No DC motor control
15V and Sig LEDs on but no Gate or HV bus LED.
Bit of a chicken and egg situation.
5V supply also ok
Mains side uses a pair of SCRs driven by a triac opto that has its
driving internal LED biased off, to provide the power DC as distinct
from minor supply that is present.
Main control is some custom uC.
DC side uses a powerFET to control the motor .
It seems that if there is no gate signal to the MOC opto so there is not
any rectified HV dc for the powerFET , or could the Power|FET be non
functional to some low power test setup and the uC locks out.
Will remove the powerFET and check out of circuit , but at this stage
that seems the limit of any further fault finding. Even applying some
sort DC I asume the uC will lock out anyway, or the uC is corrupt of
course, either way no further forward

Surely if exercise machines were designed properly, the person using
them would be powering the electronics

On 05/11/2013 16:24, Nelson wrote:
On Tue, 5 Nov 2013 09:37:01 -0500, N_Cook wrote
(in article ):

Main control is some custom uC

You can sometimes find salvaged/repair parts on the net. I have a
Precor Elliptical Trainer with similar problems. The custom IC's are
hard to get around especially with no schematics. Good luck.

I am toying with the idea of building my own replacement controller
using a Raspberry Pi or Arduino. I'm thinking I can work backward from
the discrete components and perhaps build an even better controller.
But it's no quick fix


removed the powerFET and solid 25 ohm gate to s/d , tried a lower rating
one but the driving sense amplier may have been knocked out, other than
14V supply to it, no further forward, at least referenced to 0V so
scopeable , but I suspect the uC has "fingers" in all directions