2465B CH1,2 compression


Rebonjour a tous:
Same low SN B062 2465B
has extrême CH1,2 compression on lower part of display.

CH 3, 4 are perfect and normal.

Photo Album: 2465B CH1,2 compression

Taken with 100 kHz triangle on CH 1 and CH2,
position upper nearly linear position lower screen, extreme compression and non linearity.
Transient response is also severely affected as position of traces is moved.

1/ all PSU voltages normal,

2/ using substitute A5 so no CAL data is valid.

3/ Is there an adjustment or bias eg on U400 channel sw ?

4/ Pulled U400, cleaned the hybrid contacts, no change

is there a place to test signals into U400 from CH 1,2 preamp U100, U200?

Assume U400 155-0236-00 is bad and replace (VERY costly!)

Many thanks


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