Looking for ideas on this one,
maybe someone has had this fault before ?

in test mode Bigfoot will run CCW normal.

when CW engaged he will still run CCW but very, very slowly.

the opto and position tests are ok.

I have removed and checked the bi directional motor PCB for dry joints etc
all appears ok.

looking for tips on how to isolate motor PCB or power driver PCB at fault ?

Voltages at motor are 11v on red 2v on white CCW
11v on white and 11v on red CW

The only clue I have is that Bigfoot recently started running very sluggish in CW direction.
then the error started to occur.

I have stripped down mechanics, motor and gearbox check ok.

Appreciate any ideas

Cheers,
Ando

Thanks Skyemont !

I did not know that Mike made these

I would like to figure out how to isolate the problem still

Cheers,
Ando

Well you were correct Skyemont

it turned out the problem was the Bi Directional PCB,

I had spare time , so I decided to pursue

on closer investigation, I noticed some black spots on the tracks around
C2 the 100uf 35v electro (marked as C1 on the schematic)

these black spots on the tracks indicate leaking electrolyte
this corrodes the tracks.
sorry I did not take a before photo,

so I replace the cap and fix up the tracks
still the same : (

turns out that the track under pin 1 the output of U1 the comparator I.C
was high resistance 220 ohms to its destination the base of Q3

pin 1 is the big solder blob,
the work looks a little ugly
but works

one Happy Bigfoot now !

I suspect that leaky cap is very common on these PCB's

it is great that Mike is making a replacement PCB
his boards a built to a very high standard
had I not been bored and curious I would have purchased one

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