On 20 Feb 2006 21:58:41 -0800, "Goldenshuttle"
put finger to keyboard and composed:

Ok guys, here is a worthwile task
I ve been repairing treadmill for years.
One common repair is 2 replace a Morot controller ( known as Lower
board).

Normally, this board is iether SCR or PWM speed contoller for a 95-110
volt DC motor.
In many times it also feeds the elevation motor, which is a small AC
motor with a gear box.

When this lower board stops working, mostly it does not feed the DV
motor anymore, and sometimes the incline motor is still fed.

Companies who make Treadmills never reveal how 2 repair these board
(ALTHOUGH) some of them sell refurbished boards.

Lowers boards sell between 120 - 550 $ depending on make and model.

Output stage on these boards consist of abnd SCR, MOSFET and a bridge
diode.
Can anyone suggest a way 2 repair such boards.??
plz advise

Thanks
Samy Goldenshuttle
TORONTO

I've repaired boards for other equipment that uses MOSFET controlled
DC motors, eg floor scrubbers and scooters. The usual fault is blown
output devices. All that is required is replacement of the MOSFETs and
associated components (eg zeners and diodes), and possibly the smaller
transistors in the previous stage. Of course you will need to check
the motors for worn brushes, etc. When choosing a suitable replacement
MOSFET, pick the one that has the lowest Rdson. That will minimise its
heat dissipation.

- Franc Zabkar
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