Spectrum Magnum Ultra Plus transformer

[oldtimer52]

I have an older Spectrum Magnum Ultra Plus transformer that has quit producing variable dc power.  Bachmann
no longer has any schematics or guides for this item as it is over 20 years old.  If anyone here has a copy
of the schematic and/or trouble shooting guide, I would appreciate being able to get a copy.  Also, if you have had this problem and know of a fix, I would appreciate that as well.  Thanks in advance.

George

[richardl]

Can you open the case? No idea of your electrical experience but make sure it is not plugged in. Not a dumb statement as some over the years have attempted to work on mains power devices without unplugging first.

There will be a transformer, rectifier, potentiometer, reversing switch. I see this power pack has momentum and couple meters. Few other components. Get your multimeter out and troubleshoot. Do a continuity check. I have done that in the Past.

I don't think The Powers That Be will allow pictures here. I posted a couple sometime ago about a Bachmann power pack repair and they were removed. Bachmann does not want to be responsible for someone getting shocked.
No doubt, you will have to get pictures via PM.

You might Google,  Spectrum Magnum Ultra Plus transformer. No telling what you might find.

Rich

[oldtimer52]

I appreciate your reply on this.   I have run tests on the AC and Constant DC outputs, and both are putting
out the proper voltages.  Was thinking that maybe the potentiometer may be bad on it.  I completed digital electronics school back in 1978 and have been a computer repair technician for over 30 years, hope this
alleviates your fears about my experience.   If you have pictures, or possibly a schematic, I would appreciate
copies of them.  You can send them to gwynnthreeATcoxDOTnet.   I have had the unit open and the inside is not
very organized, that's why I was looking for a schematic.  The pictures should help on sorting out the mess. 

[electrical whiz kid]

Had the same problem with my MRC Xformer.  Had a bad joint in the circuitry.  These things are pretty straightforward, but like anything else electrical, the devilment will be not [usually be] on anything exotic, like parts; but some dumbo issue like what I had.  If you really want a thrilling  experience, try troubleshooting an aircraft generator (MD-3) on-sight at night (winter season) at like Minot AFB, et al...   Freezing fingers...  WhatFun!

Rich C.

[Len]

I don't own a Magnum Ultra Plus, but have similar power packs with momentum from other manufacturers from that period. One had a similar problem to your's, and what I found was a 'fusable link' on the PC board for the momentum circuit had opened. The amp rating as on the board, so I added a fuse holder accessable from outside the case, and replaced it with a standard fuse.

Then again, with 20 year old electronics it could be many things. From a bad speed control pot to fried transistor.

And all of the manufacturers do the "No user replacable parts inside" warning, and do not publish their schematics for liability reasons. So if you're going to try repairing this, grab a pad and pencil, and start tracing wires and PCB traces.

Len

[richardl]

I would suggest a drawing and maybe pictures of what you find. Might not be able to post them here but could PM them to those who would like to know.
With the Internet, we have a huge MRR community available. Many other train forums also.

Rich

[electrical whiz kid]

Len;
Are you saying that you have a fuse holder ON THE OUTSIDE of the case?  If you do, and you are fusing 120VAC that is one dangerous situation.  NFPA70 uses the term "readily accessible"; which means that where you can install exposed and energized parts.  "Out of reach" means so that it is out of touch for non-qualified personnel.  I know this sounds like a lot of Horse ****, but it will make for a safe install.

Rich C.

[Len]

Rich - No line current involved.

The fuse replaced a fusable link on the "momentum" PC board on the low voltage side of the transformer.

I drilled a hole in the transformer case and mounted a 'panel mount' fuse holder in an area where there was nothing inside for it to interfere with. Then I unsoldered the remains of the fuseable link from the PCB, and installed and soldered wires from where it had been to the fuse holder. I closed it up, installed a fuse to match the fusable link amp rating on the PCB, and was back in business.

Even if it had been a line side fuse, when I was done all that could be accessed with the cap of the 'panel mount' fuse holder. No different than many consumer electrical/electronic products. But like I said, this went to a circuit on the low voltage side.

Len

[jbrock27]

I'm gonna try this again and damn the torpedoes!  Don't know why my initial post was deleted the first time but I have long since given up on trying to figure out why things happen here ...

I have run tests on the AC and Constant DC outputs, and both are putting out the proper voltages.

