Hello i am looking at a Grundfos Scala2 pump
i did download a 16 page service manual with no circuit
I have ordered from Digikey and Fitted FSQ500L
Which seems to be running But not right
i do not have a circuit so just going by IC data sheet
this does not have a opto coupler
The ic runs at 100khz for about 150us then stops waits about 1ms then runs again
i have checked the ESR of caps ok
the secondary has 5uf on both sides of 3 terminal regulator
this powers the micro and sensors which draw about 11ma
if i add 47uf to this the pump will power up and run
can anyone help before i try and draw the circuit of primary
I have attached a image from scope yellow is D, blue is FB, on FSQ500L
FB is connected to 6legged smd with 1F then Y on its side (what is this device)
Vcc on FSQ is clean 8v,
there is 2 opto couplers used between hot and cold side,
i don't see any opto used for feedback
in data sheet "if FB reaches 4.5v then shuts down" i don't think applies
thanks for reading