Transformer Woes

[RobertInOntario]

When I got back into model railroading around 2005, I bought two new DC transformers. Both were by Railpower, one was a Railpower 1370 and the other one was slightly weaker. Well, the weaker one died about 2-3 years ago and I replaced it with an Athearn transformer. (The Railpower 1370 is still going strong.)

This Athearn one has worked well -- wide range of control, especially at slow speeds, etc. -- until just recently. Tonight, it stopped working for a bit then started working again, although it seems now I have to turn in up higher to get the trains to run at their usual speeds. I've also just started to use this transformer to power a switch on a turnout, so I'm not sure if I'm putting too much extra strain on this transformer by using it to power this turnout switch as well as to run the trains.

The throttle / handle of the Athearn transformer also feels a little loose, like something inside it needs tightening.

So, am I somehow extra-hard on transformers or do they only last for 2-3 years before they burn out? (In terms of use, I usually operate my layout(s) several times a month, ranging from 1/2 hour to 2 hours.)

Thanks,
Rob

[Green_Elite_Cab]

I have several ancient controllers, and more recent ones by model power and Bachmann Spectrum( from 2003). they have not yet ever crapped out on me.

I can't see powering a switch with the controller being an issue, since it should only be drawing power when you use it.

My only concern is if the switch may be drawing power unintentionally. I had some Atlas Remote Turnouts, where you slide the control switch and press it down momentarily. Several times I've thought that the motor was switched and that no more power was flowing to the switch, only to find that the solenoid had quite literally burned its way out of the plastic switch machine. Needless to say, i no longer use remote turnouts of that type.

Perhaps your switch machine is drawing power through a short of a defective/unreliable piece of hardware. I would disconnect the switch if you haven't already then see what happens.

As for the controller being loose, it might not hurt to open it up carefully, noting the location of all components and then manually tightening up whatever screw holds the controller dial/lever in. I'd probably take that opportunity to search for visible signs of damage, such as burnt components.

If you see damage you're not sure you can fix, it may be time to retire the controller or use it for less strenuous purposes.

[RobertInOntario]

I have several ancient controllers, and more recent ones by model power and Bachmann Spectrum( from 2003). they have not yet ever crapped out on me.
I can't see powering a switch with the controller being an issue, since it should only be drawing power when you use it.
My only concern is if the switch may be drawing power unintentionally. I had some Atlas Remote Turnouts, where you slide the control switch and press it down momentarily. Several times I've thought that the motor was switched and that no more power was flowing to the switch, only to find that the solenoid had quite literally burned its way out of the plastic switch machine. Needless to say, i no longer use remote turnouts of that type.
Perhaps your switch machine is drawing power through a short of a defective/unreliable piece of hardware. I would disconnect the switch if you haven't already then see what happens.
As for the controller being loose, it might not hurt to open it up carefully, noting the location of all components and then manually tightening up whatever screw holds the controller dial/lever in. I'd probably take that opportunity to search for visible signs of damage, such as burnt components.
If you see damage you're not sure you can fix, it may be time to retire the controller or use it for less strenuous purposes.

Thanks. First, I think I'm going to re-attached my wires to the controller more carefully and neatly as I think that could improve things. Also, I'll do as you suggest and try using the transformer when the switch wires are not connected to it. I'm not too keen on taking it apart myself but a guy at my LHS might be able to.

Thanks again,
Rob

[BR60103]

Rob:
It may be worth putting n ammeter into the circuit to see what the curent draw is and compare it to the rating of the power pack. Some of those old locos draw quite a bit of current and may be overloading the circuit breaker. Another device to put in is a car tail/brake lamp bulb; this will light up for a heavy draw (show glow faintly for two Dublos double-headed).

[RobertInOntario]

Rob:
It may be worth putting n ammeter into the circuit to see what the curent draw is and compare it to the rating of the power pack. Some of those old locos draw quite a bit of current and may be overloading the circuit breaker. Another device to put in is a car tail/brake lamp bulb; this will light up for a heavy draw (show glow faintly for two Dublos double-headed).

Thanks, David. I took the transformer to an LHS today and they checked it out (as you describe) and it seems fine. However, it still seems like I have to crank it up more now, especially compared to my other transformer. Maybe the older Triang & Dublo locos are taking a toll on it.

I've also found out that I have some track-related problems. Some connections between my track have poor connections, yet soldering doesn't seem to be helping a lot. I did some trouble-shooting tonight & found this out -- I've either got to improve my soldering ability OR find out exactly where to solder (or maybe both!).

