An update on an earlier post. Partial dismantle completed, and images
here :

http://www.binnsroad.co.uk/misc/powermaster/

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?

Thanks!
--
Graeme

On 03/11/2019 11:46:48, Graeme wrote:

An update on an earlier post.Â* Partial dismantle completed, and images
here :

http://www.binnsroad.co.uk/misc/powermaster/

Plenty of wax, presumably from the capacitor.Â* Question is, can I just
solder in a new one to replace the old, and if so, what?Â* In other
words, is there a modern replacement?

Thanks!

I would recommend a polypropylene axial capacitor, like:
https://uk.rs-online.com/web/p/polyp...itors/1731901/

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.

In message , Fredxx
writes

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
warrant replacement?

--
Graeme

On 03/11/2019 11:46, Graeme wrote:

An update on an earlier post.Â* Partial dismantle completed, and images
here :

http://www.binnsroad.co.uk/misc/powermaster/

Plenty of wax, presumably from the capacitor.Â* Question is, can I just
solder in a new one to replace the old,

yes

and if so, what?

0.1µF 750V

https://www.ebay.co.uk/p/JB-Capacito...tor/1070659712
630V should be enough for any mains application.

In other
words, is there a modern replacement?

Yes.


Thanks!


--
No Apple devices were knowingly used in the preparation of this post.

On 03/11/2019 12:48, Graeme wrote:
Interesting, thanks.Â* 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?


yes

Assuming the cap really is only noise suppression, it may not even
warrant replacement?

I still would.


--
€œIt is hard to imagine a more stupid decision or more dangerous way of
making decisions than by putting those decisions in the hands of people
who pay no price for being wrong.€�

Thomas Sowell

In message , The Natural Philosopher
writes
On 03/11/2019 12:48, Graeme wrote:
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?


yes

Thank you. I wondered afterwards whether noise referred to interference
with TVs and radios, or noise as in voltage stabilisation.

--
Graeme

Graeme wrote:

In message , The Natural Philosopher
writes
On 03/11/2019 12:48, Graeme wrote:
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?


yes

Thank you. I wondered afterwards whether noise referred to interference
with TVs and radios, or noise as in voltage stabilisation.

The former, although not necessarily very effective. If as it appears
this capacitor is across the mains[1] 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.



[1] 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.

--

Roger Hayter

Graeme wrote on 03/11/2019 :
Thank you. I wondered afterwards whether noise referred to interference with
TVs and radios, or noise as in voltage stabilisation.

Noise as in interference to TV and radio, from the train's poor contact
with the track and commutator noise.

In message , Harry Bloomfield
writes
Graeme wrote on 03/11/2019 :
Thank you. I wondered afterwards whether noise referred to
interference with TVs and radios, or noise as in voltage stabilisation.

Noise as in interference to TV and radio, from the train's poor contact
with the track and commutator noise.

Thanks Harry. That was my initial assumption, mainly because many locos
sold in the 50s (think Hornby Dublo) had a wax capacitor across the
centre rail pickup.
--
Graeme

On Sunday, 3 November 2019 11:46:58 UTC, Graeme wrote:
An update on an earlier post. Partial dismantle completed, and images
here :

http://www.binnsroad.co.uk/misc/powermaster/

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?

Thanks!

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.


NT

The Natural Philosopher wrote:

On 03/11/2019 11:46, Graeme wrote:

An update on an earlier post. Partial dismantle completed, and images
here :

http://www.binnsroad.co.uk/misc/powermaster/

Plenty of wax, presumably from the capacitor. Question is, can I just
solder in a new one to replace the old,

yes

and if so, what?

0.1µF 750V

https://www.ebay.co.uk/p/JB-Capacito...Metallized-Pol
yester-Capacitor/1070659712 630V should be enough for any mains
application.

In other
words, is there a modern replacement?

Yes.


Thanks!

Should be enough,[1] yes, but at this point in the cirtuit - mains input
- a capacitor specifically rated as a mains filter capacitor should be
used.

