EMI Filters & unused plug in cab

[MartyJ]

Hi guys,

My LAH was (AFAIK) a German release.  Whilst still trying to quieten the humming (refer other marathon thread!) I have come down to where the A/C comes into the machine.  There is an EMI filter attached in the silver box which houses the speaker vol.  My questions for the wise ones are:

Can these EMI filters go bad?  Can they be purchased locally and what specs should I get as I think this one is 250v?  Will replacing mine help with the humm that is being amplified through speakers (exists without sound attached)...
Also, from the filter, wires come out and go to this white box / outlet inside the cab.  What is this?  Is this a service plug for the German techs to play their David Hasselhoff music from or does it serve another purpose?  Can this be removed?
Finally, having the volume pot so close to the A/C coming in (only about 1cm or so spacing)?  Could this be causing issues?

[Retropin]

The plug looks like a Shutko (?) plug which is a european plug type - will have straight 240v on it.

Your line filter could go bad - depends on what filter they have installed. They are mainly there to stop emf from washing back down the line.

,,,has got me thinking though with the line noise on your speakers - tried installing dome ferrite rings along the line?
Reduces noise very effectively

[Pinball Fixers]

Hi guys,

My LAH was (AFAIK) a German release.  Whilst still trying to quieten the humming (refer other marathon thread!) I have come down to where the A/C comes into the machine.  There is an EMI filter attached in the silver box which houses the speaker vol.  My questions for the wise ones are:

Can these EMI filters go bad?  Can they be purchased locally and what specs should I get as I think this one is 250v?  Will replacing mine help with the humm that is being amplified through speakers (exists without sound attached)...
Also, from the filter, wires come out and go to this white box / outlet inside the cab.  What is this?  Is this a service plug for the German techs to play their David Hasselhoff music from or does it serve another purpose?  Can this be removed?
Finally, having the volume pot so close to the A/C coming in (only about 1cm or so spacing)?  Could this be causing issues?

Hi Marty,

The EMI filter is there to get rid of any electrical noise on the mains voltage coming in to the machine - ie: Refrigerators, Air Conditioners, Power Tools, etc... on the same power circuit.

This electrical noise can cause the game to do some random things, and even lock up or reset. The EMI filters can go bad, but usually it is after a lightning strike on the mains power, which will take out the Varistor as well (which your machine does not seem to have). Not sure if replacing it will solve the problem, but may be worth a shot.

They are 250V 10A rated. But here are a few different types... Here's one I used recently on a Charlies Angels pinball from Rockby Electronics: http://www.rockby.com.au/searchres.cfm?searchkey=emi+filter&imageField.x=0&imageField.y=0&stock_no=36724, it should be fine for LAH also.

The metal box is earthed, so it should isolate the Volume Pot from any noise. Having said that, the speaker wiring may have voltages induced on them causing some noise heard through the speakers.


The EMI filters can be purchased, but not from Jaycar or Dick Smith... If you are in Melbourne, try Rockby Electronics, RS Components or Radio Parts. In Sydney, try Farnell, WES Components or RS Components... Not sure for the other States, but all of the above will ship interstate.


The white box is a power outlet used for soldering irons or anything else you need to power from mains voltage... you can change this to an Australian outlet if you want to.

[MartyJ]

The plug looks like a Shutko (?) plug which is a european plug type - will have straight 240v on it.

Your line filter could go bad - depends on what filter they have installed. They are mainly there to stop emf from washing back down the line.

,,,has got me thinking though with the line noise on your speakers - tried installing dome ferrite rings along the line?
Reduces noise very effectively

Now I have!

I will definately get some of the ferrite rings tomorrow as they are easily sourced.  I take it they should be installed on the speaker wires out of AMP rather than +5,-12 & +12 input?

Hi guys,

My LAH was (AFAIK) a German release.  Whilst still trying to quieten the humming (refer other marathon thread!) I have come down to where the A/C comes into the machine.  There is an EMI filter attached in the silver box which houses the speaker vol.  My questions for the wise ones are:

Can these EMI filters go bad?  Can they be purchased locally and what specs should I get as I think this one is 250v?  Will replacing mine help with the humm that is being amplified through speakers (exists without sound attached)...
Also, from the filter, wires come out and go to this white box / outlet inside the cab.  What is this?  Is this a service plug for the German techs to play their David Hasselhoff music from or does it serve another purpose?  Can this be removed?
Finally, having the volume pot so close to the A/C coming in (only about 1cm or so spacing)?  Could this be causing issues?

Hi Marty,

The EMI filter is there to get rid of any electrical noise on the mains voltage coming in to the machine - ie: Refrigerators, Air Conditioners, Power Tools, etc... on the same power circuit.

This electrical noise can cause the game to do some random things, and even lock up or reset. The EMI filters can go bad, but usually it is after a lightning strike on the mains power, which will take out the Varistor as well (which your machine does not seem to have). Not sure if replacing it will solve the problem, but may be worth a shot.

They are 250V 10A rated. But here are a few different types... Here's one I used recently on a Charlies Angels pinball from Rockby Electronics: http://www.rockby.com.au/searchres.cfm?searchkey=emi+filter&imageField.x=0&imageField.y=0&stock_no=36724, it should be fine for LAH also.

The metal box is earthed, so it should isolate the Volume Pot from any noise. Having said that, the speaker wiring may have voltages induced on them causing some noise heard through the speakers.


The EMI filters can be purchased, but not from Jaycar or Dick Smith... If you are in Melbourne, try Rockby Electronics, RS Components or Radio Parts. In Sydney, try Farnell, WES Components or RS Components... Not sure for the other States, but all of the above will ship interstate.


The white box is a power outlet used for soldering irons or anything else you need to power from mains voltage... you can change this to an Australian outlet if you want to.

I'm in Melbourne so I will see what I can source tomorrow.  I guess its one of those it either works or it doesn't types of things...

I will remove the white box and extra leads from EMI filter.  Its not needed.

Thanks guys

[MartyJ]

Hi Guys,

Old thread, but similar problem.

The EMI box (silver German one) from my BH is getting a little warm to touch (and made a hiss noise) so I suspect its on the way out.  Is this normal for them to get warm?

For a replacement, any 240 (250v) 10a 50/60 Hz EMI filter is OK?

[Marty Machine]

Sorry, but a big "Ewwwww YUK!" to the designers.....

Move the volume pot way-away form the mains wiring, mount it into a seperate box somewhere else in the cabinet...

Try and pull most of the speaker wires away from the mains wiring loom...
If you leave wires in the same loom (parallel to eachother) you'll get hum probs.

Running the speaker cable perpendicular (90degrees) to the mains wires will attenuate the hum greatly.

I realise most manufacturers were cost-cutting, so there's plenty of short cuts and industry No-No's with their electrical/electronic/pcb designs.

For best practice, you'd want to keep your mains wiring as short and limited as possible in the cabinet, and keep mains on 1 side of the cab, and audio/data wire on the opposite side.
This will greatly reduce interference probs.

MM.

[MartyJ]

That was the old D.E LAH.  Just didn't want to start another thread about a similar topic!

I'm guessing EMI filters shouldn't get warm (not hot)

[Marty Machine]

Filters shouldn't get warm unless it's under-rated.

Some filters are only for light duty 3-5amps, 5-7amps, some are 10-15amps and so on....

It may have been provided (more cost-cutting) on the basis that a standard machine won't draw more current than the capability of the filter, however since adding more lamps or higher current lamps, mods and general current consuming/inefficient 'wear' of certain components, the filter could now be crapping itself.

MM.