Dear collegues

In our power plant,there are two GE Frame 9E gas turbine with Mark V TMR control system.At DIAGC DATA Display-TCQAG1B for core R, the following voltages noticed:-<pre>
P5v = 5.11 vdc
P15a = -0.12 vdc (JE-29 = -0.02 )
N15a = 17.0 vdc ( 30 = 3.00 )
P15b = 9.45 vdc ( 31 = 1.55 )
N15b = -17.1 vdc ( 32 = -3.00 )
P125v = 1.98 vdc ( 33 = 0.04 )
N125v = 152.89 vdc ( 34 = 3.00 )

Also the power supply values of IOMA for same core are :-
P5 _ voltage = 0.00 v
P15_ voltage = 29.2 v
N15_ voltage = 0.00 v
P24_ voltage = 14.2 v
N24_ voltage = - 14.29 v
DCOM_VOLTAGE = 1.3 V

While the two other cores <S>&<T> are normal.
There is a diagnostic alarm:-
IOMA power supply out of limits,P5
P24
P15
N24
N15
DCOM</pre>
There is no intermittent, difficulties with the operation of the unit.
the following procedures done to fix the problem:

1.Supply voltage at <PD> is +65.44v & -65.40v.

2.Replacing power supply module TCPC of core R without result.

3.Replacing TCQA module without result.

4.Replacing TCQC module without result.

4.Replacing DCC & LCC module without result.

5.Exchanging DCC&LCC of core T with core R, so the problem moved on to core T, and all voltages at core R are correct, but both cores stayed at A6 status.

6.Returning DCC&LCC modules to original places, then replacing EEPROMs (DS200GHDQF1CBG 01&02 PDC04030810.1) (same version) OF DCC MODULE,download EEPROMs,A7 status, but without results (same problem returned)

Obviously a new core had been replaced (just the terminal boards not replaced) without any results.
Please advice me how to fix this problem?

thanks

 

What part of the reply to your previous posting about this problem did you not understand?

http://www.control.com/thread/1306407234#1306428361

You said you change the main DCC PROMset, but that's not a "PROM" upgrade. I believe the PROM upgrade for resolving the nuisance IOMA power supply Diag. Alarm is "detailed" in TIL 1480-2, and would likely involve changing other PROMsets as well.