| Electronics > Repair |
| HP 34401a DMM with leaking segments |
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| qu1ck:
HighVoltage I'm going to find that out tomorrow when I take the multimeter apart again to do the fitting of the display and mcu board. From what I remember when I disassembled front panel earlier that window is just light blue acrylic (or some kind of plastic) and it should just tint my display in light blue but that's it. |
| bitseeker:
--- Quote from: qu1ck on July 07, 2018, 08:04:20 am ---Wrote bmp file to binary convertor and now we have proper icon support. See debug image below with all annunciators lit (diode and continuity are icons). --- End quote --- Excellent work. I really like how this turned out. Yours is the first successful matrix screen (LCD or OLED) implementation I've seen. --- Quote ---Funny thing, MS paint is the only (free) program that still supports monochrome bmp that I could find. And it has a bug where you can't paint in white with pencil tool :D --- End quote --- You can make them with GIMP as well. In the current version, go to the Image menu, select Mode, then Indexed. In the Indexed Color Conversion dialog, select "Use black and white (1-bit) palette." When you're done, export the image in Windows BMP format (saving, on the other hand, uses GIMP's native format). |
| qu1ck:
bitseeker Thanks for the tip, I found a plugin for paint.net can do it too so I'm using it now. GIMP's ux makes my skin crawl. I took the multimeter apart and did a whole lot of measurements. TLDR is I'll have to do a custom board. All measurements in mm Viewport dimensions (cutout in front panel plastic): 143.5x27 Useable width of the viewport (metal chassis takes away few mm on the left) ~137mm OLED display board dimensions: 100.5x33.5 Blue Pill mcu board dimensions (without jtag header, board only): 53x23 In terms of height everything fits fine, the original display has a metal shroud that is 35mm, new display board will fit there easily. Depth is tight but should be ok too. Old display has distance board to top of glass of 13.3mm but it sits in a little recess in the viewport. New display doesn't fit in that recess so I have to fit into 11.5mm of depth. And there is that fat DIP42 UPD7527 that takes 4-4.2mm of space under display. So there is ~7.3 left. New display is 6.5mm deep, including components on back side. Problem is width. As you can see 53 + 100.5 > 137 by quite a bit. You can win 6-8mm by moving display to the right so that the board edge and part of display bezel edge is not in the viewport but it is still not enough. If you overlap left part of display board with mcu board and chop off the jtag header part completely (may have to sacrifice LEDs too) then maaaybe it will fit. But that is too barbaric for my taste. So next thing i'll focus on is designing custom board. It's a shame, many people are afraid of soldering 0.5mm pitch qfps so it will limit this mod's accessibility for a hobbyist. I just hope that the kind of people that have this type of instrument are advanced enough in the soldering department that it won't be much of a deterrent. With custom board I will be able to stick the USB out through a small cutout in the front window panel. That will make firmware updates so much easier. And no, arduino pro mini while being smaller doesn't have the speed. 8bit AVRs suck these days, their only upside is availability in easily soldered packages. On the bright side, the display is quite, well, bright :D even behind the original tinted window. It doesnt even tint it blue, just decreases the contrast a bit. Without the window both displays have approximately the same contrast and brightness. |
| HighVoltage:
It looks very nice readable behind the original window. Very nice job! |
| bitseeker:
--- Quote from: qu1ck on July 08, 2018, 05:40:00 am ---bitseeker Thanks for the tip, I found a plugin for paint.net can do it too so I'm using it now. GIMP's ux makes my skin crawl. --- End quote --- Yep, always good to have options. --- Quote ---I took the multimeter apart and did a whole lot of measurements. TLDR is I'll have to do a custom board. --- End quote --- I kind of figured that might happen. However, you can then get things just the way you want them. --- Quote ---So next thing i'll focus on is designing custom board. It's a shame, many people are afraid of soldering 0.5mm pitch qfps so it will limit this mod's accessibility for a hobbyist. I just hope that the kind of people that have this type of instrument are advanced enough in the soldering department that it won't be much of a deterrent. --- End quote --- Hopefully, they didn't blow their budget getting the 34401A and can get a hot air station, if they don't already have one. --- Quote ---On the bright side, the display is quite, well, bright :D even behind the original tinted window. It doesnt even tint it blue, just decreases the contrast a bit. Without the window both displays have approximately the same contrast and brightness. --- End quote --- That's good news. I was afraid that the filter would be too dark. It looks fine. |
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