[1] It isn't actually: 230 x 1.05 x 2 x 1.414 = 683V

--

Roger Hayter

On 03/11/2019 11:46, Graeme wrote:

An update on an earlier post.Â* Partial dismantle completed, and images
here :

http://www.binnsroad.co.uk/misc/powermaster/

Plenty of wax, presumably from the capacitor.Â* Question is, can I just
solder in a new one to replace the old, and if so, what?Â* In other
words, is there a modern replacement?

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:

https://www.rapidonline.com/lcr-fe-s...etwork-26-5857



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Roger Hayter wrote:

The Natural Philosopher wrote:

On 03/11/2019 11:46, Graeme wrote:

An update on an earlier post. Partial dismantle completed, and images
here :

http://www.binnsroad.co.uk/misc/powermaster/

Plenty of wax, presumably from the capacitor. Question is, can I just
solder in a new one to replace the old,

yes

and if so, what?

0.1µF 750V

https://www.ebay.co.uk/p/JB-Capacito...Metallized-Pol
yester-Capacitor/1070659712 630V should be enough for any mains
application.

In other
words, is there a modern replacement?

Yes.


Thanks!

Should be enough,[1] yes, but at this point in the cirtuit - mains input
- a capacitor specifically rated as a mains filter capacitor should be
used.

[1] It isn't actually: 230 x 1.05 x 2 x 1.414 = 683V

Sorry! the EU confused me:

230 x 1.1 x 2 x 1.414 = 715V



--

Roger Hayter

On Sun, 3 Nov 2019 20:05:34 +0000, (Roger Hayter)
wrote:

Roger Hayter wrote:

The Natural Philosopher wrote:

On 03/11/2019 11:46, Graeme wrote:

An update on an earlier post. Partial dismantle completed, and images
here :

http://www.binnsroad.co.uk/misc/powermaster/

Plenty of wax, presumably from the capacitor. Question is, can I just
solder in a new one to replace the old,

yes

and if so, what?

0.1µF 750V

https://www.ebay.co.uk/p/JB-Capacito...Metallized-Pol
yester-Capacitor/1070659712 630V should be enough for any mains
application.

In other
words, is there a modern replacement?

Yes.


Thanks!

Should be enough,[1] yes, but at this point in the cirtuit - mains input
- a capacitor specifically rated as a mains filter capacitor should be
used.

[1] It isn't actually: 230 x 1.05 x 2 x 1.414 = 683V

Sorry! the EU confused me:

230 x 1.1 x 2 x 1.414 = 715V

You've just calculated the peak-to-peak voltage of the mains. The old
paper capacitor says 700V DC, but the modern equivalent would be
'X-rated' as someone else has said, and might be marked 250V AC.
--
Dave W

On 03/11/2019 11:46, Graeme wrote:

An update on an earlier post.Â* Partial dismantle completed, and images
here :

http://www.binnsroad.co.uk/misc/powermaster/

Plenty of wax, presumably from the capacitor.Â* Question is, can I just
solder in a new one to replace the old, and if so, what?Â* In other
words, is there a modern replacement?

Thanks!

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.

In message , "dennis@home"
writes
On 03/11/2019 11:46, Graeme wrote:

http://www.binnsroad.co.uk/misc/powermaster/

I can't see a proper earth on that thing.

The earth is soldered directly to the side of the transformer.

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.

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.

--
Graeme

On 04/11/2019 19:10, Graeme wrote:
In message , "dennis@home"
writes
On 03/11/2019 11:46, Graeme wrote:

Â*http://www.binnsroad.co.uk/misc/powermaster/

I can't see a proper earth on that thing.

The earth is soldered directly to the side of the transformer.

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.

Gaugemaster are good, but not enough amps for 0 gauge.Â* Bench power
supplies are great, 0-20v (some 0-30v), up to 5 amps.Â* 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.


the guagemaster do 2.5A

In message , "dennis@home"
writes
On 04/11/2019 19:10, Graeme wrote:
Gaugemaster are good, but not enough amps for 0 gauge.

the guagemaster do 2.5A

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
untoward.

