Scheppach Planer keeps blowin fuses - Help needed!

[markh]

Hi Guys,

Newbie here.. My Scheppach HS-2 Kombi (20 years ish old but not used much) keeps blowing 13 amp fuses. The motor is rated at 9.5 amps, but when I put a new 13amp fuse in the plug and turn the machine on, I get a low humming noise for a few seconds, then nothing. The motor does not turn. On button does nothing after this until I replace said fuse when the same thing happens again.

Any ideas? Could it be anything to do with cold & damp or does the old girl need a bit of TLC?

And another thing......... My 12 month old Record Power BS300 bandsaw will only work if I keep the on button on the NVR switch pressed all the time. As soon as I let go, it stops (ie it won't latch on).

Either I'm having a bad week or the cold is getting to both of them!!

Any help appreciated from any wiggly amp wizards out there!

Cheers,

Mark

 

[Scrums]

Hi

Just stopped using my Scheppach combi - I had to run that off a 16a 'Blue' plug - or alternatively to prevent your problem, what I started out with was a panel pin soldered across the fuse housing ....not to be advised, though effective.

Chris.

 

[jasonB]

Could well be the cold weather my kity can be a bit hard to start in the cold, turn the block over a couple of times by hand and see if that works. If not play a fan heater onto it or slacken the belt a bit.

Jason

 

[Carlow52]

mark,
Welcome to the forum, At least its warm in here!
Re the planer, I would take off the belt first and see if the motor will run, if so then its a voltage/amps start-up current issue.
(If not, depending on motor could be the condenser)

The planer block adds a lot of startup current load.

there is a sticky on these types of issue here by 9fingers, its also in his signature.
edit: here it is
https://www.ukworkshop.co.uk/forums...in-the-home-workshop-updated-iss2-t35143.html

 

[markh]

I was thinking about a 16 amp supply but I guess that means a dedicated supply from the fuseboard. I will also try running the motor with the belt disconnected. I have spun the block by hand and it seems free enough.

Next plan is to take the motor off and take it in to the house to dry out. It is not actually wet, but the garage is sub zero at the moment!

I was also wondering if I need a new starter for it which might not have such a power spike - any thoughts?

 

[9fingers]

Hi Mark,

I got your PM but will reply here just in case it helps others and will maybe remind them to be more specific to aid fault analysis

I need some more information please.

When you say it hums and then stops (humming?) is that when the fuse blows or does that happen later?

Is your machine fitted with electronic or mechanical braking system?

What is the power rating of the motor?

As far as your bandsaw problem goes, this sounds like you have mechanically operated, electromagnetic NVR starter as fitted to many modern lower power machines. There is a photo of one in my motor write up see figures 18 & 19. These have relatively low life expectancy and it sounds like it needs replacing. Axminster stock them.



Cheers

Bob

 

[jasonB]

Would also be useful to know if the machine started OK in the past as this would rule out start up load issues at normal temps

J

 

[markh]

Thanks for all the help so far gents. Not at home today but from memory the motor is rated at 1.5kw and does not have any kind of braking mechanism. The machine does start ok in warm weather but has blown fuses in the past. It always blows a fuse if I try to use any kind of extension lead but usually works fine plugged directly to a socket on the ring main. This suggests that it is drawing about 13amps at start up despite the motor being rated at 9.5amps. The humming lasts 2 or 3 seconds then stops when the fuse blows and the motor does not start to rotate. When I have had problems in the past, the motor has started to spin up before the fuse blows again suggesting it has always been near the limit for a 13 amp supply.

Regarding the bandsaw, it has only been used a couple of dozen times so I hope the nvr switch is not worn out already because it is conveniently just out of warranty!

 

[9fingers]

Your planer has two problems.

1) It should be run from a 16amp circuit and a type C 16amp breaker. This is because although the Motor current might be stated as 9.5 amps, the starting current is very much higher than that and due to a combination of spinning up a heavy cutter block to 3-4000 rpm, voltage drop on extension leads and stiffer belts in cold weather the time taken to start is longer and that is causing fuses that have a short term tolerance to overload, to blow when the overload is present for longer.

