HP 8640B Quits after 15 Seconds

M

MPalmquist

Guest
8640B Signal Generator (001, 003) starts up fine for 15 seconds, then
display goes blank and RF output ceases. +5.2 LED goes out, indicating
current foldback is activated to shut down supply.
I can hear a "tick" at the moment it quits, as if a small relay is operated
or released. After a minute or so it starts
up for a second or two, then quits again. Sound familiar to anyone?
Something appears to be slowly
pulling down the 5V supply. Swapped out all the easily swappable cards from
working unit with no solution. Swapped out the counter module with same
result.Unit did stay powered up with the counter module completely removed,
but symptom reappeared when backup counter module was installed. Replaced
+5.2 Filter Cap no change. Replaced Regulator Transistor no change.

Any suggestions greatly appreciated.

Mark in Atlanta

--
 
On Tue, 30 Mar 2004 01:00:05 GMT "MPalmquist" <jmpalm@mindspring.com>
wrote in Message id:
<pE3ac.5107$yN6.1280@newsread2.news.atl.earthlink.net>:

8640B Signal Generator (001, 003) starts up fine for 15 seconds, then
display goes blank and RF output ceases. +5.2 LED goes out, indicating
current foldback is activated to shut down supply.
I can hear a "tick" at the moment it quits, as if a small relay is operated
or released. After a minute or so it starts
up for a second or two, then quits again. Sound familiar to anyone?
Something appears to be slowly
pulling down the 5V supply. Swapped out all the easily swappable cards from
working unit with no solution. Swapped out the counter module with same
result.Unit did stay powered up with the counter module completely removed,
but symptom reappeared when backup counter module was installed. Replaced
+5.2 Filter Cap no change. Replaced Regulator Transistor no change.

Any suggestions greatly appreciated.
If you don't already have a service manual, these guys have a
downloadable one - just sign up for the free manual service:
http://www.teknetelectronics.com
 
JW

Thanks. The manual is also posted on BAMA bama.sbc.edu. The
teknetelectronics site looks like a good one to bookmark.

Mark


--
If you don't already have a service manual, these guys have a
downloadable one - just sign up for the free manual service:
http://www.teknetelectronics.com
 

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