Thread: Suppression Capacitor on Power Tool.... Please HELP !!!

Originally Posted by MikeThePom

HCIM et Al.
Last year I was in a similar position with a bosch electric hammer power drill, it too had been unused for a period of about 18 months and the first time i used it it went bang. The suppressor cap blew up. I contacted Bosch, just around the corner in Clayton and the tech said that it could be ordered in from Germany at about the same price as you were quoted. However, a power drill repair technician said that for many drills he had simply left them off without any undue problems. i took his advice and haven't had any problems with interference when in use. BUT I am not recommending that you do the same.

Regards

Mike

dakotax3 wrote:
Yes, I did wonder about that myself. A lot.

Me too !!
It sounds like the simplest solution, at first instance. I've been recommended to do this "short-cut" too by several repair technician that I consult with. Then I remember that they have a common middle name. 'Danger' is their middle name...!!!



@ Gerhard:
I just want to PM you regarding this problem..., but I just PM on another issue, so don't wanna bother you too much. Seeing your post here is like a dream come true !

Thank you very2 much for the comprehensive explanation and detail regarding the Suppression capacitor in power tools.
You've answered most questions that's been spinning in my head regarding this Capacitor issue.

I'll take your advice to look for an MKT type with specific cap value and a high enough voltage rating.

Once again, thank you very much for help.

Regards,
Mich

Hi all,

just now i came across a pic i made from a 2000 Watts Fein MSf679c angle grinder, which i bought second hand through Ebay Germany in 2008. The seller claimed that it worked fine, which i find hard to believe after having discovered all this tinsel inside the machine.

Once again i was glad to have stuck to my trusted routine to never plug in and try an unknown used machine before having checked inside that it's okay to switch it on. This routine has saved me several sh*tless scares, blown fuses and probably some real hazards or injuries as well.

This pic is a good illustration of the mess that an exploded suppression capacitor can make. This XY-cap had a value of 0.3 uF + 2x 4700pF and it was an aluminium foil type with waxpaper insulation layers rolled in between. These types are especially known to pop their contents with force, since the wax vaporises and expands much more intensely and quickly than any plastic foil material will. It is clearly visible that the amazing amount of thin aluminium foil has spread inside the machine like wallpaper or is torn away as loose chunks. The remains of the capacitor are highly likely to cause a short-circuit and if they won't, there is also a high chance that the splattered chunk or tinsel will do so.

There are several reasons for such caps to blow. Often it's overvoltage, but old age (deterioration of the insulation), dampness (entering inside and oxidising the foil, expanding, tightening, cracking or deforming the cap's shape) or heat can also play a role. In this case it was a suddden seizing, stalling or binding of the disc, because i also found traces of very sudden harsh forces on the gears and bearings. During the resulting high Amp intake of the motor, the machine has probably been switched off when at the same moment, purely by coincidence, there was switch contact arcing or maximum mains voltage peak, causing a one or more very high reverse voltage spikes. This will have damaged the cap, resulting in a bigger shorting and this spectacular blowup the next time the machine was switched on.

Also visible is the nice state that the machine is still in; it was built in the latter 80's and has obviously not seen much use after that. The user may have been scared off to such an extent that he may never have dared using this machine again. When this has happened not too long after the machine was puchased new, you may be in for a bargain as long as the motor is not damaged. An inspection of the collector strips will soon tell you if that is the case; when there are no burnt edges and uneven blackened spots the motor is very likely to be unharmed.

I changed the bearings and the cap (three parallel 0.1 uF MKT types to make the X-component and two 4700 pF MKT types for the Y-caps) and the machine now looks and behaves like new.

greetings

gerhard

(good luck in Queensland after this huge hurricane!)

Than you Gerhard, for the best discussion of suppression caps I have ever seen on the web!

