scroll saw blowing fuses

[jack sidebotham]

hi all,l have a brand new scroll saw with a serious appetite for fuses,it is SD1600V with a variable speed control and originally came from ALDI,though it is actually made in china and is sold under various brand names,main one being sheppach in Germany,it has a fuse holder mounted in the front panel just under the variable speed knob,and is fitted with a 5 amp glass fuse as stahdard,it also has a nvr switch,problem is, the fuse blows instantly on switching on at the socket,l have tried repositioning the speed knob but this has no effect,l cannot locate a wiring diagram anywhere,but l do question the fitting of a 5 amp fuse,l am sure it must draw more than that,having closely inspected the circuit board everything seems fine,but there must be a short somewhere,l am reluctant to try a higher fuse rating,as if there is a short,l will only cause further damage,an idea l had was to bypass the speed control and settle for on/off only,by running the mains feed to the IN side of the switch,and connecting the motor direct to the OUT side of the switch,bypassing the circuit board/speed control/fuse carrier completely,any help will be more than welcome!!!!!

 

[Tha fios agaibh]

The 5amp fuse sounds reasonable as it's only rated at 120watts.
Make sure it doesn't require a time delay fuse (and you might be using a fast acting fuse), but Yes, it sounds like a short. You could disconnect the motor and check the resistance of the windings.

You could also see if it blows fuses with the motor leads disconnected, which would point to the speed controller as the problem.

It could also be that the blade tension or mechanical force is overloading the motor.

 

[kellys_eye]

Three year warranty on Aldi stuff - you could take it back....

 

[jack sidebotham]

thanks for the response guys,l confess l don't know a lot about electrics,been looking at it again,l am now wondering if it is wired up right,the pc board has a row of spade terminals at one endmarked:-mot +/mot-/grnd/n/L......following the wires gave me cause to wonder if they are in fact connected up correctly,the fuse seems to be in the neutral line,which seems odd to me,the NVR switch has 4 terminals on the back,2 marked IN and two marked OUT,but no indication as to positive/negative,is there anyone out there in the Chepstow area that might be willing to sort this out for me before l blow myself up???,beer vouchers will be forth coming!!!

 

[Tha fios agaibh]

Post some pictures of the pcb and wiring. Perhaps we can help without costing you beer vouchers?
On this side of the pond, its illegal to fuse the neutral (intentionally grounded) line. It wouldn't change your circuit operation, but could present a safety concern.

How long does it go without blowing fuses? Have you verified you are using correct fuse?
Does the motor shaft move freely and smoothly? Any motor will blow fuses if its mechanically overloaded.