Hello, I am attempting to install a second channel in one of these analyzers and have successfully performed this mod before, twice. Now apparently there is something that needs to be done if I am dealing with a unit with serial number previous to 3641A (or something close) according to the online manuals I am supposed to contact Agilent for some reason. Symptons are... after installing any second channel A20 board the unit will not power up. I have turned the option on internally and changed the single/dual channel jumper on the A35 board and still nothing. I have even installed another power supply from a working unit which has two channels??? Still nothing. Any help would be greatly appreciated.
In general, you cannot mix A20 and A21 boards within an instrument and the passthrough board (A70 or A71) needs to be the correct one for A20 or A21 boards installed.
Use A70 with A20
Use A71 with A21
The attached two service notes describe issues that you should be aware of when swapping boards between instruments. We suspect that service note 89410A-12 will fix the issue described.
Regards -