copper there might be a cut connection (GND?).

Any idea?
 

BESQUEUT

Senior Member
I wonder if the LCD board (1602...) is a 4 layers PCB. As the drilling remove the plated copper there might be a cut connection (GND?).

Any idea?
Not 4 layers, but maybe two... And it may also be sensible to vibrations...
If holes were platted, this may be the GND connection between two faces...
Maybe you can publish close pictures (both faces). (and some from a not modified board to compare...)
 
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nick12ab

Senior Member
In what way doesn't it work any more?

Character LCD module PCBs are usually 2 layers. At least if the manufacturer wants to remain cost competitive.

Have you tested the LCD module and AXE033 PCB individually?
 

Technoman

Senior Member
@BESQUEUT : I don't have a camera with a good close up lens. On both side of the LCD module it seems the holes are electrically separated from the ground plane.

@nick12ab :
... tested the LCD module and AXE033 PCB individually?
No, not yet.
The first line has every dots on and nothing on the second line. No more message is displayed.
Before the re-drilling I closely looked at both PCB. Only the LCD module has some plated mounting holes, so I supposed that was the root cause of this issue.

My second AXE033 works perfectly with the same program.
 

rq3

Senior Member
@BESQUEUT : I don't have a camera with a good close up lens. On both side of the LCD module it seems the holes are electrically separated from the ground plane.

@nick12ab : No, not yet.
The first line has every dots on and nothing on the second line. No more message is displayed.
Before the re-drilling I closely looked at both PCB. Only the LCD module has some plated mounting holes, so I supposed that was the root cause of this issue.

My second AXE033 works perfectly with the same program.
I have an AXE033Y (the OLED version) which appears to be a very different board, at least judging by the pictures in the Rev-Ed store. Anyway, I buzzed it out, and the four mounting holes are isolated from everything, including each other. And yes, I powered the board up, and it works just fine.

I know this really doesn't answer your question, but it may give you hope that the board is suffering from something caused during the drilling, and not necessarily the removal of the plating in the mounting holes. A close inspection for cracked traces and the like may be in order.

For what it's worth, inspecting the edges of the AXE033Y board under the microscope hints that it may indeed be a 4 layer board, but I can't swear to that.
 

hippy

Technical Support
Staff member
The first line has every dots on and nothing on the second line. No more message is displayed.
That does sound like the LCD module not being initialised so, if it was working and another AXE033 does, it does sound like something has been damaged on that but hard to tell what.

I have filed out the mounting holes on some LCD module and not had any problem but it will perhaps depend on LCD model. I would tend to suspect a broken solder joint between the display board and the control board.
 

Technoman

Senior Member
The problem comes from the LCD module.

I thought having found the root cause in a previously repaired broken pin (DB0) with a solder joint, but that was not.

Interestingly, while I was swapping the LCD module and the controller board, by inadvertence I made a solder bridge between two data pins on the working LCD module and got the same symptom.

I'll have to look closely at the faulty LCD module for a short circuit.
 

nick12ab

Senior Member
The problem comes from the LCD module.
Not necessarily. As already stated, your symptoms are that of an uninitialised LCD, however anything can cause this ranging from ESD damage to a track being severed. I recommend using a socket (cut down from 20 to 16 pins) for the LCD display on all serial display products so that the display can easily be changed or tested separately.

For what it's worth, inspecting the edges of the AXE033Y board under the microscope hints that it may indeed be a 4 layer board, but I can't swear to that.
Everything on the AXE033 PCB has traces running on the surface of the board, so the board is unlikely to be 4 layer. The board appears to have layers from the edge because of the results of the V-grooving process on the FR4 fibres.
 
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