MRC Pure Power Dual Transformer Issue

These transformers have an internal fuse- in your case two fuses. Its possible that you blew the fuse before the c.b. tripped. 

If the screws holding the transformer casing are not of a common type, you may have to send it back to mrc for fuse replacement.

@prrhorseshoecurve posted:

These transformers have an internal fuse- in your case two fuses. Its possible that you blew the fuse before the c.b. tripped. 

If the screws holding the transformer casing are not of a common type, you may have to send it back to mrc for fuse replacement.

Wonderful. I'll peak at the underside and see what kind they are. Btw, I should've mentioned. I use both DCS and legacy. 

I don't remember any fuses in the AH601.  The fact that power returns when you hit the direction key "the right way" suggests something has gone wrong that's not a fuse internally.  You'll have to open it up and look, they're actually a very simple transformer.

Got her open. What should I be looking for? 

Following with interest, as I have one where one side is completely dead.  Hoping for a simple fix.  Thanks in advance.

@Mallard4468 posted:

Following with interest, as I have one where one side is completely dead.  Hoping for a simple fix.  Thanks in advance.

Is it the same issue I'm having? Or something different? 

Remove the boards with the diodes and yellow plastic strips on the left side. Flip it over and check all three copper tabs very carefully where they are soldered to the board. Look for failed solder joints and broken contacts. This is a known issue with these transformers. I have the PP Dual and the PP. Both of mine have had this failure and replacing the tabs on one and resoldering a tab on the other took care of the issue. MRC has the tabs in stock. If you want to fix it yourself, contact them and they will send the tabs to you. I got three tabs for about fifteen bucks. I only replaced the tab that broke instead of all of them as they suggested. No point in replacing parts that haven't failed yet. They will fail later and you'll have some spares. If you don't press them too hard, which is difficult because they are stiff and don't have the familiar 'click' when they are pressed, then the chances of them failing are greatly reduced.

What he said.

@Trainlover9943 posted:

Is it the same issue I'm having? Or something different? 

Similar, but possibly with a slight difference.  As far as I remember, one side of mine is completely dead - don't get anything by pressing the reverse button.  But I also don't know that I tried that.  Other side works perfectly.

Mallard, advise for you is the same I gave to TrainLover. I am almost certain you have a failed contact.

@Mike D posted:

Remove the boards with the diodes and yellow plastic strips on the left side. Flip it over and check all three copper tabs very carefully where they are soldered to the board. Look for failed solder joints and broken contacts. This is a known issue with these transformers. I have the PP Dual and the PP. Both of mine have had this failure and replacing the tabs on one and resoldering a tab on the other took care of the issue. MRC has the tabs in stock. If you want to fix it yourself, contact them and they will send the tabs to you. I got three tabs for about fifteen bucks. I only replaced the tab that broke instead of all of them as they suggested. No point in replacing parts that haven't failed yet. They will fail later and you'll have some spares. If you don't press them too hard, which is difficult because they are stiff and don't have the familiar 'click' when they are pressed, then the chances of them failing are greatly reduced.

 

I took it off and didn't notice anything wrong. Of course I may not have been looking hard enough. 

Okay, sorry. You have to remove the yellow plastic bar. I think it has four screws in it. the traces are on the other side of the board. the picture you have is of the bottom of that board. BE CAREFUL when removing the plastic bar. There are three springs in there that keep the tabs in place. It is not bad, but if you aren't used to working on this kind of stuff it can be a PITA.

When I looked more closely at the first picture, it looks like the contact on the right is detached from the board.

If it is just a failed solder joint and the metal isn't actually broken, you should be able to reflow the connection and be good to go. That is how I repaired one of mine. The other one had the contact actually broken in two.

Got it off. Looks like the one for the direction key need to be resoldered as it popped off when I took the strip off. 

Fixed. Wonder how that tab got unsoldered? 

@Trainlover9943 posted:

Fixed. Wonder how that tab got unsoldered? 