Success! Thank you, all! Two more to investigate, now.
--
Graeme

On 04/11/2019 22:42, Graeme wrote:
In message , "dennis@home"
writes
On 04/11/2019 19:10, Graeme wrote:
Gaugemaster are good, but not enough amps for 0 gauge.

the guagemaster do 2.5A

I'll investigate - thanks.


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.

In message , "dennis@home"
writes

the cased gaugemaster controls are quite expensive.

Far and away the most popular option among users today is a unit made by
Circuit Specialists Europe :

https://www.ebay.co.uk/itm/DC-Bench-...de-Adjustable-
0-30V-0-5A-CSI-3005SM/322572099765?epid=1744012887&hash=item4b1acba0b5:g :
1eAAAOSw3uBZr-J3

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.
--
Graeme

On 05/11/2019 09:03, Graeme wrote:
In message , "dennis@home"
writes

the cased gaugemaster controls are quite expensive.

Far and away the most popular option among users today is a unit made by
Circuit Specialists Europe :

https://www.ebay.co.uk/itm/DC-Bench-...de-Adjustable-
0-30V-0-5A-CSI-3005SM/322572099765?epid=1744012887&hash=item4b1acba0b5:g :
1eAAAOSw3uBZr-J3

The problem with those is they current limit and not trip on a short.
This means there could be enough current flowing to do some damage if
you don't notice and turn it off quick.

On Tue, 5 Nov 2019 09:03:34 +0000, Graeme
wrote:

snip

Many locos, particularly modern production, don't need the power of the
bench units,

When I was designing an Arduino based 'shuttle solution for BIL's OO
layout [1], we found just how different the motors were over the ages
re their power requirements.

Using PWM, if we found a low level setting that might just allow an
older loco to roll along slowly but reliably, the same setting would
have a new loco going along at quite a rate!

So long / short, I think we concluded that rather than going for the
ultimate goal of being able to put any loco on the (automated) track
and expect it to work equally, we would focus on just a few, maybe
even just a railcar or a similar self-contained unit and on an outer
circuit away from all the other / analogue stuff.

Cheers, T i m

[1] The idea was to have a single track run around his layout that
terminated in two sidings at each end. Each 'section' of track (4
sidings and the main run in maybe 3 chunks) to have occupancy sensing
via current and positioning via encoded optical (reflection) sensors.

The idea is that he could have up to 3 locos on the layout at any time
and in any siding on the cct at startup. The controller would test for
occupancy by polling all the sidings and then randomly select one of
the two at the double end and set the points to take it to the empty
siding at the other. The speed on the main run would also be managed
(with inertia) via feedback from the occupancy sensors with the
possibility of a halt / station in the middle somewhere.

We got as far as a short length of test track with a bypass in the
middle and a loco starting at one end, being taken one way round the
bypass on the way up and the other on the way back, accelerating and
decelerating as it did so using the optical sensors near each end (one
to start the train slowing as it approached the end and another to
bring it to a full stop).

We stopped working on it because he moved and he's currently
re-building his layout in the (now well insulated) garage, rather than
loft. ;-)

The idea was to give him something to have running in the background
whilst he's doing other stuff on the main layout and I know you can
buy commercial solutions to do this, part of it was the fun of doing
it oneself. ;-)

I was thinking of getting myself a couple of N gauge railcars and
setting up a similar system up on the walls around a room here.

On 05/11/2019 13:32, T i m wrote:


I was thinking of getting myself a couple of N gauge railcars and
setting up a similar system up on the walls around a room here.


I would use DCC++ and jmri myself.

My occupancy sensors are hall effect latching switches.

The go "on" with a south pole and "off" with a north pole.

Each train has two tiny 3mm dia magnets at each end, N, S ----- S, N

the block stays "on" until the train leaves it when whichever N goes
over the sensor.

On 05/11/2019 13:32, T i m wrote:
Using PWM, if we found a low level setting that might just allow an
older loco to roll along slowly but reliably, the same setting would
have a new loco going along at quite a rate!

I was having trouble like that. Then I got the magnets "recharged"...

Made a heck of a difference. Locos that ran slow and hot then ran cool
and fast.

Andy