Modification list for the final XL2
===================================

+15 and -15 need to be reversed on OP177Gs
  -lift pins 4 and 7 of U138 and U140
  -connect pin 4 to pad of pin 7, and pin 7 to pad of pin 4
 
Connect pin 9 of U10 via a 1k resistor to GND

Add 0.1uF capacitor between TP155 and GND (???)

REF-02C needs to be grounded at U139 pin 4.  Connect pin 4 to
   side of R171 physically closest to U139

Connect TP112 to TP120 to enable 1/n counter (with n=8)

--------------------

new mods are as follows: [July 15, 1997]

for data bus:

* lift U95 pins 12, 13.  connect pads together.
* lift U141 pin 8.  Connect pin to pin 13, U95.  Connect pint 12, U95 to U141
  pad 8.   

for DTACK:
* lift U119 pin 4.  Connect pin to U141 pin 9. lift U119 pin 12, connect pin
  to VCC.

--------------------
HV Mods [ Aug 5, 1997 ]
------

For interlock control:

 - replace R17 with 100 ohm resistor (was 1.5 kohm)
 - add diode on top of R127; orientation: arrow toward VCC

For HV control:

 - jumper TP111, TP136 to ground (sets 0 to 10 V programming voltage)
 - jumper TP128 with TP 130; jumper TP146 with TP147
	(this sets common to ground)
 

Modification for PMTIBP clock signal 11/17/97 D.M.
===================================================

 - Remove 5.1 K Ohm 805 resistor from spot R1
 - Replace it with a 75 Ohm (or close to it)
 - Piggyback a 470 pF capacitor on the 75 Ohm

Note: as of 11/17/97 this has only been done on 2 XL2's at Penn and the
      XL2 at TRIUMF (the one on the HV teststand not the other).

Modification list for the XL2 for use with Bed-of-Nails
=======================================================

[see xl2-bed-of-nails.modlist in this directory]