Philips oscilloscope

[markm6164]

I don't understand yet how a mains filter works but i'm going to fully research it.

 

[Resqueline]

The Seem filter has only one Y capacitor and a much smaller inductance: 0.1uF X + 4700pF Y + 2 x 4mH. So I find it unsuitable, but it's better than nothing.

The RS filter has no data/values printed on it so I really can't say, but at least it has two Y capacitors like your original. Lacking alternatives I'd go for that one.
It will surely do a good enough job. Given that it has a 1A rating the inductance is likely greater than in the 2.5A Seem filter.

 

[markm6164]

I have searched around and been to farnells this morning with no filters close to mine. The best match i can find is this but will have to see how much shipping to uk will be. Will this filter be ok or can you suggest something better??

http://www.ebay.com/itm/funk-entsto...2x-2500pF-2MOhm-250V-2A-GERMANY-/250915480589

 

[markm6164]

Also can i make a mains filter on a small circuit board or open and repair mine?

 

[Resqueline]

You can use that one too, although the inductance is only 2mH. I'm sure the RS 238-407 filter will do just as well.
You can make your own filter but it involves quite a bit of work to make it (safe).
It's completely impractical to get the epoxy potting out of the existing filter..

 

[markm6164]

I have stripped out the existing filter for educational purposes. The filter layout was something like this.....

 

[markm6164]

Can i ask a really silly question. The main connection on the psu, which way round is live and neutral? Its been a few days and i forgot.

 

[Resqueline]

It doesn't really matter, since the PSU is designed for a "fully floating" mains.
Both phases are "equidistant" from ground, and so there is no designated Neutral or Live.
Here's the mains input section diagram.

 

[markm6164]

Wow how did you get the diagramme so clear? The one i downloaded was blured. Also if i connect the power straight to the psu will my oscilloscope turn on? I have ordered a filter and am waiting for its arrival.

 

[markm6164]

Just answered my own question. I connected mains ac straight to the psu and it works fine. Just need my mains filter now and all will be good again. I have to say a huge thanks to Resqueline. I really appreciate all your help, and i am going to study electronics alot now.

 

[Resqueline]

Yes, it's perfectly safe to connect the mains directly to the power supply. Glad you got it working again.
There are two versions of the diagram on the site I mentioned, one small (blurry) and one large (~250kB). The end of the file name says which is which.
The large one has so high resolution that you'll want at least 2GB RAM in your machine for presenting and processing it with reasonable speed.

 

[markm6164]

Ok well my now mains filter it's all fitted and working fine. I have ordered some new bulbs for the screen back light as they were blown. Next thing I would like to do is get it calibrated. Where can I get it calibrated in the uk or can I do this myself??

 

[Attic]

I have had the same problem with fuse blowing. Found the mains filter faulty. Looking at relpacement from rapidonline.com