Re: Restoring HP 1740A scope, strange waveforms seen, assistance please?
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I am not familiar with that model (I have a 1727A) but if it is anything close to the Tektronix 465, there are attenuator switches operated from the panel control that may be making poor contact.
I must get into my 465 to make such a repair.? I have a spare 465B and hope that one has the parts I need.
Bob
On Sunday, October 15, 2017 6:05 AM, "dadhills@... [hp_agilent_equipment]" <hp_agilent_equipment@...> wrote:
The signal is being differentiated, as if it is being coupled
through a small value capacitor.? I would first look at the
attenuator switch contacts on those particular v/div settings for an
open or high resistance.? In other words dirty switch contacts.
Dave
Hi all, I've been a member for a while but lurking in the
background while working on the scope and looking out for any
discussions about a 1740A taking place.
I now have the scope in a running condition after
replacing 2 faulty transistors and now while testing the scope
with the 1V test connection I discover that channel B works as
expected but channel A works OK up to 0.2V on the volts/div
switch, moving to 0.5V and upwards the trace goes odd.?
I was wondering if anyone could point me to the area that
I need to be looking at on channel A to cure the problem. I
have uploaded photos of? both channels with the settings on
0.5V and 1V so you can see the problem?
[url=][img][/img][/url][url=]B
channel 1V dc[/url] by
[url=]Graham
Butcher[/url], on Flickr
[url=][img][/img][/url][url=]B
channel 0.5V DC[/url] by
[url=]Graham
Butcher[/url], on Flickr
[url=][img][/img][/url][url=]A
channel 1V DC[/url] by
[url=]Graham
Butcher[/url], on Flickr
[url=][img][/img][/url][url=]A
channel 0.5V DC[/url] by
[url=]Graham
Butcher[/url], on Flickr
Thanks in advance for any help you can offer me.
Graham
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