3M1/Repairs: Difference between revisions

3M1/Repairs (view source)

4 bytes added , 22 September 2023

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typo, some rewording

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-In order to allow my 3M1 to work with 40 V pulses, I added a second resistor in parallel to R104 increasing the quiescent bias point of the 6DJ8. The resistor I added was a 620 kΩ, and the resulting parallel combination measures ~185 kΩ. This now works perfectly in my 564B. It should work equally well in any 560 series scope.
+In order to allow my 3M1 to work with 40 V pulses, I added a second resistor in parallel to R104, increasing the quiescent bias point of the 6DJ8. The resistor I added was a 620 kΩ, and the resulting parallel combination measures ~185 kΩ. This now works perfectly in my 564B. It should work equally well in any 560 series scope.
-You can see the extra resistor piggy-backed on R104 in the last two photos on that page.
+You can see the extra resistor piggy-backed on R104 in the last two photos on the 3M1 page.
-It's worth noting that the input circuit in the 3M1 is different from the middle 9067-0500-00) version. The middle version has a Zener diode in the center of that resistor chain. That version may require a different approach, but the approach above should be a good start.
+It's worth noting that the input circuit in the 3M1 is different from the middle (067-0500-00) version. The middle version has a Zener diode in the center of that resistor chain. That version may require a different approach, but the approach above should be a good start.
 [[Category:Instrument repair reports]]