[time-nuts] [OT] Re: Solartron 7150plus DMM Failure

Dave Baxter dave at uk-ar.co.uk
Tue Sep 22 08:30:10 UTC 2009


We had a Marconi 6960 power meter power inlet filter do exactly the same
here a few months ago...   As you say, a nasty mess...   Wasn't a
Schaffner filter though...

Just cleanup the mess and replace the filter with a like replacement,
they are all made to a similar specification.   There are some that are
NOT rated for UK/EU power line voltages, however they are rare, but Ex
Military?  Who knows what the original spec was.   Check your power line
voltage too, ours is at 253V most of the time these days.   The kettle
boils quickly!

If you have any concern about the safety of the integrated filtered
inlet, contact Schaffner themselves, they are not difficult to find.
It's unlikely, but there is a remote chance you may get an

Start here...

If you need a replacement, Farnell, CPC, CHS, R&S, etc etc...

Using an external filter, will compromise any emissions filtering, also
any susceptibility issues too, the (however short) pigtail between your
external filter and the meter, will act as an antenna.

As for standing equipment on a "Plastic" sheet to prevent a mess.  Err..
Fire Hazard?

How do I know?...

I work here, it's what we do...


Dave G0WBX.

PS:	63A Three Phase power filters make more of a mess when they "go

PPS:	On the subject of Ex Military...
If anyone in the UK has any X Forces kit of any sort, clothing to
vehicles etc.  If you wish to leave the UK for any reason with it (even
staying within the EU!)  Technically, you now need an export licence.
And it's being enforced by Customs and Excise.

They are even pulling foreign (EU) nationals at the ports, who are
trying to go back home after a recent ex forces gathering in the UK.

> -----Original Message-----
> Message: 1
> Date: Mon, 21 Sep 2009 09:57:51 EDT
> From: GandalfG8 at aol.com
> Subject: [time-nuts] Solartron 7150plus DMM Failure
> To: time-nuts at febo.com, Manual_Exchange at yahoogroups.com,
> 	test-equipment at mailman.qth.net
> Message-ID: <c63.500f1240.37e8e05f at aol.com>
> Content-Type: text/plain; charset="US-ASCII"
> Hi All
> Apologies to any who may receive multiple copies of this but 
> I thought  it worth sending to those lists where I've 
> previously seen mention of this meter.
> I have now had two identical failures of Schaffner filtered 
> mains  sockets on ex-mil 7150plus DMMs, although I'm not 
> suggesting the ex-mil  source is particularly relevant.
> In both cases there has been an internal component failure 
> within the mains  socket that caused it to emit smoke around 
> the edges of the metal filter cover, accompanied by a brown 
> goo and a very unpleasant smell.
> The brown goo is deposited inside the meter in the area of 
> the filter,  and very messy it is too, with a small amount 
> seemingly contained within  the smoke and splattering on 
> adjacent external surfaces.
> In neither case did the meter stop working, or even pause to 
> cough:-), so I'm assuming it's most likely to be the parallel 
> capacitor directly across the  line input that's failed. 
> According to the Schaffner schematic there's no  varistor in 
> there, which might have been a preferred suspect, but there 
> are two  series inductors followed by two more capcitors, one 
> between each power  line and ground.
> After the failure the meter can continue to be used as it 
> stands  but really needs a strip down and good internal clean 
> in the area of the  mains socket, and even then it's still 
> likely to smell unpleasant.
> I don't have time at the moment but will open up the filters  
> eventually and see what might be done to rebuild or just bypass them.
> Just cleaning the filter internally too would probably help  
> reduce the lingering smell.
> As a general precaution I would suggest, at the very least, 
> standing these meters on a sheet of plastic and, if there's 
> anything reasonably close behind  it, wall etc, folding the 
> plastic up behind it too as extra protection.
> The unit that failed here today was sitting on the top shelf 
> of a test bench with its back fairly close to the wall, the 
> wall is looking  better after a good clean but is still not 
> very pretty!
> A longer term fix might be to remove the filter components 
> entirely and use  an external inline filter if required, 
> there isn't much spare room inside the  unit so I don't think 
> an internal stand alone would be an  option.
> regards
> Nigel

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