Paul Frere
TVWBB Member
Difficulties with Bryan's 4.3 Case/How to Fix
This post is intended to be informative for someone building an HM and planning to use the Kole 4.3 case with the four button holes. It is not intended to be critical. FWIW I worked my way through HS and college as an electronic tech before I got my MSEE. I also have a pretty complete shop, including a 3-axis DRO precision German mill, which was handy on this effort.
What I found is that the case is quite fussy about the soldered-together LCD and Button boards. There is a shallow cavity that locates the LCD and then four cavities that locate the switches. In addition there is a "fence" that locates the top of the LCD board in the case. I built my HM prior to buying the case so my LCD and button boards were already soldered together when I tried to insert them. To my eyeball, they were square, parallel, etc. Fitting this asembly to the case was by far the most difficult part of the HM build.
When the assembly was inserted, it would not come even close to sitting properly with the board against the fence, LCD in its cavity, and the switches in their cavities. First step was to file the top edge of the board at 45deg so it would slip farther under the fence and get the lcd properly aligned with its cavity. At that point with the LCD seated, the four switches were not centered in their openings. The buttons were toward the bottom of the opening and were shifted to the right as viewed from the front. I couldn't see inside, of course, but from the height of the buttons it was clear that they were not dropped into their cavities. Long story short, the switch board was immovably soldered to the LCD board, so when the LCD was properly in its cavity, the switches simply could not be in theirs. The consequence of this was that the whole HM assembly sat "high" in the case. The most obvious consequence of this was that the four probe jacks sat maybe 0.050" above the bottom of their cutouts.
After quite a bit of study, I ended up enlarging the switch cavities so that the switches would sit lower, then I milled 0.030" off of each of the main HM board pin headers, allowing the main board to sit closer to the button board and the probe jacks to sit closer to the bottom of their holes.
OK, finally, the point of the post: If I were to do this again, I would use the case as a jig for soldering the LCD to the button board. I'd make sure the LCD fit its cavity properly, filing the top board edge if necessary, then I would take it out, fit the button board, then reinsert the LCD board properly engaged with the button board pins. I would clamp the two board as necessary to make sure they were positioned correctly and stayed put. Only then would I solder the boards together.
Edit: Actually, as I think about it, I would probably also use the case as a locating jig for soldering the switches to the button board. IIRC there wasn't a lot of slop when doing this freehand but using a jig wouldn't hurt.
Hopefully this will help someone.
This post is intended to be informative for someone building an HM and planning to use the Kole 4.3 case with the four button holes. It is not intended to be critical. FWIW I worked my way through HS and college as an electronic tech before I got my MSEE. I also have a pretty complete shop, including a 3-axis DRO precision German mill, which was handy on this effort.
What I found is that the case is quite fussy about the soldered-together LCD and Button boards. There is a shallow cavity that locates the LCD and then four cavities that locate the switches. In addition there is a "fence" that locates the top of the LCD board in the case. I built my HM prior to buying the case so my LCD and button boards were already soldered together when I tried to insert them. To my eyeball, they were square, parallel, etc. Fitting this asembly to the case was by far the most difficult part of the HM build.
When the assembly was inserted, it would not come even close to sitting properly with the board against the fence, LCD in its cavity, and the switches in their cavities. First step was to file the top edge of the board at 45deg so it would slip farther under the fence and get the lcd properly aligned with its cavity. At that point with the LCD seated, the four switches were not centered in their openings. The buttons were toward the bottom of the opening and were shifted to the right as viewed from the front. I couldn't see inside, of course, but from the height of the buttons it was clear that they were not dropped into their cavities. Long story short, the switch board was immovably soldered to the LCD board, so when the LCD was properly in its cavity, the switches simply could not be in theirs. The consequence of this was that the whole HM assembly sat "high" in the case. The most obvious consequence of this was that the four probe jacks sat maybe 0.050" above the bottom of their cutouts.
After quite a bit of study, I ended up enlarging the switch cavities so that the switches would sit lower, then I milled 0.030" off of each of the main HM board pin headers, allowing the main board to sit closer to the button board and the probe jacks to sit closer to the bottom of their holes.
OK, finally, the point of the post: If I were to do this again, I would use the case as a jig for soldering the LCD to the button board. I'd make sure the LCD fit its cavity properly, filing the top board edge if necessary, then I would take it out, fit the button board, then reinsert the LCD board properly engaged with the button board pins. I would clamp the two board as necessary to make sure they were positioned correctly and stayed put. Only then would I solder the boards together.
Edit: Actually, as I think about it, I would probably also use the case as a locating jig for soldering the switches to the button board. IIRC there wasn't a lot of slop when doing this freehand but using a jig wouldn't hurt.
Hopefully this will help someone.
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