While doing some work to my 140B recently, it was necessary to remove the slide-in connectors along one edge of the A602 board (to enable it to be lifted up a bit). It had been apart for a couple of weeks and, yesterday, I went to reconnect the wires.
The wires are color-coded and the color codes are labeled on the board so it's not too difficult to tell which wire connectes where; however, when I had all the connectors installed, I noticed there was an empty slot on the board. I didn't recall that when I took it apart but I might have overlooked that (or forgot it in the interim).
Anyway, after searching for the "missing" wire, I finally concluded that a wire was not initially connected to that slot. The scope seems to work okay as-is so I think I was right; however, it does have me curious.
The empty slot is labeled "924" (white,red,yellow). Looking at the schematic, there are two 924 connections to that board; however, there are three 924 slots. The picture of that board in the manual clearly shows three slots as well.
After a bit of checking, I determined where the two 924 wires that do exist should go into which 924 slots. On further examination, I discovered that the empty 924 slot is connected (via trace on the underside of the board) to the adjacent 945 slot/wire.
BTW, 945 is the connection to the EXT/INT Z AXIS INPUT switch. One of the 924 wires is the UNBLANKING signal from one of the plugins and the other 924 connects to one of the transformer secondaries on the HV board.
Anyone know why there'd be an extra 924 slot that's connected to the 945 slot that way? I thought it might be for a test configuration or an option but don't know. Just curious...
Thanks,
Barry - N4BUQ
