An update on an earlier post. Partial dismantle completed, and images
Plenty of wax, presumably from the capacitor. Question is, can I just
solder in a new one to replace the old, and if so, what? In other
words, is there a modern replacement?
I would recommend a polypropylene axial capacitor, like:
You may get cheaper, perhaps look on eBay.
Polypropylene caps are rugged and self-healing. The only issue is their
max temp of 105C which I hope isn't going to be an issue.
Having a rethink, without knowing more about the device I'm not certain
this cap does any more than noise suppression and it's failure may be a
red herring. Best check the transformer first or the fuse if there is one.
Interesting, thanks. Yes, the fuse in the plug blew, so it would be OK
to remove the blown capacitor then reassemble, fit a new fuse in the
plug and test the output with my trusty analogue multi meter?
Assuming the cap really is only noise suppression, it may not even
The former, although not necessarily very effective. If as it appears
this capacitor is across the mains then you should get one
specifically rated for this service and preferably the same value (0.1
microfarad). This is generally called an X rated capacitor, suitable
for mains filters at 240v, in the description But they are fairly cheap
and reliable if from a reliable supplier.
Fortunately I think it is fairly likely that failure of this capacitor
caused the original fault.
 In the unlikely event that the capacitor goes from one side of the
mains to earth then you probably don't want to replace it, for reasons
that could be discussed if this applies.
Should be enough, yes, but at this point in the cirtuit - mains input
- a capacitor specifically rated as a mains filter capacitor should be
 It isn't actually: 230 x 1.05 x 2 x 1.414 = 683V
On Sunday, 3 November 2019 11:46:58 UTC, Graeme wrote:
It's a paper 0.1uF 750v. The high v rating suggests it's across the mains, in which case replace it with a 0.1uF X2 type cap, they're generally rated to 275v ac. It ought to work ok without the cap.
The unit also has a metal rectifier by the look of it. I hope it's not selenium... :) Best power it up outdoors.
It looks like that was just a mains filter cap. If it was across the
mains (as its working voltage would suggest) then it may have failed
short and taken out the plug fuse when it failed. If you chop it out,
replace the fuse and re-test then chances are all will be well.
You can then replace it with a modern mains input suppressor - these
normally have a 0.1uF cap in series with a 100R resistor, like:
I can't see a proper earth on that thing.
Gaugemaster do nice new ones with a lifetime warranty.
I bought a s/h four channel one with one faulty channel and sent it back
and they repaired it without question.
The earth is soldered directly to the side of the transformer.
Gaugemaster are good, but not enough amps for 0 gauge. Bench power
supplies are great, 0-20v (some 0-30v), up to 5 amps. The Powermaster
supplies 0-12v up to 2.5 amps, which is plenty for most locos, and far
more than a Duette or other, similar, later models.
I'll investigate - thanks.
Got the Powermaster reassembled today, after unsoldering and removing
the blown capacitor. Good job I took plenty of pictures!
New 3A fuse and yes, it powers up. Checked output with multi meter and
all as expected. Left sitting on but with no load for 3/4 of an hour,
then used for 5 minutes, drawing about 8v, 0.6 amps. Case slightly
warm, as usual, and the usual mild electrical smell, but nothing
Success! Thank you, all! Two more to investigate, now.
the cheapest option is the panel mounting controllers and a toriodal
transformer from somewhere like cpc.
the cased gaugemaster controls are quite expensive.
IIRC an O gauge panel is about £60 and the same thing in a case with
transformer about 200.You could buy a 20A 12V PSU of ebay and a 10A buck
converter to modify modify (replace the 10 turn pot with a normal one)
for about £20 the pair.
Far and away the most popular option among users today is a unit made by
Circuit Specialists Europe :
I have one, and a similar unit from Maplin, and both work extremely
well, but are similar in price to Gaugemaster and others, which is why I
am trying to use old Powermasters, often available for a fiver.
Many locos, particularly modern production, don't need the power of the
bench units, so, with a patch panel and 4mm banana plugs, matching
controller to loco is straightforward. The built in volt and amp meters
in the bench units are useful, as some locos date back to accumulator
days, requiring only 4 or 6v, but a lot of amps.
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