Kato GP38-2 / GP50 ESU loksound select micro install

[Steveruger45]

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I recently upgraded an old Kato GP38-2 and GP50 to sound.  Both have, more or less, identical chassis.  These were relatively easy to do as the body shell is wide enough for the decoder.  The frame had to be "milled" at the rear shelf and above the motor. I used simple tools only, a junior hacksaw, a file and some patience.  The frame metal is really soft.  Basically file out above the motor and between the four screws which hold the metal chassis to the plastic lower part of the frame and these screws also hold on the electrical pick-up pieces.  Cut off the light shield on the rear shelf and file the rear shelf down about 1mm.
I used 16 x 9mm speaker in a roll-your-own enclosure and put the 2 x 220uF 25v keep alive caps behind it. The lights are made by soldering an smd 1Kohm resistor directly to a similar sized soft white smd LED and then connecting up these "light units" to the respective wires. The "light units" are glued to scrap styrene for support. After insulating the caps connections I glued the rear light assembly in between the caps connections with a drop of CA.  Similarly with the front light assembly.   As these frames are not split like most newer locos the two left side screws have insulated tubes. You need to electrically connect the two left side screws together to get electrical pick-up from both truck sets. You dont have to do this on the right side but I did anyway. To get electrical supply to the decoder I used the original dc light board, which I cut into four small squares and drilled a small hole in the middle of each, for the screws to go through.  These act as both a frame insulator and electrical connection points for each of the four screws that hold everything together. A small length of wire is soldered between the fwd and aft screw tabs, one on each side.
On the GP38-2 I also fitted some scrap styrene under the four screw heads, I omitted this on the GP50 as found it unnecessary.

[RBrodzinsky]

Very nice!

[Steveruger45]

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Thanks.  Here are a couple of photos of the frame "milling" needed on these.
Steve

[Jbub]

Ah! The elusive 25v 220uF caps that I can't seem to find. Where did you get them?

[Steveruger45]

On Evil Bay.  They are "generic" non brand and from China and not expensive.
Quality seems ok too.  At least I have had no explosions so far.
However,  my NCE system only pumps out 13.8 volts max.
Here is the link.
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F322335555830
Steve

[Steveruger45]

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F322335650799

Oops here is the correct link for the 220uF 25v caps.
The earlier link was for 440uF 16v caps

[peteski]

Those locos are one of the last ones made utilizing lead or lead alloy for the chassis. That is why the metal is so soft and the extra mass gives them good pulling ability.

As far as the inexpensive tantalum capacitors go, I highly recommend giving them a "burn in" before installing them in a model. Basically hook them up to a source of DC voltage (of roughly 80% of their rated voltage) for few hours (make sure the polarity is correct) because they probably aren't screened during manufacturing. That should weed out any bad apples and greatly reduce the risk of flaming caps inside your model.  I have a variable voltage power supply for that.

But I guess in a pinch pair of series-connected 9V batteries should do the trick (18V total).  Do not use a standard model train throttle. The peak-to-peak ripple of the unfiltered DC on the output will most likely be exceeding the cap's voltage rating. And the rheostat (speed control) will not reduce the voltage since there is no load on the output (the cap creates momentary load when charging then it doesn't consume any current.

[Jbub]

Those locos are one of the last ones made utilizing lead or lead alloy for the chassis. That is why the metal is so soft and the extra mass gives them good pulling ability.

As far as the inexpensive tantalum capacitors go, I highly recommend giving them a "burn in" before installing them in a model. Basically hook them up to a source of DC voltage (of roughly 80% of their rated voltage) for few hours (make sure the polarity is correct) because they probably aren't screened during manufacturing. That should weed out any bad apples and greatly reduce the risk of flaming caps inside your model.  I have a variable voltage power supply for that.

But I guess in a pinch pair of series-connected 9V batteries should do the trick (18V total).  Do not use a standard model train throttle. The peak-to-peak ripple of the unfiltered DC on the output will most likely be exceeding the cap's voltage rating. And the rheostat (speed control) will not reduce the voltage since there is no load on the output (the cap creates momentary load when charging then it doesn't consume any current.

Pete, I don't care what others say about you. I like you and you always have some useful tip on electronics (and almost everything else for that matter)
Thanks
Oh and thanks @Steveruger45 that helps immensely!

Jbub

[Steveruger45]

Peteski, great idea. Could possibly use a charged up 18v power tool battery. I will give this a go.
Steve

I just did as per photo.   

Would a 2 hours be enough?

[peteski]

Pete, I don't care what others say about you. I like you and you always have some useful tip on electronics (and almost everything else for that matter)
Thanks
Jbub

LOL, you made my day!  I also supply snarkiness at no charge! 

[peteski]

(Attachment Link) Peteski, great idea. Could possibly use a charged up 18v power tool battery. I will give this a go.
Steve

I just did as per photo.   

Would a 2 hours be enough?

That is an excellent idea Steve!  Yes, couple hours should be plenty of time.  I would expect the failure to occur within the first few minutes, but if you have the time give them 2 hours.  As an added bonus, your battery pack has enough amperage to produce a great light show if a cap goes bad. 9V batteries will probably just make it hot.  You might want to put the cap on a non-flammable surface (like a ceramic tile), sit if ti fails it will nto cause a real fire.  Hopefully it won't be needed, but it is a good precaution to take.

You could also burn-in multiple caps at a time (in parallel, just like you will hook them up inside your model).  You could burn-in a dozen at a time (since they do not consume any current after the initial charge - they only start drawing high current if they fail and turn into heaters. 

[Steveruger45]

Great advice. Am working on a parallel test set up now with my limited equipment.
But I think I will solder a bunch of say six caps in parallel and hook up the wire ends to the battery.
I can always desolder them again as needed for the next project.

[Steveruger45]

I just wish I had a piece of z scale track, then I could line up the caps contacts to the rails and clamp them down with strong-back and hook up the battery to the track.

[Steveruger45]

Peteski, you are a life saver.   I just hooked up seven of my Chinese non branded 220uF 25v caps in parallel and applied the 18v battery.
Three of them blew up immediately. The rest are ok after two hours.  So, if anyone wants to try these caps beware.
Steve

[peteski]

Peteski, you are a life saver.   I just hooked up seven of my Chinese non branded 220uF 25v caps in parallel and applied the 18v battery.
Three of them blew up immediately. The rest are ok after two hours.  So, if anyone wants to try these caps beware.
Steve

Wow!  That is a higher failure rate than what I expected!  Are you sure they were not hooked up backwards?   But yes, a burn-in period (pun intended) is a model-saver.    Also be cautious - I had a red-hot glowing cap that exploded fly by my head like a rocket! Wear eye protection or put a shield in front of the burn-in area.