Hi Mike,
Thanks for the info on the FET -- I didn't know what it was for sure.
I understand that there is a more rugged FET which can be used for a
replacement so I'll talk to Homier about that when they call.
Like you, I found the controller worked nicely (until it failed).
I've stalled it several times at low speeds (parting mostly) and it
just hums -- I quickly turn it off with the pot and release the tool.
Since my lathe is inactive anyway I'm taking advantage of the down
time to fiddle with some of the suggested mods. I've lapped the
gibs/dovetails on the cross and compound slides and they seem a bit
smoother now although they were not bad to begin with. Now I'm
trying to adjust the backlash out of the cross slide without causing
binding, which isn't as easy as I expected...
John
--- In 7x12minilathe@..., "Mike Nash"
<mnfwd2.minilathe@m...> wrote:
It sounds like you have the newer (Sieg made) Homier with a mosfet
type
controller. I have the older Homier with the SCR controller and
these would
fail to zero speed with blown fuses.
Yep, it's a mosfet controller:
Description:
2SK 790
N-FET/500V/15A/150W
I find these failures strange. My Homier mini mill uses a mosfet
drive and
(so far) it has simply "tripped" when overloaded. Turning the speed
pot to
zero (click) and back on resets it.
Mike Nash
----- Original Message -----
From: "John" <moran03@e...>
To: <7x12minilathe@...>
Sent: Sunday, March 23, 2003 10:32 AM
Subject: [7x12minilathe] 7x12 Blows Fuses ?
My 7x12 which is now 2.5 months old popped its fuse shortly after
startup Friday, just as I was beginning a parting cut at low
speed.
I installed the replacement fuse and , with the speed control in
the
OFF position and the tool backed away, the lathe started as if it
was
at full speed and the fuse popped again in less than a second.
This is a relatively new unit so I called Homier and they
promised to
call me back on Monday. I'm just wondering if this is a common
problem; my understanding is the Homiers use an SCR based
controller
which is less prone to failure than the MOSFET types. My ckt board
has a sticker with FC250J/110V and the large power devices are
identified as K790 -- the board uses surface mount devices except
for power handling which are thru-hole. Anybody have more info
on
the Homier controller?
Up until this happened I was very happy with the controller since
it
allowed speed to be reduced to 12rpm, slower than most references
in
the 7x10 group specify. I did notice that when the speed control
was
in the OFF position that rotating the knob slightly(as alowed
while
OFF) made the chuck would move slightly and groan a bit. Since it
seems to be live even while OFF I always turn the wall outlet off
after use.
John
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