Work on Quick Dipper Probe VI ------------------------------- Original Rev. 19-Apr-2022 Current Rev. 27-Apr-2022 Wiring Inside this QD-VI Probe: ------------------------------- One side of the box at the top of this probe is the Voltage side and the other side of the box is the Current side. Each side has a 7 pin Fischer connector. Pins 1 through 6 of each Fisher connector runs to a sample contact down at the bottom end of the probe. Pin 7 of each Fischer connector is tied to "Chassis Ground", i.e. it is electrically connected to the die cast box and to the stainless steel tube of the probe. With the probe in its vertical operating position and looking at the flat surface of the sample mounting area, the upper row of contacts are the Current contacts and the bottom row is the Voltage contacts. In each row the contacts are numbered 1 through 6 going from left to right. Contact number 1 is connected to Fischer pin 1 ... contact 6 to pin 6. Each of these 12 circuits from a Fischer connector pin down to a sample contact also connects to its own "Grounding Switch". When the lever for one of these Grounding Switches in down then no additional connection is made to that Fischer pin to sample contact circuit. When the switch lever is up then the Fisher pin to sample contact circuit is also tied to a common "Grounding Bus". There is a separate Grounding Bus for the Voltage contacts and the Current contacts. One each side of the box there is a 7th switch so that these two Grounding Buses may be either directly connected to the Chassis Ground or connected to Chassis Ground through a 1 Meg Ohm resistor. When the switch lever is up then that side's Grounding Bus is directly connected to Chassis Ground. I have no understanding of the Fischer connector and 4 toggle switch on the top surface of the box. I don't think that any of these top surface connections are used in the current application of this probe. I also know nothing about the unused heavy copper leads that appear to run down the probe and are not connected to anything in the box at the top of the probe. Tests Made on the Probe Wiring: ------------------------------- 1. Circuit Continuity: The 12 circuits from the Fischer connector pins 1 through 6 down to their contact at the bottom of the probe were checked for continuity. They all measure about 15 Ohms except for Voltage lead #6 which measures about 17 Ohms. The Ohm meter used was 2 wire with a 1 mA test current. The resistance from Pin #7 in each Fischer connector to the Chassis Ground was check and with the 2 wire Ohm meter and measured as low as one could expect. 2. Circuit Isolation: The 12 circuits from the Fischer connector pins 1 through 6 down to their contact at the bottom of the probe were checked to verify that they were all isolated from each other and from ground (with the Grounding Switches open). In all cases the circuits appeared to be isolated from each other. The Ohm meter used would have indicated any leakage at the level of 100 Meg Ohms. 3. Circuit Grounding: With all Grounding Switches closed and the Grounding Buses connected directly to Chassis Ground the resistance between Chassis Ground and each of the 12 Fischer pin to sample contact circuits was checked. They all measured under 1 Ohm using a 2 wire meter with a 1 mA test current. 4. 1 Meg Ohm Grounds With the Grounding Bus switch on each side of the box in the position that should provide a 1 Meg Ohm connection between the Grounding Bus and Chassis Ground this resistance was checked and in both cases measured about 1 Meg Ohm. Work Done on QD-VI Probe on 18,19-April-2022: --------------------------------------------- - The die cast box was loose on its mechanical connection to the stainless steel tube of this probe. This mechanical connection was tightened. - The electrical connection from pin #7 of the Fischer connectors was very poor and loose where it connected to the die cast box. Holes were added to the die cast box so that solder lugs and external tooth star lock washers could be used to make this a serious stable connection. - The electrical connection from the die cast box to the stainless steel tube was flaky at best. This connection was improved and should now be stable. - Current side Grounding Switch #3 was broken and was replaced with a toggle switch that required opening up the mounting hole for this switch to 1/4" diameter. - Voltage side Grounding Switches #5 and #6 were both very flaky in their operation. This was traced to two wires that had never been soldered. - The cover plate for the die cast box was missing so a replacement was made. In one corner, when the cover plate is installed, it pushes against the signal wires inside the box - pushing them further into the box. On its inside surface, in this area were the cover plate touches some of the signal wires, it was covered with kapton tape. Work Done on QD-VI Probe on 27-April-2022: ------------------------------------------ - When Josh tried using QD Probe VI on 25-May-22 it gave bad readings. Josh tested it after the dip and found that Voltage Lead #6 from the Fischer connector down to the pad in the sample area was reading 36k Ohm. Note in the text above that Voltage Lead #6 gave a different reading than the other leads, just a few Ohms higher, when it was tested back earlier in May. - On the same day I checked that resistance of the full path and found 11k Ohms. The resistance of the path from the Fischer connector to the Grounding switch terminal for Voltage Lead #6 looked good. With more probing and flexing of the sample mounting perf-board the resistance of Voltage Lead #6 dropped down to the range of 15 to 20 Ohms. - The resistance of Voltage Lead #6 was tested on 27-May-22 without probing by soldering a AWG 34 Ohm Meter lead onto the flying wiring for Voltage Lead #6. The point of doing this was to eliminate the variations in the Ohm Meter reading caused by changes in placement and force on the normal Ohm Meter probes. With this setup it was clear that any movement of the long thin wire from the top of the QD probe where this wire is soldered onto the Bishops Graphics strip caused large changes in the Ohm Meter reading. It was found that the long thin wire from the top of the QD probe could be slide in and out of its "cave" of solder on the Bishops Graphics strip, i.e. Voltage Lead #6 was not actually soldered to the Bishops Graphics strip but just mechanically trapped there. - The long thin wire from the top of the QD probe for Voltage Lead #6 was re-soldered to its end of the Bishops Graphics strip. This lead was actually a little too short to cover all of its pad on the strip so a "splint" was used to lengthen it - see photo. - Using the two lead Fluke Ohm Meter the resistance of the 6 Voltage Leads are now: #1 15.59 #2 15.64 #3 15.79 #4 15.65 #5 15.76 #6 15.61 The #6 lead now looks like the rest of them. A minimum of force was used to push the Ohm Meter probe onto the Rose's alloy blobs for the flying leads so the Ohm Meter readings were not perfectly stable.