[GreggWardNZ]

Is the switching-mode converter of known "good design" (or ebay no-name Chinese) and is the replacement the same model?

Cheers, Alan.

Hi Alan, the power supply is a Chinese made Soanar that is meant to be good for Arduino projects. The replacement is completely different to the original.

[GreggWardNZ]

Today I checked the connections on the 7809 regulator. There was 12V input and 8.94V output. Most of the 5V connections on the board showed 5.01V.

Another thing that I noticed whilst testing the Rx board, was that if the board only had the USB connection or the power connection plugged in, not both, then the Rx unit seemed to be receiving the data from the Tx unit. When both the USB and power connection were plugged in, the Rx seemed to lose connection with the Tx unit.

I thought maybe some of the solder connections to the Nano were maybe a little light on solder, so re-soldered all of the Nano connections. After that I restarted the Rx board and it seemed to work perfectly for about 20 minutes with both the USB and power connections plugged in. After the 20 minutes, the Rx board stopped responding again, both as far as the Tx LED flashing and connection to Cumulus goes. I ended up removing the power connection, restarting Cumulus and everything went back to working on the USB connection.

[AllyCat]

Hi,

If the dc supply voltage (particularly on the receiver module and nano) is the same under all 3 conditions (Main Power supply, USB and both) then I'd still be looking for RFI. Maybe the PSU and USB are "fighting" each other, or maybe one cable is acting as an "antenna" (a known issue with some of the Fine Offset Consoles).

Can you try a different USB supply: Perhaps a separate "mains adapter/charger", or another PC? The nominal USB power supply voltage is 5 volts, often it's higher (around 5.5 v) but it might be as low as 4.5 volts.

Cheers, Alan.

[werk_ag]

I have been using several types of power supplies, inclusive cheap chinese ones, and I never seen this behaviour. As AllyCat said, maybe you are facing a strange RFI problem.

Having the two PSU and USB power "fighting" each other, not seems to be the problem.

The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source.

"The board has a simple two resistor voltage divider wired to the Vin voltage, if there is a voltage of sufficient voltage, a op-amp comparator circuit switches off a MOSFET switch that then isolates the USB voltage from the board's Vcc bus. So if there is both USB voltage and Vin voltage available, then the Vin voltage takes priority and is used to power the board. "

When powered by the external 12V power supply, the 9V from the 7809 regulator is applied to Vin (pin 30), so as this voltage is greater than the USB power voltage, its automatically selected to feed the Arduino.

Just for testing, try AllyCat sugestions:
Try a separate "mains adapter/charger", or another PC, is possible try also a shielded USB cable with ferrites.

[GreggWardNZ]

Thanks guys, I will try your suggestions and get back to you.

[Palmyweather]

Just wondering, was the Arduino Nano soldered directly onto the circuit board, or was an IC holder used first with the Arduino Nano mounted afterwards?

If soldered directly onto the circuit board, could excess heat maybe have damaged some of the sensitive components on the Arduino Nano resulting in this kind of issue? Especially with this explanation below:

The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source.

"The board has a simple two resistor voltage divider wired to the Vin voltage, if there is a voltage of sufficient voltage, a op-amp comparator circuit switches off a MOSFET switch that then isolates the USB voltage from the board's Vcc bus. So if there is both USB voltage and Vin voltage available, then the Vin voltage takes priority and is used to power the board. "

[GreggWardNZ]

Just wondering, was the Arduino Nano soldered directly onto the circuit board, or was an IC holder used first with the Arduino Nano mounted afterwards?

If soldered directly onto the circuit board, could excess heat maybe have damaged some of the sensitive components on the Arduino Nano resulting in this kind of issue?

I made up a socket connection for the Nano, using female header connectors and have always removed the Nano when soldering/re-soldering.

Today I bought a shielded USB cable that advertises that it protects against potential electromagnetic interference, but that made no difference to the problem. After connecting up a USB mains adapter/charger, the Rx board appeared to start working properly. However, after about 5min I swapped the USB cable back into the PC and it continued to work, so I don't really know whether that actually proves anything.

I'm starting to wonder whether the DCCduino Nano (cheap clone) on the Rx board may be faulty. Maybe it could be faulty around the switching circuitry that Werk_AG outlined. I am just in the process of purchasing a genuine Arduino Nano, to see if that will make a difference.

[werk_ag]

"The board has a simple two resistor voltage divider wired to the Vin voltage, if there is a voltage of sufficient voltage, a op-amp comparator circuit switches off a MOSFET switch that then isolates the USB voltage from the board's Vcc bus. So if there is both USB voltage and Vin voltage available, then the Vin voltage takes priority and is used to power the board. "

One correction: The above applies only to UNO, the Nano does the same function in a more simple way, it uses only a diode!

Just wondering, was the Arduino Nano soldered directly onto the circuit board, or was an IC holder used first with the Arduino Nano mounted afterwards?

If soldered directly onto the circuit board, could excess heat maybe have damaged some of the sensitive components on the Arduino Nano resulting in this kind of issue?

Regarding this concern: Sometimes I mount the nano with sockets, others I solder it directly on the board, but when I choose to solder it on the board, I use the full pin length, to keep it raised relatively to the RX board, this allows a better air flow (the nano voltage regulator is assembled in the underside of the Nano board)

[werk_ag]

I'm starting to wonder whether the DCCduino Nano (cheap clone) on the Rx board may be faulty. Maybe it could be faulty around the switching circuitry that Werk_AG outlined. I am just in the process of purchasing a genuine Arduino Nano, to see if that will make a difference.

GreggWardNZ, I never used a DCDuino Nano version, but I always used cheap chinese Nano clones, and generally they work well.

If you gonna try with another arduino, try a different model of the DCDuino. These are really good (Can't assure the FTDI chip is original, but vendors claims it is)





What I like more is these models are the voltage regulator, seems more capable for high currents than the AMS1117 installed on other Nano's. The N00A regulator is a LM340 in a SOT-233 package

[GreggWardNZ]

Thanks Werk_AG, unfortunately I have already ordered a Gravitech one from a local supplier. However, I want to add another Tx unit and a WD unit, so I am going to order a couple of the Nanos that you suggested. I went to the geeetech.com site and am going to order the Iduino Nano V3 ATMEGA328 boards.