I'm sure there's a dry solder joint somewhere on my display board, or perhaps a broken trace, but I'm having trouble finding it.

My symptoms are as follows:

- Sometimes the button lights will be on, sometimes they will be off.

- Putting pressure on the face makes the button lights blink on and off. Interestingly, it's just about anywhere on the face. At either end, in the middle, whatever.

- Sometimes the knob LEDs will be on, but the button LEDs will be off. This I find odd, because the knob LEDs get their on/off signal indicator from one of the legs of the button LEDs. So I guess that means the button LEDs aren't getting enough juice to light up, but they are getting enough juice so that the signal to activate the knob LEDs is working.

- When the button LEDs are malfunctioning, if I go into the dimmer menu on the player, it does not affect the brightness of the VFD display. Only after I press on the face to make the buttons light up, does the dimmer menu actually cause the display to change brightness.

I've tried to hit various solder joints on the display board with a soldering iron, places like surface-mount chips that looked like they were kind of dry. But the problem came back the next day.

I've checked and resoldered all of button LED connections, and the resistor pack. They all seem to be operating at spec. My hunch is that the problem is upstream of the resistor pack.

Any ideas where the dry solder joint or broken trace might be? Note: difficulty level= This is not a standard Mk2/2a display board, it was one of their early beta boards from back stock when they swapped me for a display that had the half-missing-picture problem. I have noticed its physical layout is different from the production boards, but most of the components are more or less the same.

Hmm... That last comment about the dimmer setting (I assume you mean the standard dimmer, not the LED brightness) is rather curious. This implies (to me) that the fault is also causing problems with the standard VFD. Look along the power lines feeding the resistor pack.

Either that, or the fault may be with the display board itself, and not the LED circuitry. If there were a bad capacitor (or other component) you would see symptoms in the LEDs and VFD, but they would not be the cause.

In any case, I strongly suspect a power lead. On Brian's original button page, the knob is connected to the +5 of the IR board and ground near the knob. Different power leads... And your symptoms seem to support this.

Yeah, it's difficult to trace where the power lead goes, the one upstream of the resistor pack. It's a 4-layer PCB and the trace disappears into it... I'll try a bit harder...

Also, I forgot to say that another thing which indicates a problem with the button LED power supply trace is: When they fail, all four buttons fail equally. Sometimes as they flicker on and off, they are dim, and in that case they are all equally dim.

Player dismantled, soldering iron heated, multimeter in hand... wish me luck...

I've traced where both the grounds for and the power supply for the button LEDs goes. Both sets of connections go to a bunch of different places on the board, and I can't find anything wrong at any of those places. The power seems to come from one of the pins on the display cable, but that pin, the display cable, and the pins on the motherboard all seem fine. Stumped...

Hm. After dismantling, and heating almost every solder point on the display board and even the solder points on the display-cable header on the mainboard, then reassembling, it seems to be working correclty. Of course, that's the same thing that happened the last time I did this... it worked for a day and then started to fail again.... We'll see if this holds up...