2) Of more concern is that the motor does not appear to even try to turn before the fuse fails. This indicates to me that the starting circuits in the motor have failed.
These break down to failure of the internal centrifugal switch or dust in the contacts OR, failure of the starting capacitor. These are possibly of similar probability. The last option that is pretty unlikely is the failure of the starter winding itself and that would mean motor replacement as re-winding is not likely to be an economic proposition for a 1.5kW motor.

Remove the belt, switch on and immediately spin the shaft. if the motor starts switch off and try and restart but spinning it in the opposite direction. If it will run happily in either direction without blowing the fuse then this suggests failure of the starting circuit as this defines the direction of rotation.

With the motor disconnected from the mains. Measure the DC resistance across the capacitor. If this is more than say 10-20 ohms, the either the starter winding is open circuit or the centrifugal switch, which should be closed , is open either due to failure or dust & dirt or the starter winding is open circuit. Strip down the motor and directly measure the starting winding. if this is open circuit replace motor or if it is intact, clean and /or refurbish the centrifugal switch.

If the resistance measured across the capacitor when connected to the motor is only a few ohms and yet the motor will still not start, then the capacitor should be disconnected and measured. It should be within +/- 10% or so of the marked value.
Fit a replacement if necessary - this should only cost you up to say 10 pounds and I can supply these if you like - up to you.

Hope this helps and please do report back with findings.

As for your bandsaw NVR - age is irrelevant. New components fail just as much as old ones do. It could be down to dirt and dust or component failure. These can sometimes be opened with care but other are glued together and irrepairable.
In this particular instance I do not suspect door interlocks, as if these are wired correctly it should not be possible to start the motor whilst pressing the start button at all. This rather undesirable action is indicative of the mechanically operated, magnetically latched NVRs that I referred to.
IME, bandsaws fitted with DOL NVR starter that fail to start, are nearly always due to safety interlock switches.

Good Luck

Bob

 

[markh]

Progress is being made! Just phoned Record Power and a new NVR switch is going in the post today - excellent service!

Regarding the planer, I need to replace the consumer unit in the workshop anyway, so I will get a dedicated 16 amp supply installed to run the machines. In the mean time I will check the motor as Bob has suggested.

Just found the owners handbook - bought it in 1983!!

Thanks again for all your help so far - I will let you know how I get on.

 

[markus]

hi, i have the steppach hms 260 that does the same thing. its strange because had it 10 years and it ran on the 13amp fuse it was bought with for years with out ever blowing the fuse? but it has just recently started blowing the fuse when starting up can not work it out???

 

[9fingers]

hi, i have the steppach hms 260 that does the same thing. its strange because had it 10 years and it ran on the 13amp fuse it was bought with for years with out ever blowing the fuse? but it has just recently started blowing the fuse when starting up can not work it out???

Maybe if you read the thread, you will be able to work it out?

Bob

 

[markh]

I have managed to get the motor running by disconnecting the drive belts and spinning the motor by hand before the fuse blows and it runs happlily in either direction.....

Next question is do I replace the capacitor before I start pulling the motor apart to check wiggly amp type stuff? (Don't have a multimeter and wouldn't know what to do with it if I had one!!)

If I replace the capacitor (might take you up on the offer, Bob) and it works, problem solved and I can return to the business of turning half an oak tree in to nice flat boards. If it doesn't, it's off to B&Q for a multimeter and start dismantling the motor to clean things and hope it fixes it!

If I do get a rush of blood to the head and start dismantling the motor, how do I identify the starter winding and the contacts that need cleaning?

I have read through your excellent article, Bob but electrics is a subject that it fairly well down my list of strong points! I am confident with all things mechanical, so I will be happy to clean up the contacts and refurbish the switch as you have suggested but I need to know what I am looking for.

