Electronics > Repair
Fluke 343A repair
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Rax:

--- Quote from: daisizhou on June 25, 2024, 07:12:51 am ---You choose to replace the original capacitor with a smaller capacitor.
Although their capacitance and withstand voltage meet the requirements, large capacitors have high power, while small capacitors usually have low power.
In other words, the redundancy performance has become weaker

--- End quote ---

If you mean smaller physically, things are nowhere near that simple. Manufacturing of electrolytics capacitors has come a very long way since the late '60s, and using 105C 5k+ hrs life capacitors of equal or higher capacitance and voltage from a reputable manufacturer should provide a very high reliability from the unit (in addition to a much smaller size). I am using 12k duty caps for my recapping and am not concerned with their reliability. I also don't think ripple current handling in this application is very demanding.
Rax:

--- Quote from: Vertamps on June 25, 2024, 12:56:55 pm ---Hello, let me install one first so im not sending out files with an issue. Ill try to tonight after work (sorry wait one more day ;) ). Worse case my spacing measurements are off by a mm. Mating hole size board to board are 1.2mm to fit 1mm/18 gauge solid
core copper wire.

--- End quote ---

Assuming you get the spacing right, what do you plan to use for the five leads going to the unit's board? Is that the 18 gauge solid core wire? If yes, I wonder if you've figured a convenient way to attach them to the adapter PCB for soldering. Unless you're using some PCB mount header pin type that snaps onto the board or something similar, I assume keeping attached for soldering five terminals to each of the boards makes the recapping very laborious.
Vertamps:

--- Quote from: Rax on June 25, 2024, 03:14:35 pm ---
--- Quote from: Vertamps on June 25, 2024, 12:56:55 pm ---Hello, let me install one first so im not sending out files with an issue. Ill try to tonight after work (sorry wait one more day ;) ). Worse case my spacing measurements are off by a mm. Mating hole size board to board are 1.2mm to fit 1mm/18 gauge solid
core copper wire.

--- End quote ---

Assuming you get the spacing right, what do you plan to use for the five leads going to the unit's board? Is that the 18 gauge solid core wire? If yes, I wonder if you've figured a convenient way to attach them to the adapter PCB for soldering. Unless you're using some PCB mount header pin type that snaps onto the board or something similar, I assume keeping attached for soldering five terminals to each of the boards makes the recapping very laborious.

--- End quote ---
The solder holes on the fluke are larger to accompany the original caps, if i remember not all of the ground lugs are connected to ground so its universal to keep all the mounting holes filled or not. For a one and done project the extra time to install is fine, i will try 1mm headers and show if it works. After thinking about it I will also make a spacer pcb file with no copper layer, just the drill holes. Could just remove the layer files and reorder but it won't take long, ill add some overlay info. You could stack the pcb standoffs and solder the mounting leads if using solid wire to keep em more straight. Copper is flexible and im sure there's a way to pinch them in or just clip extra lead length after install. Ill really try to reply tonight with an update, maybe quick video. I found some 3mm adhesive trips at work im gonna use as a spacer for now.
Rax:

--- Quote from: Vertamps on June 25, 2024, 04:09:43 pm ---The solder holes on the fluke are larger to accompany the original caps, if i remember not all of the ground lugs are connected to ground so its universal to keep all the mounting holes filled or not.

--- End quote ---

That's right - see pic below - and to me using a bit of insulated wire to connect the ones needing it is fine. What's a bit more messy is cleaning the board after soldering, given the conformal coating which gets charred by the soldering iron. But I feel the work is good and will be long lasting.
bastl_r:

--- Quote from: Vertamps on June 25, 2024, 12:44:19 pm ---
Well, i suppose if you wanted to pick out 3 skinny/tall capacitors you could parallel them for lower ESR than the original capacitor and fit them on the pcb size.

--- End quote ---
The ESR will only play a subordinate role here. I therefore see no need to use special electrolytic capacitors. At most some with a view to a longer service life.

bastl_r
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