Friday, 19 August 2011

First you get "Check if thread is entangled. Check if needle is bent"...

.... and then the machine won't embroider. You do indeed "Check if thread is entangled. Check if needle is bent" but everything seems ok. So, what's the problem?

In short, the motor has blown. Specficially, the two induction coils on the PCB attached to the motor. In this picture they are the little brown capsules with stripes:

On your motor the coils are most likely green (but with the same pattern of stripes indicating 10 microhenries).

So, why does this happen and can it be fixed?

Well, I have nothing more than a theory at the moment but a couple of points are without doubt. First, the induction coils don't simply wear out. In other words, something caused them to go pop. The coils can be replaced by soldering two fresh ones on the board but without something else, they are likely to go pop again. Second, and almost certainly, the resistance across the main terminals of the motor will be far less than the figure of 400 - 800ohms specified in the Brother Service Manual. My theory, at present, is that with wear the resistance in the motor reduces which causes some sort of spike in the power going to the motor and this fries the coils. If this has happened (and it or something has happened in three of my machines), simply replacing the coils (about 10p) or fitting a new motor (about £65) will not sort the problem. Alas, a new power board will also be required (about £160).

For more on this please take a look at the tutorial on Main Board, power board and motor removal.

Quick update that I've been meaning to put on here for a while - if you get the "Check if thread is entangled. Check if needle is bent" message but your bobbin winder is still working, then your motor (and main board) are fine. You just need to look a bit closer at your machine as the chances are your thread is entangled or your needle is bent..... or the magic eye on the main shaft has failed....