forum.pistar.uk

Hi,
I have a MMDVM Jumbo Spot Rev 1.7 09/2018 mounted on a Pi Zero W. It works perfectly no problems. I purchased a second Pi Zero W and MMDVM identical to the first. The 2nd MMDVM will not work. Through a process of trial and error I have narrowed the problem down to the 2nd MMDVM board.
When I take my first board off the Pi (which works fine) and put the second board on (running the same SD card) the second board will not run. I can access Pi_Star with the local command fine, I can edit the software fine. Everything software wise appears to work perfectly. However the MMDVM board itself only has to lights PWR and SVC. The lights do not come on for any of the modes selected (DMR & YSF) on the Dashboard the Network Status indicators are green but above the Modes Enabled panel for both are red. Occasionally they will both flash green for two seconds than go back to red again. The hotspot will not send or receive. The OLED screen is not working either.

Anybody have a similar experience with a solution? Any Ideas?

John O'

At a guess the TCXO is either not running or the ADF7021 RF chip is not seeing the clock signal from it.

Suggest you open a new browser tab and look at the live log as the PiStar boots, if it successfully sees the modem firmware but then never does anything more it could be what I suggested. If it doesn't see the CPU and can't read the firmware version then it could be the 8MHz crystal oscillator not running or some sort of power problem feeding the modem board.

By substituting the MMDVM boards you have isolated the problem to the MMDVM board, return it for a replacement or a refund.

Is it a Chinese copy board from eBay? I have a Chinese eBay one, the seller(s) typically sell all sorts of non radio items and ship from a local shop/house. Almost all have a generic sticker with an offset of 500 and several have the wrong parts fitted in the antenna filter resulting in very little RF output. I had to work out the offset myself and had to remove the filter parts in order to obtain more than a few nano Watts (it was originally -35dBm max output). I doubt these boards are tested, other than perhaps to see if the LEDs work.

73 Dave

If you still have the new HS, you might want to try a different Freq. In MMDVM firmware 1.4.12, they made a change to keep HS's out
of the Satellite area of the band (435-438). I see the freq. you choose is right on the edge.

-Pete N2MCI

My apologies, I forgot to come back and state the fix to the problem.
one of the chips on the MMDVM board was fried. It turns out the pins on the MMDVM come into contact with the header pins on the Raspberry Pi when installed on the PI. The MMDVM board became junk.

Solution (before you install the MMDVM board) is to trim the pins all the way down on it to the solder joint so when the board is installed on the PI the pins will not come into contact with each other.

John O'