| Electronics > Repair |
| Resistor Test problems Fluke 75 Series II |
| (1/1) |
| kdl1950:
Hello everyone, I have a problem again. This time with a Fluke 75. The error lies in the fact that a value of 0.00 ohms is not possible when measuring the resistance. If the input is short-circuited, the measuring device starts at approx. 20 ohms and runs to a final value of 1.2 ohms in approx. 1 minute. (see pictures). I have already tested internally without the connection socket. Same error pattern. Thus the bushings can be excluded. The cable is new and tested on other measuring devices. It looks like a capacitor is changing?!?! :-// Does anyone have an idea or knows the problem? I checked the various internal resistances. All OK. What is also noticeable is a similar problem with the diode/continuity test. It takes a certain amount of time until the value approaches 0.00. It won't be quite 0 either. Continuity testing works immediately and has no problems. Greets from Germany |
| m k:
Manual has Schematics. Get hair dryer and non conducting cold spray can. Warm up the thing with a hair dryer. If lower resistance value appears sooner than without the dryer move to the next step. Learn to shoot cold spray so little that only a single drop comes out. Put that drop on the suspicious component. You can also drop it on a single pin. With luck you find a source that is external. It can also be a dirty selection wheel. |
| steerage250:
Any luck solving this? (I have the same problem - and I don't want to through-away my faithful old Fluke!) I found a service manual for it on the Fluke website, but the schematic and component layout differ from my circuit board (the differences start immediately at the V/ohms input terminal where the schematic shows it connecting to 2 resistors, whereas mine connects to one resistor and the spark gap device) |
| kdl1950:
Hello steerage250, yes, there are insights and I can make it relatively short. I found the crucial clue here: "Fluke 77 III Resistance measurement fault" U1 has a defect or breaks. I heated the chip properly for a short time using a hot air dryer. The result is or was that the resistance measurement immediately goes back to 0.00 ohms. Unfortunately the measurement drifts away again after a few days. You can try it. The problem is definitely with the chip U1. I just reheated the chip. Here the result. From 0.02 to 0.00 in about 5 seconds. It remains to be seen how long the “repair” will last. At some point even a solid multimeter will reach the end of its life. |
| squadchannel:
Is it any chance that the solder has cracks in it? If it does not work after re-soldering, then give up :palm: |
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