I have a MRC Twin Power Pack. The overload light has come on and of course none of my buildings lights are working. I am ok on the 12v side and a switches are working. The problem is on the 18v Side. I have given the layout ( 10’ X 16’ ) a visual inspection and do not see any wire problems with the rats nest.
Where do I now start to trouble shoot?
Remove the layout wires from the 18 VAC terminals and see if the short/overload clears. If it clears see if a bulb will light up connected to the 18 volt terminals.
Check your layout wiring for a short.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
At the AC terminals. Disconnect the wires and check the voltage output with a multi meter.
Assuming it’s not the powerpack then you reconnect the wires and follow them to the first available connection point, disconnect that and see if the short goes away. If not, trace back to the powerpack and find the fault. You may as well check for correct voltage at the first disconnect point anyway.
Repeat. Down each branch until you find the short.
Alternatvely, if you’re feeling lucky you could start at any of the points where voltage isn’t getting through and work back to the powerpack in similar fashion. There you’d disconnect each power consumer and label the connection for reconnecting later. The faulty circuit will show up as you make a disconnect and the powerpack returns to normal. You can then troubleshoot just that line and reconnect everything else.
6 of one and half a dozen of the other.
Reliable troubleshooting with no obviously faulty circuit or power consumer is best done from the power input end in my opinion. But either direction will work.
Just resist the temptation to take shortcuts (har, har) because in the long run that just wastes time.
Well snap.
Except you have the expertise whereas I just discovered how to do this by making lots of mistakes first.
If you did something knew wih the 18v side wiring, look there first.
Ok I already checked the voltage. With the short active and the overload light on here were the readings. 12v side read 5.4v 18v Side read 0v. I disconnected the 18 v wire and cleared the short. I then took the measurment. 12v side 12v. 18v Side 18v. so the Power Pack is putting out the right amount.
If I leave the power pack on with the overload on am I taking a chance of hurting the elec system as I am lookung for the short or should I shut it off each time I move (Big Pain )?
Yes! With the 12 volt side dropping to 5.4 volts the short is putting a heavy load on the power supply.
As the problem is on the 18 volt side I would use a couple of automotive bulbs in series (1157 or equivalent) in series with the load, the 1157 bulbs are 14 volt so a single bulb won’t last very long at 18 volts.
The bulbs will glow at about half brightness indicating a short in your wiring. When you disconnect the wire with the short the bulbs will dim or not light up at all.
You didn’t say how many circuits on the 18 volt terminals or what kind of lighting you are using.
EDIT:
It would help diagnose your problem to include more details, type and quantity of lighting, the model of your MRC power pack.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
I will give you more info on Sat as I am going out of town. There are about 10 buildings. All bulbs are incandescent. I am running Prodogy and the AC power pack has no reset button. Power pack is original abount 12 years old. The layout is a 10 x 16 ft and the control panel is 4 ’ in from one end. The problem is in both directions from the power pack.
I’m also running Prodigy but my power supply only has one 15 volt DC output. I also have incandescent bulbs for lighting.
Our layouts are close to the same size, mine is 10’ x 14’. I have a total of 16 structures, all incandescent bulbs. I use 12 volt 2, 3 and 4mm bulbs operating at 8½ volts for 1950s realism. About 250 total bulbs drawing about 6 amps from a 12 volt 30 amp switching power supply, I use DC to DC buck converters to supply regulated 8½ volts to my bulbs.
Each structure is on its own homerun circuit to my control panel. Randy got me hooked on Arduinos and I have 8 structures operating off Arduino Random Lighting Controllers. Each controller has 20 outputs, they drive 160 bulbs.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
Hello All,
Thank you for letting us know your timeline on responses and that you are not “ghosting” us.
A few questions to consider and reply to:
The “load” (Amperage) of the lights should be determined to understand if you are overloading the capabilities of the 18-volt circuit.
Most electrical devices will list on their specifications not only the voltage but also the amperage.
OK, I’ll try to explain this in the simplest terms possible (Others with practical electrical knowledge feel free to chime in).
If this is too pedantic please excuse me.
With electricity, there are three parameters: Voltage (V), Amperage (A), and Hertz (Hz).
Unless you are dealing with European electrical equipment Herts is not a factor. North American power runs at 60 cycles per second or 60Hz.
Most North American electrical grids are based on 110 to 120 Volts. Again, not a problem unless you are dealing with European components.
Amperage is determined by the “load” or electrical “force” necessary to push the electrons to power a given load. Also known as “draw”.
When the breaker in your home “Trips” or faults, it’s the Amperage that is causing that to happen- -not the Voltage or Hertz.
For example: If you put three components that “draw” 5 Amps each your “load” is 3 x 5 Amps = 15 Amps.
If the circuit breaker is rated for 15 Amps you have reached it’s “limit” or potential.
When you add a fourth component rated at 2 Amps you have exceeded the Amperage of the breaker and it will trip or “fault”.
The more often the breaker trips it physically takes a toll on the electric
There’s a list of available MRC power packs here:
https://www.modelrectifier.com/Articles.asp?ID=253
The only one I see listed as a “twin” has a rating of 14.5 VA. VA is comparable to watts as it is a combination of, volts and amps. It is called Twinpower 202.
Knowing the exact model will help.
14.5 VA at 16 volts is only .90625 amps. That’s total output so whatever is being siphoned off to run the Prodigy is sucking current from the AC lighting side, too.
Good Luck, Ed
[If not , can I disconnect the red wire going to the 18v side and connect it to a 12v dc Reg? If the lights come on it would indicate the breaker is not up to par.]
Move both wires, I doubt if there is a common ground between the 18 volt and 12 volt terminals.
[If this helps. There are only about 25 incandeant bulbs attached to the 18v side. I now light with 12vdc reg or arduino]
Explain how you have your lighting hooked up. Is it working on 12 volts but not the 18 volt side?
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
There is a common ground on the power pack. Wires go from pack to Terminal strips and then individual buildings. I do not remember why but the common ground wires go to a Bridge rec first.
The 12v side is controling switches and all is working.
The 18 volt or Accessory output is normally AC, that would explain the bridge rectifier.
I still don’t understand how you have your lighting hooked up, you mentioned Arduino and they are a 5 volt processor. They have an internal 12 volt to 5 volt regulator at very low current.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
Forget Arduino. Those are some special lighting curcuits and have nothing to do with the other buildingds
Have you tried swapping the wires to the 12 volt side?
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
Aging is not for wimps.
The Tech 780 is a twin throttle powerpack also.
There can’t be a common ground for the AC accessory side and the nominal 12v DC side.
There seems to be some confusion. I stated above. The power pack Model is AH800. It show 12vAC 18vAC and 65VA and has a common ground. I do not know how to convert 65VA into amp output.
My question still is the same. Can I attach the red 18v connection to the 12v side without damaging anything? Is there a seperate breaker for each side?