A lot of these issues are caused by Australian voltage and the fact a lot of stuff is designed with 220V in mind with the excess is covered by tolerance. If you build the thing you will find parts easilly but the nomenclature may differ. IE the 2,200pF may be 2.2 Nano F or 2N2. 250V AC is a bit sus, I would prefer far higher, IE 400V AC or 6KVDC (preferred values are 1KV 2KV and 6KV.
Pricing the parts I found cost without the packaging needed to house it was about $4 using 275V AC and 6KV DC caps. Again some skill is needed in assemly etc so it may not be worth mucking around unless you have no option.

to hcim
last week i get a sander metabo sr220 (old machine) to fix it, and i have same problem with you to get that spare-part,
and i have solution for it,
1. you can use Alternative exp : 0,2uf + 2x2200pf 250v
you can use 3 Capacitor by combination it parallel and series it
this how to make it. a. 2x2200pf you make a series 2 capacitor 2200pf --H--x--H-- (--H-- is a capacitor) and (x is solder and Connected cabel to body machine)
b. make parallel capacitor 0,2ff 250v and the 2x2200pf (a point)

2. you can (not use) it part, you machine will fine not need it,
or just use 0,2uf 250v capacitors no need 2x2200pf.
that it all for me... if u have other question u can email me...

from indonesia.

Originally Posted by jakasrinaga

to hcim
last week i get a sander metabo sr220 (old machine) to fix it, and i have same problem with you to get that spare-part,
and i have solution for it,
1. you can use Alternative exp : 0,2uf + 2x2200pf 250v
you can use 3 Capacitor by combination it parallel and series it
this how to make it. a. 2x2200pf you make a series 2 capacitor 2200pf --H--x--H-- (--H-- is a capacitor) and (x is solder and Connected cabel to body machine)
b. make parallel capacitor 0,2ff 250v and the 2x2200pf (a point)

2. you can (not use) it part, you machine will fine not need it,
or just use 0,2uf 250v capacitors no need 2x2200pf.
that it all for me... if u have other question u can email me...

from indonesia.

Salam Kenal !!

Wow..., nice to see another woodworker from Indonesia here.
Many thanks for your kind suggestion and solutions.
IN FACT, I've done the what was suggested by Gerhard in previous page (which is very similar with yours). I just put one X2 Caps 0.22uF 250V .... and .... It works fine!
Sorry for this late update.

FYI, finding this kind of Caps , even just a single 0.22uF is NOT easy here.

Regards,
Mich

Originally Posted by hcim

Salam Kenal !!

Wow..., nice to see another woodworker from Indonesia here.
Many thanks for your kind suggestion and solutions.
IN FACT, I've done the what was suggested by Gerhard in previous page (which is very similar with yours). I just put one X2 Caps 0.22uF 250V .... and .... It works fine!
Sorry for this late update.

FYI, finding this kind of Caps , even just a single 0.22uF is NOT easy here.

Regards,
Mich

salam kenal juga

to find those cap is very2 easy.. in glodok (jakarta) or cikapundung (bandung)
if u want find the original cap it very2 hard to find in indonesia but u can by from aus (australia) but very expansive

u can use milar, cramik ,mkn...ect. who can use in ac power supply just find rage up from 250V to 400V for exp i use milar cap and cramic cap 360v.
if u use 250v cap is very good for u machine but it easy blow up / broke down if voltage more then 250V and if u not use it for long time it will blow up. like my old vacum cleaner hehehehe...

Thank you to this great forum and post here ! I just googling it and found your very bright idea, so I can 'save' and use my 1980 BOSCH (still Germany !) drill.

Yes, finally after give fully 31years of service, suddenly a PLOP sound heard inside the handle and my fuse's StepDown Stavolt is down ( I use StepDown Stavolt because drill is stil 110V and AC line is 220V). At first think the motor is burned but nothing smell burn. And beside logically the fuse is down something to do with short circuit.

