[SOLVED] Agilent 1660ES ... channel one stop working ..

[saronno]

Hi to everybody.
I have a problem with my scope (that is actually a logic analyzer with scope integrated) ...
today I turn it on after a couple of months and .... scope channel one doesn't work anymore.
It's a bit unusual, since the last time I used it everything works fine.
Channel two instead works correctly.
My guest is that something related to a solder joint or a electrolitic caps has gone bad.
And another thing make me think it's nothing serious is that you can see the rumor
captured on the channel  .. so I don't think it has completely gone bad ... probably
a solder joint or however something between the pre conditioning and the A/D (the scope is digital)

So .... has anybody got a service manual for this scope/logic_analyzer ?

Any idea/suggestion?

PS: I exchange the probes and both works on channel two.
I will post some photos when I have enough time to take it apart ...

[saronno]

Here's some updates.

As you can see, channel one picks up some rumor



If I try to connect a battery (just for example) rumor increase
but no signal is picked up.



It can't be completely bad if it picks up the additional rumor ...

[saronno]

Mmmm ... no one? 

Does anyone have an idea about how preconditioning is working in this scopes?
What could cause rumor going throug but not signal?

white rumor is evenly distribuited in frequency .... to be picked up all the bandwidth has
to be good ... or at least most of it.

At the moment I have no idea of what could cause this behaviour. 

[free_electron]

noise passes. dc doesnt... the input scaler may be stuck in a range. change range(volts per div)  and ac/dc coupling : do you hear the relays click ?
it could be the relay driver or the relay itself.

the scaler is a metal can with the preamp , divider and relays in it . you can find them on ebay for about 120$. they are pretty easy to replace( no soldering required. two screws and they pop- off ). can't be fixed as they are hybrids with bare chips , vapor deposited resistors and caps and relays they are spot-welded in. the relays are custom designs from HP )

if the A/D or FISO would have failed the scope would give an error message..

http://www.ebay.com/itm/54512-63402-also-54512-63401-Attenuator-preamp-1NB7-8303-tested-cald-/261159789023?pt=BI_Oscilloscopes&hash=item3cce5621df

[saronno]

noise passes. dc doesnt... the input scaler may be stuck in a range. change range(volts per div)  and ac/dc coupling : do you hear the relays click ?
it could be the relay driver or the relay itself.

Relay works. If you change the volt per div you can clearly hear it.
Whatever the cpupling mode is (dc or ac) behaviour is the same.

the scaler is a metal can with the preamp , divider and relays in it . you can find them on ebay for about 120$. they are pretty easy to replace( no soldering required. two screws and they pop- off ). can't be fixed as they are hybrids with bare chips , vapor deposited resistors and caps and relays they are spot-welded in. the relays are custom designs from HP )

Ok, of course the machine has a good value so investing 120$ is good deal,
but I want to be sure.
Maybe it's possible to use channel two scaler on channel one and see if this solve the problem.

if the A/D or FISO would have failed the scope would give an error message..

http://www.ebay.com/itm/54512-63402-also-54512-63401-Attenuator-preamp-1NB7-8303-tested-cald-/261159789023?pt=BI_Oscilloscopes&hash=item3cce5621df

Exactly. That's my point.
Internal test of course are all passed.
I even downloaded the software from agilent and
did a complete test ... everything fine, all test passed.

[free_electron]

swap the cans.
if the problem moves : can problem.
does the relay click if you change ac/dc ?

they can get stuck .... they have mechanical memory ( they are latching relays )

also check that the center pin of the bnc is not broken off !

[saronno]

swap the cans.
if the problem moves : can problem.
does the relay click if you change ac/dc ?

they can get stuck .... they have mechanical memory ( they are latching relays )

also check that the center pin of the bnc is not broken off !

I have three mode 1M DC, 1M AC and 50 ohm DC.
If you change between 1M DC and 1M AC no click, but if you change to 50 ohm DC you can clearly hear the click
and you can hear it again if you switch back to 1M AC.

However thank you, because now I have some clues of what the problem is.

When I'll find the time to take it apart I will try to exchange the cans and I will update
the thread.

[saronno]

Bingo !
Thank you very much free-electron.
I took apart the scope (what a job, you have to dismantle everything to swap the cans)
swapped the cans and .... both of them now works !

So, it was just a little contact problem with the connector on the board.

Nice job. I owe you one. 

[saronno]

Some photos I made during the swap ...