Hoover suppressor

[Madrat66]

Hi everyone,

I need to change the suppressor on a 40 year old hoover porta power. I know you can just remove them but I don't like the idea of it, they are there to stop interference and minimise sparks on the brushes, however I have no idea what to look for in a replacement. Can anyone please help.

[evingar]

If worst comes to worse, you could make one up with separate caps -

X2 0.0047uF "Y" type to ground
X1 0.1uF "X" type across the supply

As per the diagram on the suppressor.

You might even be able to fit them in the original can.

[Madrat66]

Possibly a bit beyond me, a direct replacement would be better but what to go for

[Diabolical Artificer]

https://www.hooverspares.co.uk/capac...pl?pid=1142376 ?

[Madrat66]

That's a bit steep price wise. 😳

[Refugee]

I know a place where you can get a real human on the phone.
It is my go to place for appliance spares.
https://www.google.com/maps/place/Ba...6!4d-1.4275855

[Madrat66]

😃 thanks 👍

[Madrat66]

What are your thoughts on this?

[evingar]

Well it's better than nothing, but it won't have the same characteristics as the original as that also has two 0.005 uF caps to ground.

[Madrat66]

This is what's confusing me, there is no ground on the machine or dose that just mean the motor casting?

[Madrat66]

Found this one. Just a thought the dyson motors have a yellow 2 pin suppressor fitted could I use something like that ? As long as it doesn't interfere with FM or anything else or burn the brushes I will be happy.

[Herald1360]

RS do a suitable value three legged RIFA "smoke bomb" (probably OK for ~10+ years)

https://uk.rs-online.com/web/p/film-capacitors/0239668

[Madrat66]

Brilliant thanks 😊

[6SN7WGTB]

Does this sort of capacitor actually suppress sparks on an AC motor?

Wouldn't you need a CR series combination?

On interference, although I am a bit of a bandit for chasing down RFI ruining my MW/LW/SW/VHF, I'm not sure even I'd bother with interference suppression on an intermittently used device.

[Madrat66]

Well they were fitted for a reason, so I would rather replace.

[Refugee]

They reduce sparking of the brushes increasing their life.

[6SN7WGTB]

Originally Posted by Madrat66

Well they were fitted for a reason, so I would rather replace.

Understand entirely.

Aside potential reduction in sparking at the commutator, I do recall they were fitted for Radio and TV Interference suppression, and in fact to comply with legislation for which there were BS guidance booklets:

BS 613: 1955 "Specification for the Components and Filter Units for Radio Interference Suppression"

BS 2135: 1966 "Specification for Capacitors for Radio Interference Suppression"

However I do note that"the move away from the VHF band for television transmission in the UK has lessened the likelihood of interference by any but the most severe equipment problems".

[6SN7WGTB]

Originally Posted by Refugee

They reduce sparking of the brushes increasing there life.

I'm sure there may be a benefit as any ionisation on a carbon surface must result in some combustion, amd providing something to suppress the magnitude should help.

I actually did some research on this for small DC motors for model railways - where the same two arguments apply about RFI (principally) and brush life (secondarily).

In that particular instance I was able to prove that RFI was significantly suppressed in magnitude by an appropriate value of across-motor capacitor. Further reductions relied on slightly more complicated LC networks, and/or more components applied to track connections and so on.

At a fairly subjective level, sparking at the brushes was not visibly changed, but the RF output was objectively lower. Didn't run a long enough test to comment on brush life.