DIYbanter - View Single Post - FA: Sencore LC53 Z Meter with Probe and AC Cord # 260388540185

Michael A. Terrell

JP wrote:

On 8 Apr 2009 10:36:27 -0400, (Scott Dorsey) wrote:

JP wrote:
According to the manual it reforms caps.That's my best answer.So where
is the drawing ro schematic of what you are talking about since I am
selling this one?

It does, but it's not a really good way to reform caps.

Here is a schematic, though you must have a fixed-width font to see it:

+-----)(--------+
| YOUR CAP |
| |
| o--------)-------+
| / \ | |
+--o/+ -\o----+ |
\ / |
\ / 1kv bridge |
o 1K ohm
| or more
| 1W or so
| 115vac .2a |
+uuuuuuuuuuuuuuuu+
==================
+mmmmmmmmmmm+-------------------/ |=
| on off ( |
+-------------------o/ o--------\_l= 117vac

The transformer output should be maybe half to 3/4 the rated voltage on the
capacitor. This is really just the front end of a power supply with an
enormously high value current limiting resistor so that the cap gets charged
up much more slowly than it normally would in a power supply application.

You can put a load shunt resistor across the cap if you want it to charge up
even more slowly and if you want to reduce the maximum voltage it charges up
to.

You can alternatively take the attitude that if a cap needs to be reformed
it should probably be replaced instead.
--scott
The manual states that the Sencore uses very low amperage to reform
caps...maybe micro amps IIRC...don't see the difference except that it
adjusts with a switchinstead of having to swap out components and
rebuild a power supply for each value...and has a readout to show you
when the caps is "done" ...just my 2 cents...

Keep digging a hole. The basic circuit shown is just one way to
reform electrolytics. A better circuit uses a Variac before the
transformer to let you set it anywhere you want it, and use a resistor
to limit the current to the desired range. A mA or uA meter in series
with the negative lead to monitor the current. its been done that way
from the first days of manufacturing electrolytics.

BTW, have you ever USED the Sencore LCR bridge for actual work? I
have. I have also used HP. The only 'feature' the Sencore meter had
was the ability to measure ESR. You can buy a kit to do the same thing
for about $60, or 'roll your own' for $5.

--
And another motherboard bites the dust!