Devo 7e power on issue

I was wondering if anybody could please chime in. I installed v5 and installed the nRF24L01 chip and it seems to work fine.

What I've been noticing is sometimes the devo 7e fails to turn on, or more specifically, if I quickly power cycle, ie: turn off and turn on it does not start. Screen is off. Nothing. But if I turn off and wait a few seconds, and then turn on, it's fine. Is this normal behaviour after installing a chip? Or is something wrong here?

My solder job looks decent, at least to me, and I don't think I burnt anything.

imgur.com/a/EUkBo

Thoughts

First try to solder a resitor (20-22K) between VCC and CE (pin2 and pin3), no direct shorting these pins. This may help.
Without this resistor, my screen was sometimes messed up after boot..

aMax wrote: First try to solder a resitor (20-22K) between VCC and CE (pin2 and pin3), no direct shorting these pins. This may help.
Without this resistor, my screen was sometimes messed up after boot..

Just to clarify, pins 2 (3.3V) & 3 (CE) on the nRF24L01 chip? I neglected to mention that I did short pins 2 & 3 on the chip instead of connected CE to VCC on the CYRF.

On the NRF pcb.

aMax wrote: On the NRF pcb.

Ok thanks. So you suggest to do both? Remove shorting of pins 2 & 3 and also add resistor?

Resistor only, works as a pullup. ( and current limiter).

Edit: ... any reason you did not use GND from the HF part (CYRF) but soldered it to the main pcb?

aMax wrote: Resistor only, works as a pullup. ( and current limiter).

Edit: ... any reason you did not use GND from the HF part (CYRF) but soldered it to the main pcb?

Ok, I'll try the resistor on the nrf pcb and keep the short.

As for the GND, I figured one less wire on the CYRF so when it comes time to add the CC2500, I'd connect its ground there. But I admit, I generally don't know what I'm doing.

When I first added my NRF my 7e did this. I later added an A7105 and also changed the ground to pin 7 on the CYRF. It has worked correctly ever since.

Deal57 wrote: When I first added my NRF my 7e did this. I later added an A7105 and also changed the ground to pin 7 on the CYRF. It has worked correctly ever since.

Thanks, that's good to know. Perhaps I'll wait for the cc2500 to arrive and do the same with the ground pin.

joelones wrote:
Ok, I'll try the resistor on the nrf pcb and keep the short.

.

This does not make any sense.
Ohms law...parallel.resistance will stay at 0 Ohm
The currend will flow through the short (0 Ohm) as if the resistor would not be present.