For the 1st time the drill is opened,motors looks still good and saw bulge X2Y capacitor (150nf + 2x2500pf 250V) with top of it leak. (150nf=0.15mjufarad) Also a white residue form on the case, seem it's already leak for a long time but just when I use it for long time then finally it give up. 'First aid' to do after reading this forum is to dismantle the capacitor from main switch and viola the drill work again. So confirm you can use the tool it without capacitor, but QUESTION how realible without it.... ?

Contacting BOSCH service center here they dont have any replacement cap. Even I asked the equvalent from new model, they said that mostly new product dont equip with this part again. With reason, radio noise problem is not too much happen in this modern day,as modern gadget already have their own fillter. WOW..surprised me, by reading this forum we can know the hardware may wear out more rapidly... Maybe it's marketing strategic or a reason such 'new tools' don't last enough comparing to old tolls nowadays ?

Looking for X2Y capacitor is quite hard here, so I ready to change only X2 caps. Even many store here didn't know much about this XY condensator (with 3 output) they just new normal caps. But lucky me, small store with an old aging owner know what I am looking for. He can only provide X12Y 68nf+2700pf (250V) from his stock.... You see 68nf is not close enough to cover 150nf. While Y part is more/equivalent to original. But smartly he give me 150nf X2 MKT (275V) capacitor and suggest me to parallel with 68nf, so combine it almost 220nf.... Great idea... He suggest to keep use Y part as long I can get it. To use only X2 cap is for last option only if can not find adequate XY caps.

The problem is only for small room left on the handle to put/combine the part. I was desperate to put only X2 MKT Cap, but a little effort squeeze and arrange the cable, it can be fitted. Also, I am hate to do solderimg Don't forget while you open the tool to check other part, like clean & lubricate/grease the bearing.

Then cross the finger, connect back to 110V stavolt, YES IT WORKS So seem this drill will give more lengthy service

Thanks to forum comment, esp gerhard,hcim, Pak Srinaga which kind email and send pic to me !

regards,

Originally Posted by jakasrinaga

salam kenal juga

to find those cap is very2 easy.. in glodok (jakarta) or cikapundung (bandung)
if u want find the original cap it very2 hard to find in indonesia but u can by from aus (australia) but very expansive

u can use milar, cramik ,mkn...ect. who can use in ac power supply just find rage up from 250V to 400V for exp i use milar cap and cramic cap 360v.
if u use 250v cap is very good for u machine but it easy blow up / broke down if voltage more then 250V and if u not use it for long time it will blow up. like my old vacum cleaner hehehehe...

OK Pak Thanks for your PM, seem my tools is cover enough with 250V (since its operated only 110 VAC).... Yes, many new vaccum cleaner is not good as old one, just like cheap small vaccum they sell in HARDWARE store... We must admit old tools sometime with proper care can overlast new one... But indeed new one have more advantage like variable speed, L/R rotation change/dual rotation and IMPACT function

Hi Wap,

great to hear that you were successfull in repairing your Bosch drill ! As for the original capacitors, these mostly used wax impregnated paper as insulation layers between the two metal foil layers. The white stuff you encountered was partly evaporated wax and partly residue from the shorted foil and heated sealant that keeps the cap shape and its wires in place. A shorted capacitor usually blows a fuse but leaves the motor unharmed, provided the motor was not faulty itself and was the cause of the capacitor being damaged.

XY-caps (including the two small Y-connected filter caps) are nowadays indeed rare and expensive items. The need for thorough high frequency filtering in no longer there, since modern receivers are of far better quality than some decades ago, so most household appliance and tool motors are at present fitted with X-caps only. So it is no problem whatsoever to refit a tool with an X-value capacitor only when its original XY-type is blown up. In that case go for the first and largest value, which is the X-value. Eg., if the old cap reads 0.2 uF + 2x 2500 pF, replace the cap with a single 0.2 uF cap or solder two 0.1 uF in parallel when 0.2 is not available. The modern X-caps have plastic insulation foils of high quality, far superior to the old wax paper types. The MKT-versions even have limited "self-healing" properties (if a slight flashover through the plastic foil occurs, the plastic is designed to melt and seal the pinpoint hole shut again, to prevent a larger flashover).

