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

JP[_2_]

On Wed, 8 Apr 2009 21:23:21 -0700 (PDT),
wrote:

On Apr 8, 9:36*am, (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. *

Caps must be formed once when new and then reform themselves
continually in use. Many lytics five or ten years old work great for a
decade or two if properly reformed. All you need is a high value
resistance in series basically.

I hate ASCII schematics but if you can't picture a standard half wave
or bridge rectifier off a secondary and a resistor you are in the
wrong business. I like to mount a salvage plate and filament
transformer-ones out of TV shops for old color TVs, bad for audio
because the B+ is too high and not enough current, are fine-in a dead
PC power supply metal box with a rectifier and jacks before and after
for DC or AC. You can put a filter cap inside the box after the
rectifier. Use with a Variac for convenient use. Add a series socket
for lightbulb current limiting and a shorting switch to taste, but
always a fuse on the primary.
Sencore manual says using bridge for measuring isn't right way for DC
measurements...I am assuning they know what they are talking
about...there's a LC102 manual on BAMA...might want to check it out
just for the fun of it..