Products > Test Equipment
Old Fluke Multimeters
drtaylor:
The 8060 LCD is fully duplex and almost all the pins serve two LCD segments. Any scheme to change the display to LEDs will require duplexing the LEDs as driven by the backplane pin.This apparently has been worked out before.
JdaleH:
drtaylor, thanks for joining the conversation. I have done a little research on duplexing LEDs and I see how it is done. I have asked Dmitri on mrmodemhead's blog to help out with the schematic he developed. By careful inspection of the disassembled display along with the schematic, I have mapped out most of the duplexing, but have a few connections to the backplane I haven't figured out for sure. Now that I know what I am looking for, I will go back to the display and look some more for the few connections I have missed.
The duplexing complicates the pcb design a bit, but still doable. I am going to leave it to the EEs to figure out how to keep from burning out the microprocessor. (anyone want to give it a go?) Dmetri used green low current LED with 12k resistors. Maybe someone will back calculate what LED specs will be suitable. Hint: Kingbright has some reverse insertion LEDs that install in holes in the pcb (to reduce overall thickness).
I think my part should be limited to designing the pcb (which is what I do the best). I really wouldn't want to lead the process of having a new run of custom LCDs made up through a group buy, but that is a real alternative as I have read that getting a custom LCD made is not outrageously expensive. If anyone wants to look into that alternative, have a go at it. Dale
ogdento:
JDale,
Dmitri sent me some scans of his paperwork about a year ago and I found a schematic I made from it. I just redid it in Kicad and posted it over on the OLED thread, which I guess is no longer about an OLED mod ;)
It sounds like you've got some pcb experience, so maybe we can put our heads together and make a couple of these... and if they work then anybody should be able to copy our design.
https://www.eevblog.com/forum/testgear/fluke-8060a-refurb-possible-mainboard-to-micro-hack-and-oled-conversion/msg2856550/#msg2856550
JdaleH:
Hi, I looked at your schematic on the OLED thread. I noticed that someone took exception to the layout. I haven't taken the time yet to look at it carefully because I think you will probably do that. I usually use ExpressPCB for laying out my pcbs because the interface is so easy to use. If I don't need something that fits their pcb size, I have a "secret" method to convert my work to gerbers for Chinese fab or OshPark. I usually am making up small boards for my use in other peoples projects that I want to build. Once you give me the green light that you are happy with your layout (and the orientation of each LED, please triple check), I will get started. I haven't looked up a particular LED to use, but I will try to use the same form factor that Dmetri used. I am thinking I will first layout the overlay needed in Coreldraw. Once I am happy with that, I will get the x-y location of each LED for transfer to the pcb. I will send you the overlay when finished. Thanks for you help. That schematic is awesome. Dale
ogdento:
Hey thanks JDale, I fixed the schematic but do need to verify signals etc. so I'm going to try and re-do my little test rig for that. I'll let you know when I get that figured out and have the layout fixed up. I've also got some dimensional sketches so I'll get them up there too.
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