Mimic board electrical problem

Shunter46

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3 Apr 2019
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May I please ask for electrical advice ? I have a DC G gauge garden railway I have built during lockdown.
I recently purchased from Brimel Components 4 x MR325 reverse polarity switches with indicator lights green /red to power my LGB turnouts.
I installed the units into my mimic board and they were working perfectly until last week. The problem is that after about 15 minutes use all
the green/ red indicator lights start flashing OFF and ON non stop, this continues until I switch everything off. The mimic board is housed in a fully waterproof control box.I am powering the MR325 switches with a 240v mains adapts that is putting out 1amp. I have been told this is sufficient output to activate the switches and the related track turnouts. I tried a 2amp adaptor but this made things worse.
On closer examination the mains adaptor is getting quite hot.
I than switch it off and when it cools down everything works OK for about 15 mins and then the flashing starts again.
May I please ask your advice ? Is the mains adaptor suitable or do I need to change it
to something else ? I would be very great full for members advice to solve the problem.
Thank you in advance.
 

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
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I assume this is Brimal Components?

These are reversing switches, and apply power constantly, when operated..

Your point motors need a pulse of power only.. Powering then all the time will cause the operating coils to be constantly drawing current. - They will get warm/hot, and you may-well burn them out.
I think your power supply is telling you it is not happy!

As a test (you will not get a mimic display) try running for a while, where you turn the switches OFF after operating the points, and see if this stops the problem occurring.

PhilP
 

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
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Having checked with Brimal...

You require the MR322 for Solenoid point motors..

PhilP.
 

Brixham

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27 Aug 2010
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I too was unfamiliar with these switches, so mr google found them, use mr325 switch.
Anyway, after reading the blurb on the data sheet, they are designed to power track, so are continuous, not points which need a pulse. But Philp beat me to it.

Your point motors are always being powered, so they take power all the time. And your psu starts to struggle after 15 minutes and the thermal cutout is operating.

If you want to keep your toggle switches, then fit every output with a push to make switch.
The leds will still indicate which way the point will throw, but only after pressing the push switch will the point change.
Or, depending on how you have wired your points, fit just one heavy duty push to make on a common wire. But this will energise all the point motors, some points won’t move, others will depending on how many toggle switches you’ve changed since the last big button press.

Malcolm
 

Shunter46

Registered
3 Apr 2019
63
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West Midlands United Kingdom
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I assume this is Brimal Components?

These are reversing switches, and apply power constantly, when operated..

Your point motors need a pulse of power only.. Powering then all the time will cause the operating coils to be constantly drawing current. - They will get warm/hot, and you may-well burn them out.
I think your power supply is telling you it is not happy!

As a test (you will not get a mimic display) try running for a while, where you turn the switches OFF after operating the points, and see if this stops the problem occurring.

PhilP
Thanks Phil
Your advice makes sense. When I used 2 amps it made the problem worse. At the moment it’s raining cats and dogs here in the midlands so when things dry out I will try your suggestion.
Many thanks Don
 

Shunter46

Registered
3 Apr 2019
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West Midlands United Kingdom
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Having checked with Brimal...

You require the MR322 for Solenoid point motors..

PhilP.
Hi Phil
The rain finally stoped and I put all the switches into the centre off position as you suggested things are now cooler but I have lost the lights on the mimic board. So it’s back to the drawing board .
Thanks for the advice.
Don