Power problems on HP5372A
Fellow time-nuts,
The last couple of days I have been experiencing problems with my
HP5372A as it will not power up. I have noticed that my power switch is
cranky but haven't thought anything about it, just one of those annoying
personalities.
As everything else seems fine in the unit, I was suspecting the power
switch. It's just that it actually doesn't switch much power. It's a
low-power DC power enable switch. So just shorting it on the right side
enables the switching supplies and it "opens up".
So if one encounters similar behaviour on a HP5371A, HP5372A or HP5373A,
do have a look at the power switch signals. They are easy to access on
the back side of the front panel (fairly obvious three fairly neatly
soldered in).
I'm not sure I can find a suitable replacement. I will see if it is a
mechanical problem that can be overcome with some patience.
Anyway, the counter itself is intact.
Cheers,
Magnus
Suggest that you disconnect the switch and run 50-100 ma DC through the
contacts push on and off a number of times. This should clean them. Low
current such as you suggest may not effectively keep them clean over the
years. Did wonders on a SRS FS700 I have.
Regards
Paul
WB8TSL
On Tue, Dec 28, 2010 at 3:17 PM, Magnus Danielson <
magnus@rubidium.dyndns.org> wrote:
Fellow time-nuts,
The last couple of days I have been experiencing problems with my HP5372A
as it will not power up. I have noticed that my power switch is cranky but
haven't thought anything about it, just one of those annoying personalities.
As everything else seems fine in the unit, I was suspecting the power
switch. It's just that it actually doesn't switch much power. It's a
low-power DC power enable switch. So just shorting it on the right side
enables the switching supplies and it "opens up".
So if one encounters similar behaviour on a HP5371A, HP5372A or HP5373A, do
have a look at the power switch signals. They are easy to access on the back
side of the front panel (fairly obvious three fairly neatly soldered in).
I'm not sure I can find a suitable replacement. I will see if it is a
mechanical problem that can be overcome with some patience.
Anyway, the counter itself is intact.
Cheers,
Magnus
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Hi Paul,
On 12/29/2010 03:04 AM, paul swed wrote:
Suggest that you disconnect the switch and run 50-100 ma DC through the
contacts push on and off a number of times. This should clean them. Low
current such as you suggest may not effectively keep them clean over the
years. Did wonders on a SRS FS700 I have.
Hmm, will try. However, ohming it does not give much hope.
I now have a replacement switch in place which is kind of a ugly hack,
but it works. Thanks to thermoglue it also sits stable in the hole where
the old one used to be.
The trouble is that the switch action requires much more force than I am
used to. The new switch is distinct but does not require closing in to
physical violence.
I wonder if not the actual mechanics is broken such that it actually
does not even get there.
Cheers,
Magnus
Hard to say but if the switch is out take it apart and look.
Very very carefully some times there are little springs that hold the
contacts in place.
Anythings possible lubricant that has frozen up etc.
I hate hacks but sometimes you do not have a choice.
Gud Luc.
On Tue, Dec 28, 2010 at 10:48 PM, Magnus Danielson <
magnus@rubidium.dyndns.org> wrote:
Hi Paul,
On 12/29/2010 03:04 AM, paul swed wrote:
Suggest that you disconnect the switch and run 50-100 ma DC through the
contacts push on and off a number of times. This should clean them. Low
current such as you suggest may not effectively keep them clean over the
years. Did wonders on a SRS FS700 I have.
Hmm, will try. However, ohming it does not give much hope.
I now have a replacement switch in place which is kind of a ugly hack, but
it works. Thanks to thermoglue it also sits stable in the hole where the old
one used to be.
The trouble is that the switch action requires much more force than I am
used to. The new switch is distinct but does not require closing in to
physical violence.
I wonder if not the actual mechanics is broken such that it actually does
not even get there.
Cheers,
Magnus
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi Paul,
On 12/29/2010 05:00 AM, paul swed wrote:
Hard to say but if the switch is out take it apart and look.
Very very carefully some times there are little springs that hold the
contacts in place.
Anythings possible lubricant that has frozen up etc.
Highly suspect, but the small body size makes it difficult to go beyond
the removal of the plastic rocker. For post mortem analysis yes, but I
am sceptic about being able to put it back into service again. It would
not fall into my set of skills to do it properly.
I hate hacks but sometimes you do not have a choice.
Me too. At least I got this one down to "I can live with it, but it is
ugly" level. I.e. the wrong switched glued into location such that it is
mechanically stable and operateable. If I get a working replacement I
can install that.
Gud Luc.
Thanks.
Cheers,
Magnus