I haven't messaged the AliExpress seller about the controller board yet, I'll do that in the near future. But I've had bad luck in the last week or two, when it comes to communicating with sellers and getting back good answers to questions. I think the language barrier is the biggest thing. And without pics, it's hard to know what you are getting. Or you could order the same thing twice and get two different things.
I've been looking at the idea of modding one of the other two boards (green or blue), because these are the boards that KSGER official store sells and I'm hoping they would still be available later in the future. Between the two, I've been favouring the green board, despite how crude the design is, there are some advantages.
With the GX12 connectors, I've had a hard time finding a high quality version. They all seem to be cheap Chinese ones. And they can't be desoldered without damaging the connector. So it seems easier to chassis mount the connector and have a bunch of spare connectors in a draw somewhere. Also, the KSGER design puts the connector lower than the center line and this makes it incompatible with other front panels. Chassis mounting the connector would mean that it is floating and could be used with other front panels. There is an option to cut the blue PCB and do the same thing. On the blue board, the thermal resistance varies between 46C and 90C depending on the board it's mounted to. The blue PCB is a more dense board and the pins of the regulator are reversed. The pin orientation makes it hard to plan a mod in advance because some of the components are on the other side of the board, where the display is. It's hard to know if there would be access or not.
The green board is crude and basic, but it makes it easier to mod. At first, I looked at replacing the regulator but didn't have any luck finding anything better than what is in there. On the datasheet the thermal resistance is 62C. Other alternatives, were cheaper but the thermal resistance was only 50C. So it seems better to keep the SPX2954A in there.
I've explored the idea of using a 2W Metal Oxide resistor to lower the input voltage. I did some simple diagrams at first, but realized the scale was way off. These boards and all of the components are really small. I looked at some datasheets and tried to get a better idea of the scale, and tried to draw it closer to real scale. I attached a diagram with two options, with resistor before or after the cap. The resistor could be soldered to the input pin of the SPX2954A, or from the empty pad/trace from C2. I generally like to favour strong mechanical connections, but also.. I'm worried that soldering directly to the regulator could damage it. So maybe laying the lead wire flat and soldering to the pad would be less risk.
The diagram positioning isn't literal, it's more to make it easier to read with the labels. For example, the positioning of the cap or resistor could be re-orientated to make it fit better. The components could float in the air 1cm away from the PCB, or be quite close, depending on internal space available. I found some super small heatsinks locally.. 4.5x6mm and a 6.5x6.5mm. The SPX2954A is 6.5mm wide. It could be an option to further reduce temperatures if the resistor alone isn't enough. I don't even know how much heat such a small piece of metal would dissipate, but the heatsink could be attached with a mixture of CPU thermal compound and thermal glue. I've done this before and it works ok.
The mod would have to be right first time because apparently these PCB's are so cheap, they can't handle being desoldered and resoldered much. The thermal glue would also be permanent, but those boards are pretty cheap, so it's easy to have a spare lying around.
I can't find the capacitance value of C2. Would it be better measure it and then order the same value, or is there a value that could be suggested that would work well with this 2W 120R resistor? Would 3W 150R or 200R be better?
My main question is if I am understanding the problem properly, and secondly would this solution work if these components can fit? And is it better to have the cap after the resistor? It usually looks that way in schematics. What uF range would be good for the cap?