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--- On Sun, 10/5/08, Stephen Smith <sjsmith@...> wrote:

From: Stephen Smith <sjsmith@...>
Subject: [TekScopes] Re: TDS540 - replaced caps but beeper stuck on and clock issue?
To: TekScopes@...
Date: Sunday, October 5, 2008, 10:34 PM






Hello David,

I'm fairly sure that all the original TDS520/540/620/ 640/820 series do
not have battery backed real-time clocks. The time is kept in
non-volatile memory but not updated while powered down. You need to
set the time each time you power up. (I know, I have to do this on my
TDS820).

The TDS500/600/700 A,B,C and D series had battery backed RTCs.

Another issue is that the internal batteries in the non-volatile
components are eventually going to fail. They are supposed to have a
life of around 10+ years, however I think a lot of these are now well
over this. Do you know what the date code is on the DS1245Y-120?

As for the piezo beeper, I'm not sure, however it is on the front
panel PCB which you haven't done yet...

Regards,
Stephen.

--- In TekScopes@yahoogrou ps.com, David Woodhead <david_woodhead@ ...>
wrote:

Hi all,

I just finished replacing all the electroytic caps on CPU and

Acquisitions boards in my TDS540 (did not do front panel yet). I also
replaced a couple of TL074's that had a bunch of electrolyte
underneath them.

It now powers up and reliably passes the power on self test. I ran

the I/O cal routine and it calibrated without issue as well. In fact I
have checked everything I can think of and it all appears to be
working very well except.....

The beeper stays on continually. Also, the clock is not working

correctly. I can set and it runs fine but when I power down and power
up again (a few minutes later) it appears that the clock did not
continue to run when powered down. It does not default to year ~2002
(build date) - it remembers the time when powered down and picks up
where it left off when powered up again! When I press diplay time it
tells me that the clock is not updating when powered downand to run
the setup utility to set the time.

The scope is remembering time and appears to be storing calibration

values ok (when powered down). But the clock does not continue to run
when powered down and the beeper is stuck on.

Any ideas?

Thanks!
David.






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