HP Agilent 54610B DSO

[QuantumCheese]

Hi,

Recently my old DSO blew up So in the spirit of Monty Python, I bought another one
Blow me if it's not got a blown/faulty Ch1

One real strange bit is if you set ch1 to 200mv/div and have the test wave form going into ch2, a mysterious 2nd trace appears (that mimics what ch2 is displaying). adjust the ch1 range setting and it vanishes but go back to the 200mv setting and it's back.
It's HP 54610b but shares a great deal of similarity with the whole 546xx range.
I'm suspecting the attenuator stage on the front end as after that it's just digits (i believe)

Additionally i think it's a 'bit noisy' ie i would expect the ch2 waveform to look a bit cleaner, though that could just be me as i do prefer a nice clean line as displayed on my analogue scope!

Any help appreciated. I've found some user guides, but no real service manual as yet (been to google & electro tanya etc).

So far all the self diagnostics check out OK and the output of the LT power supply (5.1 and +-15 measure within spec)
I would like to make some measurements on the output of the 'front end' with known inputs, but it would be handy to know what to expect!

Cheers

Carl.

 

[QuantumCheese]

Well, it's not the front end. Blast.
It's nicely modular so i swapped ch 1 & 2 round hoping the problem would go with it. Nope.

I think some of the previous description can be ignored. that was a case of a 'kind person' setting it up to display almost total gibberish.
i think i now have a handle on how it's driven, ch1 is definitely doa, so i'm back to the drawing board without a schematic