Cheers, Rob

[nachoman]

Can you post the model number of the Athearn power pack you are using (or at least the amperage rating) and the type of turnout control? Power packs, or transformers, should not burn out that easily. Almost all have some kind of overload protection for safety. On a simple transistorized pack, the inside electronics should not be so sensitive that they can't take a little abuse. Of course, if you shorted it out or overloaded it on a regular basis, or your home experiences frequent voltage spikes - the electronics are more likely to fail.

I'd check a few things before buying a new power pack:

1) It could be your layout wiring, or the wire connections to the pack. Make sure there isn't the tiniest strand of wire that has come loose and is bridging the terminals.
2) As previously mentioned, it could be that your pack is not rated high enough for the locos you are using. Older locos can draw as much as 3/4 of an amp. Newer locos may only draw 0.1-0.25 amps.
3) while you are experiencing problems, tap or flip the on/off, direction, or any other control switches. From my experience, an intermittent power pack is likely to be caused by a switch that is wearing out.

[RobertInOntario]

Can you post the model number of the Athearn power pack you are using (or at least the amperage rating) and the type of turnout control? Power packs, or transformers, should not burn out that easily. Almost all have some kind of overload protection for safety. On a simple transistorized pack, the inside electronics should not be so sensitive that they can't take a little abuse. Of course, if you shorted it out or overloaded it on a regular basis, or your home experiences frequent voltage spikes - the electronics are more likely to fail.

I'd check a few things before buying a new power pack:
1) It could be your layout wiring, or the wire connections to the pack. Make sure there isn't the tiniest strand of wire that has come loose and is bridging the terminals.
2) As previously mentioned, it could be that your pack is not rated high enough for the locos you are using. Older locos can draw as much as 3/4 of an amp. Newer locos may only draw 0.1-0.25 amps.
3) while you are experiencing problems, tap or flip the on/off, direction, or any other control switches. From my experience, an intermittent power pack is likely to be caused by a switch that is wearing out.

Thanks, Kevin. I've tried to tidy up my wiring as I realize that if there are a few strands, they can join to the other wire or create an electrical field. Also, my older Triang locos do draw more power (my Hornby Dublo ones from the 1960s draw even more! but I have been running these lately on this layout).

The transformer's serial number is 20509 and its input is 120V, AC 60Hz 125 mA,
Output 19V, AC 0-16V, DC ; total output 7VA. Model number SDK-789.
Here's one for sale on eBay -- <!-- m --><a class="postlink" href="http://cgi.ebay.com/Athearn-Model-Train-Transformer-Power-Control-SDK-789_W0QQitemZ360381879926QQcmdZViewItemQQssPageNameZRSS:B:SRCH:US:102#ht_704wt_878">http://cgi.ebay.com/Athearn-Model-Train ... _704wt_878</a><!-- m -->
Maybe I should buy an extra one!

I've spent the last two night soldering various pieces of track as that has definitely been part of my problem. They layout is now several years old and some of the unsldered sections of track are acting up. I think the wiring is OK -- it's just that some track sections need fixing.

As to the transformer, it still seems that I have to crank it up near its "maximum" point (around the 80-90 mark) to get the trains to run at a moderate speed, even my almost brand-new locos. However, on the other/older transformer, the same trains will go at a moderate speed with the throttle in the half-way or moderate position (hope this makes sense).

Thanks!

Rob

[ezdays]

Rob,

All DC power packs have to convert AC into DC. They usually do that using diodes. The better ones will use a full-wave bridge which is four diodes and a capacitor, others use a half-wave with only one diode and a bigger capacitor. If one diode shorts our, or if one opens in a full-wave, you'll get AC instead of DC. Check out my tutorial on power packs here:
http://www.the-gauge.net/forum/viewtopic.php?f=23&t=627

If you have a meter, set it to read AC and look at your DC output. If you get a rather large voltage reading, then this could be the problem. DC motors don't work that well if you have an AC component riding on the DC.

[pgandw]

The transformer's serial number is 20509 and its input is 120V, AC 60Hz 125 mA,
Output 19V, AC 0-16V, DC ; total output 7VA. Model number SDK-789.
Here's one for sale on eBay -- <!-- m --><a class="postlink" href="http://cgi.ebay.com/Athearn-Model-Train-Transformer-Power-Control-SDK-789_W0QQitemZ360381879926QQcmdZViewItemQQssPageNameZRSS:B:SRCH:US:102#ht_704wt_878">http://cgi.ebay.com/Athearn-Model-Train ... _704wt_878</a><!-- m -->
Maybe I should buy an extra one!

