Since I don’t really know what is going on, I decided to look at the Deck Legend official schematic again.
http://www.deckkeyboards.com/support/deck-legend-schematicOh my gosh, I didn't even know this existed> Yet another reason why TG3 is so awesome!
Looking through it now.
It gives me the impression that Column 18 runs thus: * - 9 + Enter Del.
And that the rows are wired like this:
Pause *
/ -
8 9
6 +
3 Enter
0 Del
You can see the entire matrix in this image (from the manual, first page).
so
/- are in row2
8 9 row 3
6+ row4
3 enter row5
0 del row6
It has a very compact matrix, with only a few unused locations.
Would it be correct to say that every key in column 18 should have continuity with Pin37 because column 18 eventually leads to that pin on the master control unit?
No, and for a few reasons.
First of all, every key has two pins on it. one of those pins connects to the columns via a diode. The other connects to the rows (no diode). This means that one pin of all the switches in a row are all connected and you can trace that connection all the way to the controller. For the colums, one side of the diode is conencted all the way to the controller, and one pin on each switch is connected through the diode to the controller, so that each switch has only one diode between it and the controller. You can verify this by putting your DMM in diodes mode and putting one lead on the correct pin on the controller, and the other on the proper side of the switch (or either side of the switch if it is pressed). You will get a Vf of ~.5V showing that there is one diode.
You can also verify this by looking at the schematic on pgs 2&3. You can see a clearer example of this by looking at backspace and = on the top right of page2. There is the switch pin, then a diode, then a common line running to col13 directly to the controller. Notice they are in different rows.
Deck’s schematics mention column 18 being led through RN3.C (resistor RN3.C?) but I don’t see any such resistor labeled on the PCB.
I also found no continuity between any member of column 18 with each other. However, I also tried the members of column 17, and there is no continuity between their members either, so I don’t know how it works.
THose are part of a resistor network (labelled RN on the PCB) you can see those as just a row of resistors soldered and labelled RN1 RN2 and RN3 in your pictures in the post above.
Pin # 37 is for col. 18, so there is a break somewhere between the controller pin and the switches. It could be the solder point grendel mentioned, or somewhere on the PCB (requires desoldering the entire thing) or somewhere on the controller daughterboard
If its the first one, you can likely fix with a jumper wire without desodlering. If it's the second, you will have to do more drastic measures (desodler that daughterboard and repair trace or reflow pin there?) Hard to say.
With your DMM in continuity mode, is there continuity between the pin#37 and the other end of the diode (square pad) near switch. If you try this on working rows you should hear a beep, and can use this to recognizer which diode is paired with what switch (they are mixed around a little to make room for holes in the PCB and other features). On troublesome column 18 this may or may not be the case, but might help isolating the issue.
Also note: you might have to press hard on the pad. Sometimes you have to pierce a thin oxidation layer before it will read continuity.
Another option is to put DMM in diodes mode and measure from the left pin (closest to center of switch) to the square pad to make sure the diode is measuring properly, then measure from left pin to pin37.
