View Single Post
  #3   Report Post  
Posted to
[email protected] is offline
external usenet poster
Posts: 177
Default Hoseki Digital LED Clock

On Nov 10, 8:43*am, Clueless wrote:
Hi all

I have a Hoseki Digital LED Alarm Clock Model H-5008 / 230VAC

The primary of the tiny transformer inside has gone open.

I have some similar transformers with me but I do not know what is the
output of the original transformer. There is no marking on the pcb
about the input voltage.

Is there any way to find out? Start at a low voltage with a variac
until the unit starts working?

Any help will be appreciated.

Thanks in advance


Look at the voltage ratings on the capacitors, then go down to about
1/2 of that for the secondary voltage of the transformer. Remember,
the peak voltage is 1.414 times the nominal voltage. So, for example,
if the capacitors were rated at 50V, I would try a transformer that
gave a rectified voltage of about 35 - 40 V DC, Divide the 40V DC by
1.414 to get a transformer that had an AC output of about 25 - 30 V ac.