| Products > Test Equipment |
| Modding a Keithley 197 |
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| rwzahora:
My 197A had a very weak backlight so I thought I'd look into replacing it. The old panel was a Loctite LSI 37269-1 as shown in an earlier reply. It is 19mm x 86mm. I purchased a panel from eBay (https://www.ebay.com/itm/393103760354?var=662007375026) and cut it down on three sides and nail-polished the edges. It works and the light is much better than the original unit although I would have liked it even brighter. The voltage to the panel is 76Vac measured with a multimeter and the drive is triangleish at about 370 Hz. |
| jupiters_spot:
Reading through this thread it seems that: - the 197A has a backlight, and some here have needed to replace the inverter driver to supply the correct voltage to the electroluminescent backlight - there aren't any posts about adding a backlight to a 197 (as opposed to 197A) display. Did I miss such a post? Adding a backlight to a 197 appears to involve two primary steps: install appropriate inverter to drive EL strip, and trim/seal/install EL strip behind LCD display. All of the EL drive inverters I see either require 12V DC or 120V AC, and I'm not sure I see a convenient source of switched power of either sort in the base 197. I'd want the backlight to turn on/off with the meter's power button so I'd need to power the inverter somewhere after the meter's power switch. If anyone has installed an inverter and EL backlight in a base 197 (not the 197A), please share with us how you powered the EL drive inverter and where you managed to stuff the inverter into the meter's case. |
| tooki:
A 197 display upgrade has been a project on my to-do list for a few years. :p I don’t think there’s much sense in using EL these days, since LED is so much easier to drive. Long-term, an entire replacement display board, using a microcontroller to decode the original display signals and reformat them for some modern display, is likely a smarter way to go. (The work to decode the original display signals is already complete.) |
| jupiters_spot:
--- Quote ---Long-term, an entire replacement display board, using a microcontroller to decode the original display signals and reformat them for some modern display, is likely a smarter way to go. (The work to decode the original display signals is already complete.) --- End quote --- I'm intrigued. Looks like someone has done it: https://www.reddit.com/r/electronics/comments/pkknvk/keithley_197_with_oled_display_upgrade/ |
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