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We had to replace SDCC and TCPS cards in <R> core. R core power supply switched off in <PD> and subsequently the TCPS card was replaced. When we disconnect the JP1 connector in TCPS card the following alarms are generated and drives were getting on and off:

<S> 0047 DCC I/O card Obj ID#4 reset (diagnostic alarm)
Emergency LO pump running
Fire in Zone#1, 2, 3
Manual trip local & remote
Normal shutdown protective lock out
Customer trip
Hydraulic protective trouble
MCC under voltage

We suspended the work as the machine was on turning gear and turning operation was getting interrupted.

We have done the same exercise after stopping the turning gear. This time we found that TCD1 card was rebooting (changing A2 to A7 state continuously) when JP1 connector is disconnected in <R> computer TCPS card.

Each core is equipped with TCPS card and it supplies the required voltages to cards in that core. Something is wrong in our system. Anybody has this kind of experience? Please share with me.

Regards,
ankarao

If you look in the Mark V Maintenance Manual, GEH-5980, you will see that all of the cards which are associated with a particular processor are not located in the "main" core of that processor. In the case of the TCDA cards in <QD1>, they get their power from the TCPS in the core with which they are associated, or at least the processor they should be associated with. The TCDA in Location 1 is <R>'s TCDA; the TCDA in Location 2 is <S>'s TCDA; the TCDA in Location 3 is <T>'s TCDA. In your case, it would seem that if you powered down <R> and the TCDA in Location 2, which is associated with <S>, shuts down, and the TCDA in Loc. 1 did not power down which should be powered by <R>'s TCPS, then the power supply cables to the two cards must be swapped by mistake.

You should be able to look at the labels on the connectors and they should tell you which location each one should be plugged into.

I suspect the TCDA power supply cable from the TCPS in <R> is plugged into the TCDA in Location 2, which should be powered by the TCPS in <S>. You can also verify this by powering down <R>, and observing the three TCDA cards in <QD1>. If the LEDs on the TCDA in Location 1 don't go out, but the LEDs on the TCDA in Location 2 do go out, then it would seem that <R>'s TCDA power supply cable is plugged into the TCDA for <S>. Now you just have determine where <S>'s TCDA power supply cable is plugged into, but that should be available from the labels on the cable connectors. They should say something like 'JP1, Loc. 1' or JX1 Loc. 1' etc. (I don't remember what the power supply connector cable designation is on the TCDA cards, but it should be the cable with several 16 AWG single conductor wires (i.e., not a ribbon cable).

Thanks for your reply.

We conformed that cables are not swapped. If that is the case, as soon as R core power supply is down <S> TCDA card would have lost the supply. It happened when <R> TCPS card connector JP1 was removed.

It looks like a mystery to me. Once <R> power supply is switched off in <PD>, there should not be any supply in TCPS card.

We have disconnected the <S> TCPS connectors for gel application but we did not face any abnormality in other cores.

Thanks for the reply.

We confirmed that cable swapping has not taken place.

If that is the case, as soon as R core is down a disturbance must occur in S core. The problem arose during removing the connectors from TCPS card. In fact, TCPS card supply is already down (R core supply switched off in <PD>).

Thanks and regards.