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Looking for recomendations.

I need a repair doing

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David Richardson 318/10/2020 16:48:26
4 forum posts
1 photos

Afternoon all.

Hope everyone is well. (especially in these weird times) I'm not sure of its just me but now more than ever i'm so tempted to retreat into the shed and stay there untill Covid buggers off.

one problem however.

i have a clarke CL250m and the overload light is on. its had a new circuit board and the motor is fine. i think ive bench tested all of he switches and wires in there for continuity etc, but it still wont run. I'm at the limit of my technical knowledge WRT this. I'm based just outside of manchester at the moment; and wondered if anyone knows of any repair shops out there who could look at this for me? ive tried googling "tool repairs" etc but not had much look.

\i'd be greatfull for any recomendations that any of you fine people have.

Thanks in advance


John Rudd18/10/2020 17:10:13
1452 forum posts
10 photos


A bit more info please....

What model speed controller is it? For a CL250 its likely to be an FC250, can you confirm model number plz.

How was the motor tested? Ideally it should be bench tested on a DC power supply and run up to its max speed. Any arcing/sparking at the commutator needs to be checked.....Shorted comm segments/worn brushes etc...

Has the speed pot switch been tested? The contacts on the rear should close at minimum speed ( turned fully anti clockwise to off )  and be open at any other pot setting.

Edited By John Rudd on 18/10/2020 17:11:05

David Richardson 319/10/2020 13:01:16
4 forum posts
1 photos

Good Afternoon John.

thanks for the reply. I'll try to answer as best as i can; but as mentioned i'm getting near the limits of my electrical knowledge. the lathe has a SIEG-FC150BJSMD board in it; and that's new.

The Motor, was tested on a friends DC power supply, it span up and the brushes are good (not new but they still have life in them) we tested the other motor on the Mill as well and that was good as well.

regarding your questions about the other switches; they havent been tested but i'm not really sure how to to be honest, which is why i was thinking its about time to send it out to someone who knows what theyre doing,



John Rudd19/10/2020 13:17:43
1452 forum posts
10 photos


The switches need checking with a dvm on its Ohms ranges or with a continuity tester....( battery bulb and bits of wire should suffice....)

Manchester is a bit far for me...(Newcastle...) otherwise I'd look at it for you...

Test the switches then come back and we'll go from there..

An Other19/10/2020 14:41:06
257 forum posts
1 photos

Hello, David,

So far you only seem to have concentrated on the motor, and you seem to have confirmed that it is OK. You can test the control board by connecting a 100W filament type light bulb in place of the motor. When you you turn the speed control, the brilliance should change. If it remains at full brilliance, or is off, then the chances are that the output devices on the control board are defective (I call them devices, because no-one on this forum, as usual, seems to agree what they are - to me, they are power MOSFETS. On most of the FC250 boards I have repaired they have been either 2SK790's or IRLZ44N. The 2SK790 seems to be fitted to older boards, and the IRLZ44N to the newer boards - they can still be obtained. I am not sure which devices(s) are used on the board you have - there are many versions of these controllers, but in general the output devices have been the same whatever the board.

John Rudd19/10/2020 14:52:45
1452 forum posts
10 photos

While I do not profess to be an expert in repairing the electronics for mini mills/lathes and larger DC motored machines, I am comfortable with the experience and knowledge I have in expediting repairs...


Even though the replacement board is new, until the wiring/switches etc test out ok and the 'overload lamp' issue is resolved, the board test at the moment will not work.....

Edited By John Rudd on 19/10/2020 14:58:55

An Other19/10/2020 17:36:43
257 forum posts
1 photos

I was going to reply to the last post - but there really seems no point.

Thomas Cooksley19/10/2020 18:34:03
55 forum posts

Hi everyone, just a thought: it's not something simple like the chuck guard not being closed? or if the motor runs OK on the bench is the lathe seized or tight to turn? Tom

Samsaranda19/10/2020 19:07:59
1396 forum posts
5 photos

On my Warco lathe I once had a problem with the chuck guard, the micro switch was not operating, it Had moved slightly and this stopped it operating correctly, once adjusted normal service was resumed and has worked every time in the years since then.
Dave W

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