Polisher repair?

alahol2

alahol2

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Portchester, Solent
www.troppo.co.uk
While I'm stuck in the house, I have a meguiars G220 V2 DA polisher which has bitten the dust. I suspect the variable speed electronics module has died.
I know very little about how this thing works electrically... I am looking at any way to get it going again.

The 240V lead (2 wire) comes into a switch. From the switch 2 wires go to the speed module. (There is a 0.3uF capacitor across the 2 leads, presumably for radiation suppression.) From the speed module 2 wires disappear into the body of the machine, presumably to the brushes etc.

Can I just bypass the speed module ie take the output from the switch and connect to the wires leading into the motor? Would that run it at full speed? Maybe I can use an external speed controller such as... https://www.ebay.co.uk/itm/2000W-SCR-Dimmer-240V-AC-Voltage-Regulator-Heater-1000W-25A-Fan-Speed-Control/292181746872?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

Or will I blow the whole thing up and/or electrocute myself?

PS spares are not available.
 
While not committing myself to say a definate "Yes, it's OK", I have a Bosch variable speed orbital sander and the variability of it stopped working. So I did the same as you're suggesting and it has worked well over the last 3 or 4 years. So as long as you're careful it'll be fine.
Mike
 
Had similar with a Kestral polisher. Managed to pretty much directly replace the variable speed part with a bit from the Makita spare parts catalog. Still going strong.

I suspect it'll be too lively if you were to wire it in with no speed control!
 
Thanks vegable and matthew
Just wanted to know that I wasn't doing something thoroughly stupid. At least I can now test if the motor works when I bypass the speed controller. If it's too fast, I can then look for a way to slow it down.
If I get anywhere I'll post again.
Cheers
 
If you have a multi-meter set it to AC and a range above 250V.

Do you have power at the leads as they come in?

If so then measure if you have power on the wires coming out of the speed controller.

If no power coming in then fuse or lead is at fault.
If power before and not after then controller at fault.
If power after controller then most likely brushes at fault.

IIRC they came with a spare set.

HTH.
 
Thanks for the suggestions...
Brushes seem OK, probably only about a millimetre worn away.
I've checked the leads and fuse for continuity. Again, they seem OK. Tried stretching and wiggling etc.

When it comes to 240V electricity I'm a wimp. I won't be playing around trying to measure voltages on exposed wires.
I prefer to wire it up as suggested, put the covers on and see if it works. If it doesn't then I'll have to see if I can get deeper into the machine to investigate further.

The rest of the casing, covering the actual motor and gearbox, is one of those ingenious magic boxes that needs a fairy key to get into. There are no screws, hidden or otherwise, and yet the casing is rock solid. If I do need to go further in I'll probably have to dremel it off.
 
The brushes need replacing quickly despite appearing meaty, very weak springs it seems.

I do recall many years ago when I had the first Megs model that the brushes needed replacing very quickly. If they came with a spare set It might be worth just popping some fresh ones in, or padding out the old? BOSCH Part No: 1.607.014.145
I might even have some you can have, will update when I venture down to the workshop.
Changing the brushes has saved the day a few times for me on rotary polishers.

Also reading about the variable speed unit as you suggest, seems they were very hit and miss with it not working at all on some lower numbers but then kicked into life on the higher settings.

Good advice from Paulajayne :encouragement:
 
Right, I've bypassed the speed control and it's up and running.
As Matthew mentions earlier it is way too lively for polishing so I'll have to find a way to slow it down to a useable speed.

Electronics people... Is there a single component that I can put in the wiring to slow it down permanently? Or would I be better off getting something like this controller and putting it in a box on the end of the lead? https://www.ebay.co.uk/itm/2000W-SCR-Dimmer-240V-AC-Voltage-Regulator-Heater-1000W-25A-Fan-Speed-Control/292181746872?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649&clk_rvr_id=1455931638404&afsrc=1&rmvSB=true

Out of interest only, what does the speed controller alter? Voltage, current, frequency...?

Oh and thanks for the Bosch part number, I'll get some spares if I can make it useable.
 
I had a similar problem with my Dodo Juice polisher.
I phoned them up and they sent me a new variable speed circuit board, which was easy to fit.
Sorry, just read the last line about no spares available.
 
Thanks Jules, well found, those items would almost certainly do the job if they fitted into the casing. Unfortunately it would cost me £30 to try. I think I'll give my £5 option a try first. If that fails maybe I'll just ebay it for spares and buy myself the ubiquitous Silverline along with a gym course to tone the biceps.
 
Thanks Twisterowner
Googling others' experience with this polisher indicates quite clearly that the makers don't support the machine in any way. The speed unit is a circuit board with semi-potted components on a piece of plastic that fits at two or three points inside the casing. In other words it's definitely not a 'generic' item.
Having said that, I pass D&C several times a week so I will drop in and see if they've any suggestions.
Cheers.
 
Twisterowner said:
Have you tried this firm, which is very near your boatyard?

Damon & Cave Power Tools Ltd
Unit B
Allcotts Yard
Castle Street
Portchester
Fareham
Hampshire
PO16 9PY
tel: 023 92 370 416
http://damoncavepowertools.co.uk/index.html

They have moved back to the old premises, South end of the Fairway. They are only open until lunch time if I have been informed correctly by the lady in the carpet shop in Allcotts.
Click to expand...
 
Alex_Blackwood said:
Twisterowner said:
Have you tried this firm, which is very near your boatyard?

Damon & Cave Power Tools Ltd
Unit B
Allcotts Yard
Castle Street
Portchester
Fareham
Hampshire
PO16 9PY
tel: 023 92 370 416
http://damoncavepowertools.co.uk/index.html

They have moved back to the old premises, South end of the Fairway. They are only open until lunch time if I have been informed correctly by the lady in the carpet shop in Allcotts.
Click to expand...

Thanks for that.
Click to expand...
 
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