Electronics > Repair
Fluke 343A repair
70bytes:
Nice to hear.
I replaced all the electrolytic capacitors. Most of them measured still fine. The oldest component i could find was from week 18 1968.
2 of the big capacitors were bad. 1 was replaced earlier. I read somewhere that the sprague capacitors mostly are bad.
bastl_r:
Hi
Unfortunately I don't look in here every day...
I could have told you about the flap.
There is a 1Ohm resistor behind the lower flap which burns out if the connections are short-circuited at a high output voltage or if the overvoltage arrester of a measuring device responds. Then the protective circuit is activated immediately when the power is switched on. Please don't ask how I know this.
I have now also received my "new" Fluke343. As it looks inside, it is still in its original and very clean condition. So it still has the original capacitors.
Unfortunately, of course, it has a small problem...
The zero points are shifted. However, the deviation matches the range.
7.998mV in the 10V; 79.97mV in the 100V; and ~800mV in the 1000V range so I suspect a common error. The offset then also runs through all stages with the same deviation.
The respective settings seem to fit exactly so that I don't want to adjust anything for the time being, although I'm sure from my 341 that I couldn't adjust that much with the zero adjustment.
Should I start a new thread for this? I think so. Or what do you say?
@Maurice: How did you cleaned the switch contacts?
bastl_r
coromonadalix:
deoxit should clean correctly the switches, and do verify the shafts extenders they crack and become loose
Rax:
--- Quote from: bastl_r on June 23, 2024, 11:52:31 pm ---How did you cleaned the switch contacts?
bastl_r
--- End quote ---
I also used Deoxit (D5), though I'd recommend holding off from using it on any of the output adjustment switches. For those, I'd just use IPA to clean them, and if I'd conclude they need conditioning (mine don't seem to), I'd very parsimoniously apply a bit of Deoxit on the copper contact surfaces only. I'd be very careful not to spill any on the substrate of the switch. But I'd leave them alone if they operate OK.
Another contact conditioner I came to like is MG Chemicals 801B. Very expensive, but seems to work very well. It helped me bring back to life a few DM501As that otherwise have been very reluctant to work reliably.
bastl_r:
Sometime, it is a good recommendation to read the ****ng manual! |O
On page 35 ist the solution for my problem, i think.
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