VFD damage?

[Cornish JackParticipant @cornishjack]

The photo below is of the control box facia of the VFD fitted to my ML7. As can be seen, the speed control knob has broken off and I'm somewhat puzzled by the internal 'remains'. I ha d expected to see a spigot of sorts which the rotary knob would have plugged on to but there seems to be only a metal 'wiper' . I'm still able to vary speed with a pendant control but can anyone suggest a simple remedial 'fix' – the original knob has been smuggled away by the workshop gremlins!!

rgds

Bill

[Cornish JackParticipant @cornishjack]

[Nick HulmeParticipant @nickhulme30114]

if you knock the shaft off some potentiometers they will show their guts

it won't affect the use of an external pot.

[Mike PooleParticipant @mikepoole82104]

The pot may be a skeleton type trim pot that can have a knob that click fits into the wiper, I would not think it’s a good application for a trim pot as they are not really made for high usage applications.

Mike

[John RuddParticipant @johnrudd16576]

Put a sticking plaster over the injury and carry on as if nothing happened…..

If you are using an external pot for speed control, the injury sustained will have no lasting effect unless there's a regression to panel control… would require further medical intervention which involves selective programming..

Edited By John Rudd on 20/08/2018 19:22:13

[Howard LewisParticipant @howardlewis46836]

If you feel sufficiently confident, (or know someone who is) you could remove the control box cover and see what the original pot was, (Its value and Logarithmic or Linear, It is then merely a matter of obtaining a replacement and soldering in place of the damaged one. The supplier of the pot should also have a selection of knobs which will suit (RS or Farnell would be good starting points)

Then you should be back in business!

Howard

[MuzzerParticipant @muzzer]

Log or linear??? It's a speed control where the voltage sets the speed, so hardly going to be log.

Although it's badged as an Omron, it's actually a Yaskawa.

Best take the cover / back off if you are bothered enough to want to fix it. You might then be able to bodge an replacement pot in place of the original. The value won't be critical as long as it's between something like 5k and 50k – consult the manual for the approved range of pendant pot values to be sure, as it's almost certainly using the same reference voltage.

Murray

[Cornish JackParticipant @cornishjack]

Many thanks for all of your suggestions etc. I'm strongly inclined towards doing nowt as wiggly amps are a major mystery. I have taken the fascia panel off and the item underneath is not like any pot I have seen previously – more like a thin 'wiper' strip. With the pendant functioning and it being a TriLeva 7, speed control shouldn't be a problem, so I shall 'observe from deep cover'

rgds

Bill

[Author]

Posts