Hi there, it's now 2022 and I know this thread is somewhat old. I have owned my HD-500 for a number of years. Purchased used through Ebay. Never used it in a live setting but for recording only. I noticed the same issues many have reported on with the switches. Sometimes a few would engage or not. I've read and researched this over a variety of boards including this one. I've managed to fix my issues and wanted to share it. Before doing this job be sure to have a small socket wrench for the internal (3mm) nut which holds the Switch board to the Chassie. Also have 2 needle nose plyers +Philips screwdriver. Also have on hand some cleaner- degreaser such as DeoxIT (Not the spray but the needle applicator type.
- Remove all Phillips Screws on the botton with the exception being the two middle screws. These attach to the metal providing bracing for the floorboard.
- Slightly move the bottom to left or right then pull the bottom out. Leave the unit upside down for the remaining procedures.
- Remove both Nuts from each side of the switch boards. Do the same for the next set of switches
- Carefully use a screwdriver and lightly pull back the brace lock at the back of the switch board for each switch, then pry back the additional locking pieces. lightly pull
up each switch section until all are removed then flip just the switch board piece upside down so the springs do not fall out from each of the metal switches above
- Apply a few drops of the cleaner degreaser and lighty depress each switch on the circuit board then lightly wipe off excess.
- Using needle nose plyers, carefully pull spring with plastic off. Remove plastic depression button temporarily and hold spring with two needlenose plyers securely through the end of the rings and lightly pull them apart a bit to stretch the spring. Put plastic piece back on and back into the metal piece of the upper button mechanism. Do this for all remaining switches.
- Re-assemble unit and put the screws back on.
- Power up the HD-500 and test. You should notice a large improvement for engaging the switches.
This procedure fixed all my floorboard button issues.
- Best - David
