Mark V C-core Problem


Thread Starter


Have a problem with my C-core. The C-core boots up to "C A4 BAD EEPROM C SUM" Checks has been carried out on the terminations of the interconnecting cables on the TCCA, SDCC, SLCC and TCDA card without any result.

The IO States on the C-core is as follows:
TCCA--A4,(TCDA shows)****--**,LCCB--A4,DCCB--00,IOMA--A3.

TCCA, TCDA, SDCCC and SLCC cards have been replaced without any result. EEprom formating and download has been carried out without any result.

"Check" command to the C-core also indicate okay for the downloaded files. Card_id command to the C-core does not show the revisions for the SDCC and TCDA. The only thing i am thinking of now is the eprom changeout on the SDCC card.

unfortunately i don't have a spare.

Looking forward to hear from you all. thanks.
You didn't say what happened before the failure to boot past I/O State A4.

The 3PL cable that connects the SLCC to the SDCC and TCCA can quite often be a real problem. There are no pull tabs on that cable and if it's not unseated with care the connections can come apart.

Are you absolutely certain of the hardware ("Berg") jumper positions?

The EEPROM chip is the U9 chip, I believe. That chip has been known not to withstand as many downloads as the manufacturer suggests. It is a fairly chip and one can be easily purchased and replaced.

Another common cause of this problem is improper placement of the PROM chips (EPROMs) in the sockets. Some of the chip sockets have more pins than the chips, and a common mistake is to put the chips in the sockets with the notch of the chip in line with the notch of the socket. The chip must be placed in the socket with the non-notch end of the chip at the non-notch end of the socket. You should be able to look at the SDCC card in one of the other cores to see how the chips are lined up. Sometimes (but for some strange reason not always), if the chips are improperly seated and power is applied, they fail, and new PROMsets must be purchased by GE.

Another common mistake is to mistakenly swap the PROMs chips (they usually are pairs of chips) and if powered-up, this can also cause the chips to fail, again, sometimes but not always. The chips have numbers on them that should correspond to the numbers silkscreened on the card. Again, the same cards are used in the other processors so you should be able to check them to see how the chips are placed.
Thanks for the response. The problem occurred as result of a power down and power up. The cable 3PL mentioned have been checked and is seated properly. Lubrication of this leads have also been carried out.

I can confirm that the chips U11, u12, U22 and u23 have been installed properly and firmly seated.

Best regards,