Flexing or a cold solder joint from the factory.  I see a lot of that in brass locomotives, the solder joint seem to crack and lose strength with age.

I purchased one of these to replace my Z4000 which I believe needs the potentiometer replaced. I would like to get that fixed eventually. The right throttle of the MRC seems to have a similar issue as mentioned here. It worked fine at first but after multiple uses it became unreliable. Since I don't run conventional I leave it on full power and just turn it on & off with the rocker switch & power strip. So far so good. 

The throttle on these are usually almost bulletproof.  They go directly to a really large carbon wiper on the toroidal transformer coil.  I can't imagine it being a high failure item.

Be that as it may. Some times I move the throttle forward no volts, possibly the plastic handle is slipping on the stud. I'll check that since I have no intention of opening the thing.

Hi Folks,  My PPD amp gauges don't work.  Just wondering if anyone can tell me what to check for.  Thanks for your thoughts.  George

Looks like there is a lot of play in the handle, not sure if that's where the problem is or was. It seems to work fine at the moment. Unless someone suggests that its not a good idea to leave it in the full position, I'll keep it that way.

When I had one of these, I left it full throttle for a couple years, didn't hurt it any.

Thanks John!

The left side of my transformer went dead after pushing the directional button, but after sever pushes, it came back to life.  I put a piece of tape over it so I wouldn't push it again until a couple days ago. Oops !

Thanks to you guys and this thread I got the courage to open it up and knew what to look for.       Here are a couple pictures; 

The first thing I noticed was the copper tab catching on the wire, upper right, but it hadn't worn through the insulation, so I bent the wire out of the way. 

After removing the yellow plastic cover, sure enough the solder joint for the tab had come loose. 

Now off to Harbor Freight for a soldering gun,  I guess a 25 watt will do the job ? 

Doug

@boomer0622 posted:

The left side of my transformer went dead after pushing the directional button, but after sever pushes, it came back to life.  I put a piece of tape over it so I wouldn't push it again until a couple days ago. Oops !

Thanks to you guys and this thread I got the courage to open it up and knew what to look for.       Here are a couple pictures; 

The first thing I noticed was the copper tab catching on the wire, upper right, but it hadn't worn through the insulation, so I bent the wire out of the way. 

After removing the yellow plastic cover, sure enough the solder joint for the tab had come loose. 

Now off to Harbor Freight for a soldering gun,  I guess a 25 watt will do the job ? 

Doug

I used an Xtronic soldering station (3020) from Amazon to solder my tab but I also have a weller soldering gun. Once upon a time I had both the iron and gun from HF and threw them both away. They were junk. 

It looks like they're only about $5.  so if it works once for me I'll be happy. 

@boomer0622 posted:

It looks like they're only about $5.  so if it works once for me I'll be happy. 

Good luck. 

I got it fixed after a couple try's,  with the first attempt I reattached the tab with too much clearance between the tab and the contact and the spring would not hold it down far enough.  So I resolder it and now it works fine. 

Ironman1,  While having the transformer open I noticed a couple set screws that hold the brush arm onto the shaft.  Maybe that's the problem with the handle moving and no voltage increase, the shaft is slipping. 

@Mike D posted:

If it is just a failed solder joint and the metal isn't actually broken, you should be able to reflow the connection and be good to go. That is how I repaired one of mine. The other one had the contact actually broken in two.

@Trainlover9943 posted:

Got it off. Looks like the one for the direction key need to be resoldered as it popped off when I took the strip off.

@Trainlover9943 posted:

Fixed. Wonder how that tab got unsoldered?

It only took a little less than 2-1/2 years, but I finally got around to taking another look at it.  Broken solder joint on the tab for the direction button.  I had opened it up several years ago, but the broken joint was not really visible - had to move the tab to notice it.

Resoldered it and... success!  The little screws that hold the spring bar in place are a PITA, but thanks to all the info here I was prepared for them.  This was possibly the easiest soldering repair I've ever done.

Thanks to all who contributed to this thread - I couldn't have done it without you.