Electrolux D730 - blown suppressor?

[sharky]

Dear all,

as we know European Eluxes tend to blow their suppressors, and I suppose that this is what has happened with my 1988 D730. Black smoke came out of the back and I turned it off immediately. After further examination and taking the motor apart, it seems as if the suppressor has burned out.

Unfortunately the suppressor is connected to the field coil directly, therefore I don't exactly know what to do now. I can do suppressor removals on UK made Hoovers, but I don't have much experience with Electroluxes. Any suggestions?

regards

 

[madman]

What's the difference? Isn't it as simple as connecting the motor wire to the other lead of the capacitor - the one that goes off to the field coil?

It's a little hard to tell from the pictures, and I'm not familiar with how suppressor capacitors are normally wired, but it looks to me like it is in series with the motor. This is my guess:

LINE -> capacitor -> field -> armature -> field -> NEUTRAL

 

[sharky]

You are right, I suppose. I have to figure a way to connect these in a safe way. Unfortunately the contacts are part of the melted capacitor, therefore I won't be able to reuse them. I could try to crimp the wires together, but they are certainly too short. I'm not a friend of soldering either. Could be worth a try to completely clean the contacts from the capacitor and scratch the rest out.

 

[madman]

Well you only need to keep the one capacitor contact that is attached to the field coil wire. Scrape that capacitor gunk off, leaving only the one contact, put it back where it normally is, and fill the capacitor's hole with silicone. That will keep the remaining contact from moving. Then simply connect the line wire to the remaining capacitor post. No need to cut wires or anything. In fact, it looks like they designed this machine to have the capacitor bypassed whenever it was necessary. Otherwise, they would not have had a blade connector on the capacitor terminal that goes to the field coil. I think the designers intended for you to leave the capacitor in place and just pull the line wire off of the first capacitor connector, and put it on the second.

Also, soldering is very easy. The trick is to get yourself a can of flux and use it. I can't tell you how many professionals I've talked to that dismiss the idea of flux, despite the fact that they use flux-core solder.

 

[repairman]

Curious

Why do British/European vacuums have suppressors in their motors? What do they do?

 

[madman]

I believe they suppress radio interference. Brushed motors do emit a ton of it. I'm pretty sure the European countries had regulations on small appliances that required suppression.

 

[huskyvacs]

MadMan is correct. It might be because of the fact there is a lot of town houses and rowhouses in England and Britain and everyone lived close together. So if someone was vacuuming in one house, it might disrupt the television signal in another person's house, if someone was vacuuming in one room, it might interrupt the radio in another room of the same house, and so on and so forth. Like most electronics they rot as they age and then the suppressor turns into an insulator, traps current and heat, then it explodes.

American (and I also believe Australian) vacuums never had suppressors fitted - so this was something to do solely with UK government.

Obviously with different types of non-analog electronics now and more electrical isolation within appliances, this issue has long since been obsolete and the suppressors are no longer necessary.

In situations where they can not be removed or cut off, I would just put a new capacitor back in there to replace the blown one and call it a job done.

 

[repairman]

Well, in the world of small engines, some spark plugs have an R in the number. (Ex. RJ19LM vs. J19LM) The plug with the R would prevent radio interference if someone was cutting their grass near a TV with the bunny ear antenna.

 

[kb3pxr]

Supressors are needed in Europe for a few reasons.

Suppressors were also important in some European TV systems as they were not as resistant to interference. The UK 405 line, French 819 Line, as well as the 625 line systems used early in Belgium and the SECAM-L system used in France used AM for sound and Positive modulation for video. These were less resistant to interference than the systems that used FM sound and Negative modulation. With positive modulation, interference would cause bright spots in the picture or could even cause the picture to go out of sync. With negative modulation, interference would cause less objectionable dark spots. The suppressor is needed as the motor noise is very wide banded. Australia, did not have this issue as they started TV broadcasting late and used a 625 line positive video modulation system.

Now, Europe has not one, but two AM broadcast bands. They have the medium wave band Americans are familiar with, but they also have a Long Wave band. Long wave is far more prone to interference. In fact, due to this issue, most long wave portables are intentionally configured with poorer quality antennas. The idea is the long wave signal is very strong, but the noise is rather weak. Since motor noise is wide banded, suppressors are needed here too. Australia does not have Long Wave broadcasting, and the noise was tolerable on medium wave.

Historically, Europe also did a lot of broadcasting in the short wave bands. Europe is so close together, there wasn't enough bandwidth in the Long Wave and medium wave broadcast bands to have enough stations. While FM has resolved that, shortwave was used for a long time. Shortwave uses AM for most broadcasting, and signals can be weaker than other bands. Suppression of interference was critical. Again, Australia did not have domestically targeted shortwave broadcasts.

Suppressors do aid in reducing wear on the brushes and the commutator. This is probably not necessary since Australia doesn't use it. Additionally, since the motor runs on somewhere between 220 to 240 volts, you are more prone to generating a lot of RF interference versus the 110 to 127 found in North American vacuums.

 

[huskyvacs]

That is a very detailed answer, thank you. Never knew about the signal modulation (not something there is much public information on).