As to the transformer, it still seems that I have to crank it up near its "maximum" point (around the 80-90 mark) to get the trains to run at a moderate speed, even my almost brand-new locos. However, on the other/older transformer, the same trains will go at a moderate speed with the throttle in the half-way or moderate position (hope this makes sense).

Thanks!

Rob

Rob

The 7VA (VA = volts times amps) rating is too wimpy for older locomotives. It translates to a maximum of slightly more than 0.5 amps at 12 volts. It certainly won't handle the load of throwing a switch machine (typically 1-2 amps) without choking eventually. The rheostat (the part that controls the speed) is probably cooking under the load of your engine and any lighted cars, and can/will eventually fail. I had an old AHM train set power pack with a similar rating that went down that road. I was able to salvage the power pack by using the AC terminals as a power supply for a transistor walk-around throttle I built. This didn't improve the output rating of the power pack, but did make a nice throttle for my better locomotives.

As I have gotten more experienced, I refuse to put up with locomotives drawing more than 0.6 amps. The mechanism needs tuning or the motor needs new magnets or replacement if the current draw is that high. An ammeter is a great tool for base-lining locomotive performance and tuning mechanisms.

In the meantime, use the Railpower power pack for your older trains. It has a much larger power rating, and MRC built them with sturdier components than the typical train set power pack.

my thoughts, your choices
Fred W

[RobertInOntario]

The 7VA (VA = volts times amps) rating is too wimpy for older locomotives. It translates to a maximum of slightly more than 0.5 amps at 12 volts. It certainly won't handle the load of throwing a switch machine (typically 1-2 amps) without choking eventually. The rheostat (the part that controls the speed) is probably cooking under the load of your engine and any lighted cars, and can/will eventually fail. I had an old AHM train set power pack with a similar rating that went down that road. I was able to salvage the power pack by using the AC terminals as a power supply for a transistor walk-around throttle I built. This didn't improve the output rating of the power pack, but did make a nice throttle for my better locomotives.
As I have gotten more experienced, I refuse to put up with locomotives drawing more than 0.6 amps. The mechanism needs tuning or the motor needs new magnets or replacement if the current draw is that high. An ammeter is a great tool for base-lining locomotive performance and tuning mechanisms.
In the meantime, use the Railpower power pack for your older trains. It has a much larger power rating, and MRC built them with sturdier components than the typical train set power pack.
my thoughts, your choices
Fred W

Thanks, Fred. This is really helpful. The LHS who sold me the Athearn one assured me it was one of their better, most reliable transformers! When I first bought it, it did provide a fine range of speed so that my locos could creep along nicely at very slow speeds (both old and new). However, I do seem to have to crank it up more now.

Based on the above, what would be a good transformer for me to use, since I run a mixture of old & new locos on my layouts? Shall I stick with Railpower or are there other/similar ones? The Railpower ones were affordable yet I'm not sure if they're readily available these days.

Also, maybe I should use the Railpower one for the turnout rather than the Athearn one?

Thanks again,
Rob

[BR60103]

Rob:
All I can say is that most of mine are in 2 parts: an old Lionel transformer and a separate throttle. The big one claims 90 watts and I think the smaller ones are 40.
The throttles have some what lower ratings. (I would say that 25 watts (or volt-amps) and 2 amps rating on the throttle should be enough.)

[pgandw]

Thanks, Fred. This is really helpful. The LHS who sold me the Athearn one assured me it was one of their better, most reliable transformers! When I first bought it, it did provide a fine range of speed so that my locos could creep along nicely at very slow speeds (both old and new). However, I do seem to have to crank it up more now.

Based on the above, what would be a good transformer for me to use, since I run a mixture of old & new locos on my layouts? Shall I stick with Railpower or are there other/similar ones? The Railpower ones were affordable yet I'm not sure if they're readily available these days.

Also, maybe I should use the Railpower one for the turnout rather than the Athearn one?

Thanks again,
Rob

In general, MRC DC power packs are pretty good. You want a minimum output of 15VA or watts (both are the same for our purposes) to run a mixture of trains. You also need a transistor-type throttle, not a rheostat. Any MRC Tech II or higher with the required output will do very well. Same with the Rail Power 1370, which is listed as a current product on the MRC web site.

Your LHS gave you some serious misinformation. The Athearn power pack was from a train set breakup - I don't believe Athearn ever sold power packs independently. At 7VA, it was designed to power the train set it came with - and nothing more.

