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Hello Keith,
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a few friendly hints included below. Good luck, Magnus * Yes, you can operate the so-called acquisition unit alias the lower part without the display unit. But you need to carefully disconnect the Pomona coax connectors J3112/J3113 which connect to the HV board. And, please leave at least one board in the acquisition unit connected, so that the switched-mode power supply has a minimum load to operate properly. * The complete power supply including the rectifier and filter assembly or PCB/ A31 and the Power supply and inverter board assembly/A30 can be pulled out for servicing. Please obey general safety rules and refer to the service manual, as the power supply can store lethal energy even after it has been switched off. * My #1 hint would be to check the power supplies with the other assemblies or boards disconnected (again, min. 1 board connected), and connect them step-by-step while checking the power supples. And to do this thoroughly. Also, check the main interconnect/plug-in sockets board, as several group members including myself have found shorted tantalum caps on this board. As you have said, the board-to-board connectors are also worth a check. And there are many in the 7704A... * I have found Tektronix' trainings material named "7704A maintenance training handout" an irreplaceable source of information. Dave with artekmedia.com sells an excellent copy (I am not affiliated with Dave, just a satisfied customer). * The 7704A's switched mode power supply is a complex design and tough to troubleshoot. But, there are some very knowledgeable members in this group - so you are in the best capable hands, if you need further advice. Keith Smith kahsmith@... [TekScopes]:
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