Because i have had several motherboards for repair which in my case just works, but not by the owner I noticed that it is not always a fault on the motherboard, but most likely due the front panel. As far as I'm looking at, the motherboard dc/dc converters are switched on separately from the front panel. Most likely with a ic from the panel. By making a few bridges on the connector, they can be activated without the use of the front panel. Every connection is to switch on a dc to dc converter, missing one connection results of disabling one dc converter. For example you may have a red led issue and thinking that it's related to the software while it's actually caused due a issue with the front panel, or connection from it. Same as you may see in a rs232 terminal output screen with only a code 73460012 which I noticed it were related to a inactive 1.5v on the motherboard. When I used this jumper plug the motherboard just worked. In any case, this information may help you to find the problem but best is to first measure the main dc/dc converter outputs to see if there is something wrong with it. If so, then it may be handy to make this jumper connector to see if it's related to the front panel. However at this moment I do not know the push button pin, so it's not usable to flash the box by this way, thus for to do that you need to add a empty text file and named it force.update and to place by the other files in the solo2 map. By adding it the box it should directly do the usb update and when done reset the box after a time. But by not using the frontpanel, you need to use the rs232 serial connection to see when it's done, otherwise it keeps flashing the box. But maybe, if I have found it, I will add it to the picture. But it's for me hard to find at this moment due the leak of owning the solo2 front panel, I only have the motherboards.
I've made a drawing with the dc to dc ic's on/off switching overview. Could be handy if one or more of these ic's failed to operate. Also included the data sheets related to these ic's. Click on the picture for a full view.
Voltages and Ohm measurements from the front panel motherboard connector. Which could be handy if you have a issue and may be related to the front panel. Measurements done from 3 situations. 1. Ohms measurements, done without the front panel connected. 2. Vdc measurements green, done without the front panel connected, board inactive. 3. Vdc measurements orange, done with the jumper plug, board active. I'm not be able to do the measurements with a front panel connected because I don't have it. Anyways, here are the measurements I have done, done from two boards. Click on the picture if you like to see it fully.
Hello, I have a solo2 with vfd problems, sometimes the display goes off, but after most of the time the vfd does not light up, it stays off, I don't have any anomalies on the series, I changed all the capacitors, I checked the voltages on the cable and the 5 Uxxx as in the photo by you, without anomalies, I don't know where to control to make this display work. I mention the remote control works and the touch key works, everything works except this vfd thanks in advance. Add putty log files
Unfortunately I only had the solo2 motherboard and not the front panel. So, regarding the front panel itself, I have no information on how it is controlled. As a result, I can't give a direct answer where to look. But thinking about this, it could be a voltage problem, thinking about the vdc supply of the 12vdc. Another possibility is maybe a bad contact of the display flat cable, or a break. Or the display itself is running out of age. I think, check the front panel cable, check that all connections are making good contact with the connector. And if okay, check the voltages, whether they are present. And if also fine, check the front panel for bad outdated soldering.