TU-4
The Tektronix TU-4 is a plug-in for testing 560-series oscilloscope mainframes including the Type 506. It contains load resistors for testing the power supplies of the scope. These apply different loads to the early 560, low power scopes, versus the later 561 and other, higher power scopes in the 560 family. It has a Signal Input connector for driving the vertical deflection plates directly, with no amplification, and it has a Z-input for testing the Z-axis function of the CRT circuit.
There are two neon lamps on the TU-4 front panel that are intended to show whether the AC line input power of the scope under test is connected correctly. The functioning of these lamps depends on 117 VAC hot and neutral being connected to pins 7 & 8, respectively, in the plugin connectors of the scope being tested. This will work even if the scope being tested is wired for 234 VAC. These pins were not connected in later models of the 560 series. Consequently, the neon lamps do not work when the TU-4 is used with a 561B, a 564B, or a 568 (SN 288 or later.)
Note that some of the photos on this page show a TU-4 with BNC connectors instead of UHF connectors. That was a change that was scheduled to start at SN 300, but production never reached that point. Only the UHF connectors were scheduled for that change; the binding post was not part of the planned change. While BNC connectors are a welcome improvement, the TU-4 with BNCs shown on this page must have been upgraded after it was sold.
Pictures
-
Front w/UHF connectors
-
Front w/BNCs
-
Left
-
Left
-
Right
-
Top
-
Bottom
