T computer does not detect exhaust thermocouples

  • Thread starter P. Deb Choudhury
  • Start date

Thread Starter

P. Deb Choudhury

Ge frame 5 with speedtronic mark V control. T computer fails to detect values of Exhaust thermocouples.

same group of exhaust thermo couples when connected to R And S they can detect but T computer can not. checked cards except the main processor, suggest if anything to be checked further.

REGARDS. 4.4.2011.
<b>When did this problem start?</b> After a maintenance outage? After a card was replaced? If it was after a card was replaced, which card was replaced, and why was it replaced?

You can follow all of this by looking at the Signal Flow Diagrams in Appendix D of the Mark V Application Manual, GEH-6195.

<b>What Diagnostic Alarms (ALL of them) are being annunciated by <T>?</b>

All of the exhaust T/Cs are connected to the TBQA on <R>. The first 15 T/C inputs on the TBQA go to the TCQA card in <R> via ribbon cable JAR; the second 15 T/C inputs on the TBQA go to the TCQA card in <S> via ribbon cable JAS; and the last fifteen T/C inputs on the TBQA go to the TCQA in <T> via ribbon cable JAT.

So, if the T/C inputs connected to terminals 61-90 on the TBQA in Location 8 of <R> are not getting from the TBQA to the TCQA, then the problem is either the cable, JAT, is not fully plugged into the TBQA or the TCQA, or the cable is bad, or the TCQA is bad. Or the power supply to the TCQA is not working.

If I recall correctly, there are LED bargraphs on the TCQA cards. How does the blinking of the LED bargraphs on the TCQA card in <T> compare with the pattern exhibited by the TCQA in <R> and <S>? When everything is working correctly in all three processors, the LED bargraphs on the TCQA cards should all be blinking in the same pattern and at the same rate in all three processors. And, when they're not--there are ALWAYS Diagnostic Alarms to alert the conscious viewer to a problem or problems.

There have been many reports of problems with corrosion affecting the tin on the ribbon cable connectors and on the card connectors that the ribbon cables plug into.

What does "...checked cards..." mean? How were they checked? What were the results of "the checking"?

Have you done any downloads to <T> recently using the EEPROM Downloader? Specifically, I/O Configuration changes, or Control Constants?