Cheers,

Mark

 

[9fingers]

OK - that is progress.

Given you don't have a meter or experience in using one, could you borrow one from someone who does know what to do with one perhaps?

Or you could start with replacing the capacitor but you might still have to open the motor to get to release the connections.

The centrifugal switch will be obvious once you open the motor and the start winding is the one connected to the starter switch.

If you are not confident with the whole analysis, dismantling and repair exercise then you could send me the motor and I'll sort it out if you like? I'll only charge you cost of any materials - I don't do this for a profit - just for fun.

Let me know what you reckon.

Bob
Courier charges (parcel 2 go) are about £8 each way inc vat from memory

 

[kirkpoore1]

Mark, Bob has this one nailed--bad capacitor or something else wrong with the starting circuit. This is an excellent learning opportunity for you if you're anywhere near Bob--save the shipping money and take the motor to him yourself so you can watch him fix it. Motors aren't that hard to work on, though the first one is kind of scary.

The only other suggestion I have is to change the bearings while you have the motor apart. At 27 years old, their best days are behind them. They may last a few more years, but they'll probably go when it's least convenient for you.

Kirk

 

[9fingers]

Mark, Bob has this one nailed--bad capacitor or something else wrong with the starting circuit. This is an excellent learning opportunity for you if you're anywhere near Bob--save the shipping money and take the motor to him yourself so you can watch him fix it. Motors aren't that hard to work on, though the first one is kind of scary.

The only other suggestion I have is to change the bearings while you have the motor apart. At 27 years old, their best days are behind them. They may last a few more years, but they'll probably go when it's least convenient for you.

Kirk

That would be a good option Kirk. It is the best way of learning - to have someone show you how! The OP has not filled their profile in with a location so I can't tell how easy it would be to get to me. The only possible snag is that if I don't have the right capacitor in stock, my supplier operates by post and it would be 2 days to get one. Same for bearings.
If you fancy a trip to the Southampton area then you would be more than welcome to visit.

Bob

 

[markh]

That is a very generous offer Bob! I live near Hemel Hempstead so Southampton is a bit of a trek. I am happy to give it a go myself. I will get a multimeter - handy to have anyway - and check the starter circuit. I can always post some photos here if I get stuck!

Replacing the bearings sounds like a good plan whilst I am at it and the old girl needs some new drive belts so it sounds like I am starting a new project but there is nothing worse than a planer letting you down when you need it now!

Any advice on suppliers for capacitors, bearings & belts?

Many thanks again for advice & encouragement!

 

[9fingers]

Hi Mark,

Yes more than happy to try and talk you though any difficulties you might incur. Make diagrams and take notes about connections. Photos are good documentation as well as written notes. Colours of wires are NOT standard and I can't tell the number of queries I get along the lines of " my motor has N terminals. Which one should the yellow wire be connected to?"
HTF should I know ! :lol:

Bearings:
try Arc Euro, Bearing boys,RS
Belts:
try Bearing boys,RS
Capacitors:
Farnell, CPC, RS, Maplin - although postage can be a bit of a killer on small orders

I can supply RS stuff post free as I have an account and will pass on discounts too.

You might also find local bearing, belt and capacitor suppliers lurking in small industrial units near you.

When you look at multimeters, then consider ones with a capacitance range as these can be handy for checking capacitor values. They might well be a little more but useful for this sort of work. It is not worth paying a huge amount for a meter as you don't want the last word (or digit!) in accuracy.

HTH

Bob

 

[kirkpoore1]

Mark:

Here's a page with pictures showing motor disassembly and cleaning up centrifugal switch contacts. This may come in handy if the capacitor isn't the only problem. When you pull it apart, make sure you take pictures, and note the location and order of any spacers or washers on the motor shaft.

http://wiki.owwm.com/Baldor Motor Repair.ashx

Kirk

 

[9fingers]

Excellent link Kirk! thanks I'll bookmark that for future referals

Bob