Old vacuum cleaners (often with motors up to 500 atts and 0.1 to 0.15 uF caps) will also work fine X-only caps. Modern vacuum cleaner motors are fitted with X-caps as standard, so there you go.

The use of a capacitor in a tool or brush motor appliance is always recommended, since it reduces brush and commutator wear and dampens voltage spikes "polluting" the mains power sine wave. A brush motor will work fine without a cap, but it will show more brush sparks and will wear quicker. Motors subjected to very heavy use or overload will experience a lot of coil wire temperature changes between normal surrounding air temp and extreme heat.
A lot of such changes makes the wire insulation lacquer go brittle over the years or may crack or deform the layer, inviting quicker short circuiting between adjacent winding loops within the tightly wound and packed coils. So by dampening voltage spikes, the capacitor even contributes as a flashover countermeasure for the motor coils. Therefore i do recommend replacing the cap when the original one is broken or missing..

As for Bosch: this brand was always particularly keen on doing it right. On top of using XY-caps, the Leinfelden factory and its partner Scintilla even used small choke coils in the leads towards the motor brushes. This was an extra measure to further dampen spark generated radio noise by some additional deciBels. The finnicky apporach by Bosch can be explained by the brand also being active in the radio transmitting system market. Bosch in Europe is also known as a reputable name in radio controlled devices, emergancy sercive radio equipment and telephony solutions. As such the brand has a reputable name in the world of firefighting and ambulance staff. The high frequency knowledge of the firm was clearly put to good use inside Bosch and Scintilla power tools.

greetings

gerhard

A nice further additional brilliant explanation from the master. For other who may not so lucky (or hard) to find XY just use X type (X1 or X2) caps sufficient enough to protect the tool
It's fit describing by BOSCH technician here just in modern day their equpment may simplify the noise/storing part in their power tools

Thanks Mr. gerhard... !! I am happy to read your confirmation

Greeting
Surabaya-EastJava Indonesia

Thanks Gerhard for clarifying the XY capacitor.

Looking for a replacement for a vacuum cleaner that had a cap blew up.

MKT type not available in the right size (0.15uF). Found MKP type which is polypropylene film and designed for pulsed AC, high quality +/-5% and for high current but not specified. Found it via RS - see my example capacitor Buy Plastic Film Capacitor,AC and Puse,MKP 1839HQ,Polypropylene,31.5x10mm,Axial,0.8mm Lead,850Vdc,5%,150nF Vishay MKP1839415084HQ online from RS for next day delivery..

Vishay product info http://www.vishay.com/docs/28162/mkp1839h.pdf

I find RS pretty good since they have a huge range of product and deliver for *free* even uneconomical quantities.

Hi BLouis!

best wishes for 2012!

Thanks for the compliment, glad to have helped you. Yes, the Vishay product line offers good solutions, with plenty of choice. Great to hear that you saved yet another appliance, increasing its lifespan and saving raw materials.

greetings!

gerhard

Originally Posted by blouis79

I find RS pretty good since they have a huge range of product and deliver for *free* even uneconomical quantities.

I'm not a huge fan of them or Farnell.

Complete ripoff, prices are 2x the US if not more. Plus they don't pick small quantities of most parts. Minimum quantities can easily blow out your costs. Was looking at adding a few shift registers in with an order and they only offered the whole tube of 100.

Digikey or Mouser in the US will pick 1 single resistor for you if that's what you want.

The $30 shipping fee is easily covered by getting some other stuff to fill out the order, especially good quality electrolytic capacitors and obscure ICs.

Plus their customer service is fantastic, digikey picked $35 of the wrong parts. I told them so on their 24 hour online chat service, they let me keep them and sent the right ones by overnight international courier. The right ones were only worth a few dollars too.