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| Fluke 8600A Battery / Power Supply Conversion |
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| Seekonk:
Good refurb. I think you made the best decision. I thought about the many ways to convert this Li batteries if it were mine since I have stacks of used batteries. This is a good bench meter, but too clunky these days to take out in the field. |
| xrunner:
--- Quote from: SeanB on March 15, 2015, 05:37:16 pm ---Add the optional MOV to that little board, it will help it last longer. --- End quote --- OK good idea. --- Quote from: Seekonk on March 15, 2015, 05:41:36 pm ---Good refurb. I think you made the best decision. I thought about the many ways to convert this Li batteries if it were mine since I have stacks of used batteries. This is a good bench meter, but too clunky these days to take out in the field. --- End quote --- Thanks, yea these days who would drag that into the field with batteries - the thing was pretty heavy with all those D cell NiCads. But it's a really good bench meter so why not convert it? I was very surprised when I got this one because it's so clean. The inside looks like it just came off the factory floor. On the top back it has "USN" stenciled on it, but I would never have believed it was in the possession of the Navy. It's just not been abused at all. Well, except for the V-ohn and common jacks. The inside is so worn the banana plugs do not fit in at all tightly anymore. I'm going to change them out with new ones. Maybe it was in some lab for years and just sat on a bench, someone plugging and unplugging various things? :-// |
| Seekonk:
Since you have a stack of wall warts, it is easy to change the voltage up to several volts. That opto isolator likely has a zener in series in which case a diode or two in series will bump it up a little. OR they have a TL431 that gives you lots of options for voltage. Some here talk about crappy wall warts cause they draw half the rated current and the voltage drops. Look for a resistor on the output that is a current sense feeding a transistor to the opto. Remember, most of these are chargers and they limit the output in the case of dead or damaged batteries. I do a lot with solar and many of these modules will work down to 50V at reduced current. Nice for an isolated high side driver or operating a micro. |
| xrunner:
So here is the final installation. I kept all the holder parts for the NiCads, and used one of them to hold the PS board off the circuit board I also needed to replace the banana jacks on the fromt due to extreme wear, so I disassembled the instrument and pulled the front panel so I can replace the jacks and re-work the wiring to them. |
| PlaneSailing:
Case temperature after Fluke 8600A line only conversion ? Was given a non working Fluke 8600A with the battery option, and I converted it to line only. Took out the NiCads and plastic holder pieces, and saw much corrosion of the PCB traces. 2200uF 25V and an LM7805 in their "line option" PCB locations of C103 & U102, custom heat sink of bent aluminum, a few cut traces & jumpers, and it now works well. The display was also "loopy" till re-soldered the connections from the flexible display PCB to the mother board. Had to remove the yellow wire from the center tap of the transformer primary side, and also CR22 (mislabeled as CR21 on schematic) & CR 23 to fully remove the line voltage from the transformer when turned off. A 0.1uF on the output of the LM7805 to try to remove the 50mV pk-pk 10kHz regulator switching noise resulted in oscillation of the new 5V regulator (against the L2 coil maybe ?). Otherwise all well, so just did not use a 0.1uF. It's a cute little 4.5 digit meter - not as good as my HP 3466A, or as much character as my Solartron 7045... but really nice. Question : Can someone with a "natural" line only 8600A, or the battery option version, tell me if the outside top of the plastic case over the transformer gets warm ?. Mine does, a noticeable 120 degF (measured with IR thermometer) after 30 minutes at the hottest spot on the center back top of the case. I "think" it's the transformer. If it's not supposed to be that warm, plan to drill a few 1/4" holes in the back of the case, thanks. |
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