HOW TO SWAP A XFT LINKERBOARD
-------------------------------

If power light is off, then try replacing the fuse.  There are spare fuses and
a voltmeter in the XFT cabinet.  Check the fuses with  the voltmeter and
replace if necessary.  Linker boards take a 15A and a 3A fuse.  

Spare linkers are in the stereo crate, b0xft06, and in the spare rack on B0
2nd floor outside the pump room.

How to replace a linker board:

1. Switch crate power off, disconnect cables.
2. Remove board.  Note serial number.  If faulty, mark with an orange sticker.
3. Check the delay switch settings on spare. There are a few boards with special 
settings due to faulty delay switches, but the settings should be
SW701 = 567 and SW702 = 3 or 4 or 34 for most linker boards.
4. Replace with spare, note serial number.
5. Power on crate, reconnect cables. 

6. vxlogin b0xft0? to watch for errors from actions below.  Logout when finished.
7. Bring up xftdaq GUI under the cdf_xft account - see "How to start XFT
diagnostic GUI" for instructions.  ENSURE MYXFT0?.CRATE HAS CORRECT SERIAL NUMBER.
This is important since the flashram is downloaded with this serial number.
If there is a conflict between this number and what the hardware database
expects, COLDSTART will fail.

8. Bring up the NLinkerboard panel.

9. Go to FlashRAM Loading page.  Read Flashram Label.  Look at flashram designs
on neighbouring boards to figure out the correct one to download. In the
example below, where the new board is in slot 10, you can deduce that it should
be downloaded with b6_r0p4.rbf:

slot 4	contains b3_r0p4.rbf
slot 6	contains b4_r0p4.rbf
slot 8	contains b5_r0p4.rbf
slot 10	contains *********** <- new board
slot 12	contains b7_r0p4.rbf
slot 14	contains b8_r0p4.rbf
slot 16	contains b9_r0p4.rbf
slot 18	contains b10_r0p4.rbf

10. Choose the correct file with the Choose rbf file button.

11. Select current linker only and click bar at bottom of GUI to move to the
correct slot, click tab at top of GUI to move to correct crate
(YOU ONLY WANT TO ERASE/DOWNLOAD ONE BOARD!)

12. Click on FlashRAM lock checkbox to unlock dangerous GUI buttons. Click EraseFlashRAM
13. Click on FlashRAM lock checkbox to unlock dangerous GUI buttons. Click DownloadFlashRAM.
The FlashRAM will be downloaded and then the FPGAs will  be automatically
reprogrammed with the new design from the FlashRAM.  

14. Check for error messages in text window.  Read FlashRAM label and Find
design in FPGAs to check for success.  If blank, something is wrong!   Note any
error messages on the vxlogin cpu screen or on the GUI message panel. Repeat
from step 11.

15. Go to multiple linkerboard test page.  Run multiboard test for the standard
design. If CDF is not losing data due to xft problem, run 33ns test - see "How to run
linker internal connection test" for instructions.

16. Update hardware database with the new serial number.
17. Try doing a coldstart yourself a few times, to see that it works reliably.
18. Return crate to shift crew.

19. Make an entry in the XFT elog that describes the problem with the original
board in b0xft0?, slot ??, gives the serial numbers of the boards exchanged and
notes any complications with FlashRAM reprogramming etc.