A. APPENDIX B ANALYSIS OF CHANNEL 8 OPERATION DURING BOOST POWERING THE LOW CURRENT REGULATOR (LCR) BY STEPPING THE coil. Ο In a normal mission the K, relay in the command switch is reset for the last time by a switch in the blockhouse panel which momentarily connects the P-battery to the K, reset At S+17 the hydraulic timer is actuated by Agena Separate to close a set of contacts pulling the K, relay into its set conditions. (This is the Cruise Mode-On Command.) As K, is set, it provides P-battery voltage directly to the input of the Low Current Regulator (LCR) resulting in a regulated -27.5 vdc to power the Channel 8 telemetry components. (See Figure B-1.) The K, relay will also provide power to the LCR when it is set by the command switch being driven to its warmup position. The previous movement of the command switch from emergency off to zero causes the K, relay to be reset. A subsequent command switch advance to warmup sets the K, relay with Channel 8 telemetry initiated. Three additional, or any integral four-combination, command advances will return the switch to zero, resetting the K, relay and turning the Channel 8 telemetry off. The two telemetry points, Point 1, Channel B unregulated voltage, and Point 2, LCR output voltage, were present in the RA-6 Channel 8 telemetry presentation. This is a strong indication that Channel 8 received its power from the LCR. The actuation of K, put P-battery voltage into the LCR and also actuated K, of the Distribution Control Unit (DCU) transferring the Channel 8 drive to the output of the LCR. These events are the same as those which occurred in the RA-6 flight. Since LCR output voltage was recorded on telemetry at 26. 4 during the inadvertent turn-on, two tests were made on the PTM at RCA to determine nominal input voltage and output drains that would establish this output voltage. Test No. I indicated that, with a nominal 0.250 amp drain, the input voltage had to be set to a 27. 3 v to maintain a 26.4 v output. Test No. 2 indicated that with a constant 34.4 v input, the drain had to be established at 0.575 amp for a 26. 4 v output. Additional test data on the LCR were extracted from the TA Log Book. Test results are shown in Table B-1. Table B-1. Low Current Voltage Regulator TA Log Record There are several failure mechanisms that will cause the P-battery power to be applied to the LCR and hence to the Channel 8 telemetry, and one failure mechanism which can reset the K, relay if it is intermittently failed set. However, these do not account for all of the events as they occurred. The LCR will receive power if the transfer contacts of K1 can be effectively shorted, such as a short circuit between pins 38 and 39 of A13J1 on a Cannon connector in the command switch, or if the K, relay contacts can remain closed for 67 seconds without the relay latching. Removal of Channel 8 telemetry for these situations would depend, in the first case, on the short lifting; and in the second case, on the acceleration causing the closure to be removed. These cases are possible but considered unlikely as causing the specific RA-6 failure. A test was run on the K1 relay and is described in Table B-3. |