[volt-nuts] Replace neons with LEDs in Fluke 845AB

[Dallas Smith]

Hi Lou,

Its been awhile since I made this mod, but I had the foresight to save 
the project to K04BB's site.

K04BB /Fluke/Fluke 845A AB 
<http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=Fluke/Fluke_845A_AB>

Still works great, hope you have the same results.

Dallas



On 6/5/2016 9:51 PM, Lou Amadio wrote:
> Question for Dallas Smith:
>
> I want to replace neons with LEDs in my Fluke 845AB.
>
> Following your instructions below, did you mount the LEDs where the neons
> were on the PCB and use the plastic light tubes or did you mount the LEDs
> hard up against the LDRs in the yellow foam block?
>
> Thanks, Lou
>
>
>
> Quote
>
> Dallas Smith, 2 years ago
>
> Permalink <http://narkive.com/bdOZWNXt.1>
>
> Raw Message
>
> Report
>
> “Finally got around to modify my Fluke 845ab with LED 's for the chopper
> circuit. Used the 17 volt windings for LED's (Mouser
> 941-C513AMSNCW0Y0511 Warm White Round LED) instead of the 130 volt, move
> red wire on transformer pin 9 to pin 7.This winding is 180 degrees out
> of phase, so I reversed the steering diodes (CR106 & CR107) I left in to
> help make sure the phase was correct for the LED's when connecting.
> Change R154 to 6K to set the brightness, selected for good operation of
> the zero control. Then install jumper to replace C119. Also changed the
> filter integration response caps C111 to .022uF and C116 to 47uF, this
> stabilized the jitter to a manageable mode of operation. Meter now works
> as well or better when the original neon's worked.”
>
> Lamp Blocks
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