Uni-T UT61E Multimeter repair [4/4]

Опубликовано: 27 дек. 2015 г.
Finishing the repairs on the Uni-Trend Multimeter. It is now fully functional.
1ss268(in scheme D4) can be replaced by bat54c.

1ss268(in scheme D4) can be replaced by bat54c.

I've used a 5k resistor... and it seems to work fine. For some reason.. smaller resistors heated when on Ohm measurements. My D4 was ok.. but not the pullup, so i suspect that your reset is related to the diodes used as mine doesn't do any reset.

I've used a 5k resistor... and it seems to work fine. For some reason.. smaller resistors heated when on Ohm measurements. My D4 was ok.. but not the pullup, so i suspect that your reset is related to the diodes used as mine doesn't do any reset.

Sehr schön gemacht, auch wenn ich nur ca. 70 % vom sprachlichen verstanden habe, so ist das Thema und Sinn des Videos aber rübergekommen. Schade, dass du die meisten Videos oder im Prinzip fast alle auf Englisch erklärst. Ist eine Interessante Sache die Elektronik, da findet man leider nur wenig Deutsche Informationsvideos darüber. Daher ist es etwas Schwierig, da man nun hier die Sache an sich die im Video vorgetragen wird versucht zu verfolgen und zu verinnerlichen plus noch die Sprache verstehen und richtig zu deuten, bzw. übersetzten. Vielleicht kannst du ja mal ein paar deutschsprachige trotzdem mit einbauen in deinen Kanal ;)

Sehr schön gemacht, auch wenn ich nur ca. 70 % vom sprachlichen verstanden habe, so ist das Thema und Sinn des Videos aber rübergekommen. Schade, dass du die meisten Videos oder im Prinzip fast alle auf Englisch erklärst. Ist eine Interessante Sache die Elektronik, da findet man leider nur wenig Deutsche Informationsvideos darüber. Daher ist es etwas Schwierig, da man nun hier die Sache an sich die im Video vorgetragen wird versucht zu verfolgen und zu verinnerlichen plus noch die Sprache verstehen und richtig zu deuten, bzw. übersetzten. Vielleicht kannst du ja mal ein paar deutschsprachige trotzdem mit einbauen in deinen Kanal ;)

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it should not need such a low value resistor to keep that pin to 0v, i would disconnect one side of the resistor, then remove the switch so all contacts are open, then measure resistance from 0v common to each of the Function lines. They all use the same logic so they will have identical internal pull up resistors, except for the faulty one. Its unfortunate that you may find its the processor that has damage :-(

it should not need such a low value resistor to keep that pin to 0v, i would disconnect one side of the resistor, then remove the switch so all contacts are open, then measure resistance from 0v common to each of the Function lines. They all use the same logic so they will have identical internal pull up resistors, except for the faulty one. Its unfortunate that you may find its the processor that has damage :-(

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Habe mir mal bei ebay ein altes Voltcraft Mutimeter der Mittelklasse gekauft, kennst du vielleicht eine open source Software für den RS232 Port des Multimeters ? Die beigelegte Diskette ist nicht mehr lesbar.

Habe mir mal bei ebay ein altes Voltcraft Mutimeter der Mittelklasse gekauft, kennst du vielleicht eine open source Software für den RS232 Port des Multimeters ? Die beigelegte Diskette ist nicht mehr lesbar.

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Good job!

Good job!

Amazing! I was not expecting the value of the resistor to be that low, but whatever works, I guess. Believe me, that fix doesn't look ugly at all :P

Amazing! I was not expecting the value of the resistor to be that low, but whatever works, I guess. Believe me, that fix doesn't look ugly at all :P

Nice work getting it together. The fact that you need such a silly low value pull-up suggests that you've got something pretty bonkers going on at that pin. Perhaps it's a shorted input buffer transistor that's just gone more or less short across all pins; in such a case, you would expect it to have a low impedance to both ground and the actual input of the circuit, and you'd need to overcome its resistance to ground in order to raise the signal level going forward into the rest of the IC - ergo requiring a strong pull-up. It would be fun to see if the short could be "blown away" by applying a relatively large energy burst to the input, but that would also drive the circuit on the other side of the transistor way out of its boundaries, and would probably make the input fail completely - so I don't recommend doing it!

Nice work getting it together. The fact that you need such a silly low value pull-up suggests that you've got something pretty bonkers going on at that pin. Perhaps it's a shorted input buffer transistor that's just gone more or less short across all pins; in such a case, you would expect it to have a low impedance to both ground and the actual input of the circuit, and you'd need to overcome its resistance to ground in order to raise the signal level going forward into the rest of the IC - ergo requiring a strong pull-up. It would be fun to see if the short could be "blown away" by applying a relatively large energy burst to the input, but that would also drive the circuit on the other side of the transistor way out of its boundaries, and would probably make the input fail completely - so I don't recommend doing it!

Well done for fixing it

Well done for fixing it

Great work.

Great work.