Hi Frits.
I've repaired a lot of B1's both JH and standard. Potentiometers in power part has always been bad on this controller. It is not a big issue to replace poti's but adjustment is a bit tricky. One is so sensitiv that you get the error you have, if it is just a few degrees out of adjustment. Send the controller to ATECH in germany or find your local ZAPI dealer and get a price. They know exactly how to adjust it and then you have some kind of gurantie.
Best regards, MAX
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