Hello, i have a recently adquired a very nice and clean $200.00usd Agilent 34401a, everything works good but 2w ohms, i already dissasembled and clean S1 swith, by the way it was already very clean and shiny both contacts and whipers, i checked every 24k resistor and they measure good in every series combination and contacts possible and values are right 24k 48k 72k in all of the 12 resistors (front and rear) so no bad contacts or cracked solders, both front and rear exhibit very close readings, when turning on with shorted 2w, a reading of almost 9 ohms is obtained and with time decrease, after 2-3 hours reach 0.05 ohms aprox. during this time both front an rear decrease readings in very similar values. null zeroing drifts too.
from the begining all tests pass,
i already reflow S1 switch, inputs, k101 relay, cleaned inputs with deoxit and cotton sticks, no luck
heat affecting components?, transistor ladder
(4w works good, only last digit moves a bit, maybe pomona minigrabers fault) ?
any clues?
any help will be really appreciated.
best regards.
Pio