For powering switch machines (I'm assuming twin coil - 3 wires - and not Tortoise), the ideal is a Capacitive Discharge (CD) unit. Circuitron makes one, or you can easily build one for less than $10 from on-line circuits as your first electronics project. The CD unit provides a jolt of high energy, just like a camera flash unit. This allows the switch machine (and the switch machine control) to do its job quickly and efficiently without overheating. The CD unit can use a small power pack (12VA or so) to recharge from in about 1-2 seconds. If not using a CD unit for your switch machines, you need 17VA or better for a power source. Even then, your trains will slow momentarily while the switch machine is sucking all the power.

hope this helps
Fred W

[RobertInOntario]

In general, MRC DC power packs are pretty good. You want a minimum output of 15VA or watts (both are the same for our purposes) to run a mixture of trains. You also need a transistor-type throttle, not a rheostat. Any MRC Tech II or higher with the required output will do very well. Same with the Rail Power 1370, which is listed as a current product on the MRC web site.

Your LHS gave you some serious misinformation. The Athearn power pack was from a train set breakup - I don't believe Athearn ever sold power packs independently. At 7VA, it was designed to power the train set it came with - and nothing more.

For powering switch machines (I'm assuming twin coil - 3 wires - and not Tortoise), the ideal is a Capacitive Discharge (CD) unit. Circuitron makes one, or you can easily build one for less than $10 from on-line circuits as your first electronics project. The CD unit provides a jolt of high energy, just like a camera flash unit. This allows the switch machine (and the switch machine control) to do its job quickly and efficiently without overheating. The CD unit can use a small power pack (12VA or so) to recharge from in about 1-2 seconds. If not using a CD unit for your switch machines, you need 17VA or better for a power source. Even then, your trains will slow momentarily while the switch machine is sucking all the power.

hope this helps
Fred W

Fred,

Thanks again. I'm annoyed re that LHS. I recall that this transformer came in its own box, though, and it seemed to be packaged as if it were being sold on its own. At any rate, what you say makes sense & I'll look into getting a better transformer. I guess I'm gradually cooking this Athearn one by running old locos on it & using it for the turnout.

Cheers, Rob

[Russ Bellinis]

I don't know what locomotives you are using with the transformer, but don't discount the possibility that it is the motor in the loco and not a transformer problem. That is why it is absolutely essential to use an ammeter to find out what the load the locomotive is drawing. Open frame motors will build up carbon on the armature segments. As the carbon builds, you get more and more resistance between the brushes and the armature that the transformer has to overcome before the motor starts to turn. If the carbon build up gets bad enough it can also cause a short between segments in the armature. You can spot the carbon buildup with the shell removed because the armature will be black. Fortunately, it is very easy to clean the armature of an open frame motor like the old Athearn models. Just get a #2 pencil with a new eraser, and remove the shell to get to the motor armature. Block the locomotive so that when power is applied, the wheels slip and the locomotive doesn't move. With the motor running full speed, touch the armature with the eraser and move the eraser back and forth until the armature is shiny brass again. Finally after the armature is shiny, shut off the motor, and take your smallest precision, flat blade screw driver, and clean out the black spaces between the armature segments. Give you wheels a good cleaning and also check the contacts where the power is transferred from the wheels to the frame and from the frame to the motor. Make sure that every connection or transfer point is clean. finally make sure your track is clean and all connections are good.

The old style power packs used a wire wound resistor with a slider on the end of the handle. As the handle was moved the slider moved up the resistor and reduced the amount of resistance. The power pack always put out full voltage to the resistor when plugged in and turned on. The position of the slider on the resistor determined how much resistance would be used to reduce the power out put from 0 volts to full voltage. The point of all of this is that resistance reduces voltage. The voltage reaching you r locomotive will determine it's speed, and also how well the locomotive responds to the throttle inputs.

[rrinker]

Those old rheostat packs won;t work with newer, more efficient motors - the rheostat doesn;t have enough resistence. Crack the throttle and the loco will take off. If you rememebr they used to have 2 product lines - one for HO and one for N. Try an N scale loco on the HO pack and it woudl be uncontrollable. Transistor packs don;t have this problem.

7VA is really not much power at all. It's essentially watts, which is volts time amps. At 12 volts, a 7VA pack can only produce a little over half an amp. Fine for modern locos with decent motors in them. My old MRC Tech II was built like a tank, unfortunately they're long out of production and without some facility to truly test it I am leary of used power packs. ANd even if it works, there's always the condition of the line cord. Generally not too much of a problem with 20-30 year old items, but a really big concern with Lionel transformers. A newer current model would be the Tech 4 series. The Railpower ones are better than train set power packs, but not a whole lot more powerful. The Tech 4's are available with 17 to 20VA depending on the model. That's around 1.5 amps, plenty for even the older locos (although maybe not a dual motor Bowser PRR T-1).

--Randy