strange timer fault

[Little Monster]

Hi all, wonder if anyone can suggest what is going on here.

I have a couple of electronic time switches, nice range of settings they
have too They use an internal battery to keep time when the mains
fails.

Funny thing happened; within a month of each other (at about guarantee
ending time), they started losing time very badly - almost an hour a day
eventually. Unplugged them both, left them to one side, set the time
correctly to have a look just how bad the drift was, where I could see
them properly. Funny thing happened, they both started keeping good time
again!

Looking inside, the clock board has 3 ceramic caps, a crystal and chip
epoxy bonded to the board. Small rechargeable battery feeds into it. I
think either the ceramic caps are rated a bit too close to the battery
voltage and leaking a bit when at charging voltage, but okay on battery
only.. or something odd is happening with the battery or it's charging
circuit. Not done any tests yet (not that important to fix). Guessing
the former, I could just connect a resistor in the clock supply to take
the voltage down a bit, but any suggestions as to what might be the cause
of the fault - probably too subtle for me!

Monster
--
I am the sexiest man in the UuuuKaaaayy
All the girls love me
And I will never grow Ooollldd
I am the sexiest man in the UuuKaaaay!

http://www.the-monstruum.co.uk

 

[WEBPA]

Hi all, wonder if anyone can suggest what is going on here.

I have a couple of electronic time switches, nice range of settings they
have too They use an internal battery to keep time when the mains
fails.

Funny thing happened; within a month of each other (at about guarantee
ending time), they started losing time very badly - almost an hour a day
eventually. Unplugged them both, left them to one side, set the time
correctly to have a look just how bad the drift was, where I could see
them properly. Funny thing happened, they both started keeping good time
again!

Looking inside, the clock board has 3 ceramic caps, a crystal and chip
epoxy bonded to the board. Small rechargeable battery feeds into it. I
think either the ceramic caps are rated a bit too close to the battery
voltage and leaking a bit when at charging voltage, but okay on battery
only.. or something odd is happening with the battery or it's charging
circuit. Not done any tests yet (not that important to fix). Guessing
the former, I could just connect a resistor in the clock supply to take
the voltage down a bit, but any suggestions as to what might be the cause
of the fault - probably too subtle for me!

Monster
--

I think you are making this waaaay to hard. Unsolder and replace the battery
cell (making certain you have correctly identified the cell). Close and use.
Rationale: The cell is going to fail years before the capacitors.

webpa

 

[Sir Charles W. Shults III]

"Little Monster" <root@localhost.localdomain> wrote in message
news:7fcefa7478dd3b2d4776ef617ca22058@news.teranews.com...

Hi all, wonder if anyone can suggest what is going on here.

I have a couple of electronic time switches, nice range of settings they
have too They use an internal battery to keep time when the mains
fails.

snip

Model numbers? Manufacturers? Those would be helpful.

Cheers!

Sir Charles W. Shults III

 

[Little Monster]

On Mon, 07 Jun 2004 02:12:13 +0000, the world was enlightented by Sir
Charles W. Shults III, unto whom the words are attributed:

"Little Monster" <root@localhost.localdomain> wrote in message
news:7fcefa7478dd3b2d4776ef617ca22058@news.teranews.com...
Hi all, wonder if anyone can suggest what is going on here.

I have a couple of electronic time switches, nice range of settings they
have too They use an internal battery to keep time when the mains
fails.

snip

Model numbers? Manufacturers? Those would be helpful.

Beg your pardon Sir, I thought these things were pretty generic...

Micromark model MM9539, 230V 50Hz 13A, both have batch number 193370/0122

Thanks for the response

Monster
--
I am the sexiest man in the UuuuKaaaayy
All the girls love me
And I will never grow Ooollldd
I am the sexiest man in the UuuKaaaay!

http://www.the-monstruum.co.uk