Mana SE modifications

[rpt007]

I know, that this topic is not new, but I thought I could give new users a short and comprehensive idea how to modify their Mana SE boards in order to
install some remedies to the problems when the Arduino Nano's pins are temporarily floating (e.g. when switching between T2Laser's two application panes), so

1. solve the LaserON problem (10k resistor between GND and S-pin)
2. solve the hissing of the motors (they get shortly enabled = get current flowing through their windings, luckily without getting DIR & STEP pulses) by a 10k resistor between +5V and D8).

I also hotglued and soldered male connectors to the board to wire 3pin homing switches (the ones which come with the LEDs), so that they are connected to +5V, GND and D9 of the Nano. You could also just use GND and D9 when using switches not soldered on the board with an LED. In the case that you are using these LED equipped switches +5V is needed and then you MUST REMOVE the NC-pin of the switch!! see: http://benboxlaser.us/index.php/topic,1494.msg21588.html#msg21588, reply #77.

In the first pictures you see the modified homing switches which I use and a blue LED with a 1k resistor in series, plugged into the motor output connector. This allows me a very safe testing instead of having the laser connected all time.

[UHF]

Thanks for this. The Laser ON problem is when it decides to switch on fully for several seconds when connecting/disconnecting/updating firmware/looking at it/thinking about/etc...? The 10K pull-down resistor will solve this?

This guy has some great modifications, among his entertaining videos: https://www.youtube.com/watch?v=ZzO9skEYqwY

[ggallant571]

I think the 10K is a little weak. Especially for cables over 25cm. I started with 10K and switched to 4.7K. Others have used 1K.

[Zax]

I prefer to put the resistor on the laser module, since it's a design flaw with the driver not the Mana SE. It is safer as if you are unlucky and the TTL wire breaks the laser will go off instead of full on.

[rpt007]

My current laser is a 1600mW type with no electronics easily accessible. So I chose the mod on the SE board. I ordered another laser with 2500mW. Here I can make the mod directly on the attached electronics board. Again I will start with a 10k value and will test it with another non modded driver board which I have in stock.

If it works for me I will stay with that value as it doesn‘t draw much current from the Nano. Using this modded new laser module with the modded SE board will result to ca. 5k, which is still ok as it draws around 1mA from the Nano.

@ggallant571: you are right, the longer the cable the lower the value as the cable adds a capacity which might collide with the timing of the laser causing delays and at higher speed could dillute the burning pattern.

[Romoshka]

I think the 10K is a little weak. Especially for cables over 25cm. I started with 10K and switched to 4.7K. Others have used 1K.

Before diving into this laser thing the last time I dealt with electronics was in High School (45 years ago) So either my recall is flawed or your advertised sarcasm was employed.  "10K is weak so I went to 4.7K".  Since you told me recently that you were the worlds foremost authority on resistors I'm asking for explanation/education.

[Zax]

The lower resistance = higher current flow, so depending on the application and in this case it is correct to say the 4.7k is stronger than the 10k, and a 2.2 or 1k would be even "stronger".