I am confused ot52, is this or is this not working properly?  If the answer is it is not, then I suggest you don't waste your time or resources further and replace this with a power pack made by MRC.  One of the more modern black plastic case ones.  Plenty available out there, including a huge selection on Ebay.  Even used ones are near bullet proof and worth buying.

I once received a power pack that had one of the AC screws stripped.  After making a special tool to turn the screws in order to get the pack open (at the time I wrote this before, I recall RichG who is now richardl, warning me up and down about not working on it while plugged. Of course, I did not, only common sense).
Anyway, I was able to replace the bad contact screw, but in the process, screwed up (pun intended) the DC side of things.  After ordering a new "pot" and transistor, I found my efforts failed (luckily not after a huge investment of $$).  In the end I used the pack just as an AC source since that worked fine and learned to not make the effort in the future to take such things apart and spend time and $$ on chasing electrical parts down for it.

I hope this helps and good luck

[Len]

jb - The Spectrum Magnum Ultra Plus has three outputs, 1 fixed AC, 1 fixed DC, and 1 variable DC.

Oldtimer is saying the fixed AC and DC outputs are good and putting out the correct voltage. Which means the low voltage side of the transformer would appear to be okay. The variable DC output is dead, which could be a bad pot, broken wire, bad direction switch, etc., etc., that only applies to the variable output.

Len

[Mdaskalos]

jbrock,

I would surmise the reason for deletion is your overt reference to "Mister C's" brand of products.

Anyway, back to the subject at hand:

If it's over 20 years old, and if repairing is your plan, any electrolytic capacitors it has will be a problem, and may be the cause of the malfunction.

Several years ago, a friend of mine who owns an industrial electronics repair business hired me as a repair technician for a couple of months when I was laid off. The first rule he taught me was: Electrolytic capacitors have a life of approximately 15 years whether the component under consideration had been in use or not.

The second rule, based on the first, was: Anything that came into his shop more than 7 years old got all of the electrolytic capacitors replaced, whether that was the cause of the failure or not.

About the time I got regular work again and finished up at his shop, the power amp to my high-end stereo (13 years old at the time - from my bachelor days, when I could afford high-end things) went belly-up . I took off the cover, identified and ordered the "caps", and when they came , I took it to his shop and replaced them all, and it was back working perfectly again. In keeping with his 7-year rule, I did the caps in my pre-amp at the same time, although it was working fine.

But, we're talking maybe $50 of military-grade capacitors to fix a pair of components each costing four figures. Unless your transformer is itself expensive or has unique functionality that will be expensive to duplicate with other components, consider replacing the thing.

Footnote: I have boys that I'm trying to teach a few skills to prepare them for adulthood. Sometimes I'll forego the cheap, quick, & expedient to furnish them a skill-learning exercise through repairing or making something. Considerations like those may enter into your repair or replace decision.

MDaskalos

[jbrock27]

Here we go again; don't know why my response to Len got deleted, but I will try again...

Thank you Len.  Got it.  
I don't have one of these and did not find a reason spend the time to look up its specs, but regardless, the answer to the question is, "yes, it is not working properly".
My suggestion therefore remains the same, replace it with an MRC.  If ot52 wants a direct replacement there are models that have the same features.  If it was me, I would use the Spectrum for its Constant AC and DC outputs and get an MRC to supply the variable DC.

[jbrock27]

jbrock,

I would surmise the reason for deletion is your overt reference to "Mister C's" brand of products.
MDaskalos

MD, I could surmise that as well, but then, should I not see every post that suggests Kadee couplers be removed as well?

...consider replacing the thing.
MDaskalos

So I guess you agree with jbrock?

[electrical whiz kid]

On caps;
Having had devoted most of my natural life to the electrical industry, A couple of things had stayed with me;  one would be yes; electrolytics DO have a life time expectancy; depending upon their quality, and their use.  Some of the comp starting on large motors (like 2300VAC) used tem in their starting wiring, and if the caps were pegging out, then the motor would act kind of funny-like not start.  I have a Craftsman radial-arm saw that I have replaced the capacitor several times.
BROCK:   What are you talking about?  Which kit?

Rich C.

[jbrock27]

Let's not muddy the waters Rich, let's keep that question, which is seperate from this subject, to PMs.  Sent you a PM in response.
Thnx.