Railpower 1300 testing

[Point353]

Even so, 23 isn't 25.  And since decoders aren't dropping dead by the thousands every time they come near one of these power packs, whatever is going on is probably something that is right on the edge of the decoder's tolerance.  It wouldn't surprise me at all to discover that a couple more volts in those pulses is enough to occasionally make these decoders fail (at the 25v mark).

If the failures are (also) happening with HO locos, whose decoders are supposed to withstand at least 27V, then the issue isn't with the power pack.

For N scale, the decoders are supposed to withstand at least 24V and the MRC 1300 puts out 25V (by your measurements back on page 5) only when the throttle knob is fully advanced.

What are the odds, in every case of a decoder failure associated with an MRC 1300, that the user has fully advanced the throttle knob?

Is there some significant delay before a loco with one of the Rapido dual-mode decoders begins to respond which, in turn, might induce the user to turn the throttle knob up all the way because nothing initially appears to be happening?

[mmagliaro]

If the failures are (also) happening with HO locos, whose decoders are supposed to withstand at least 27V, then the issue isn't with the power pack.

For N scale, the decoders are supposed to withstand at least 24V and the MRC 1300 puts out 25V (by your measurements back on page 5) only when the throttle knob is fully advanced.

What are the odds, in every case of a decoder failure associated with an MRC 1300, that the user has fully advanced the throttle knob?

Is there some significant delay before a loco with one of the Rapido dual-mode decoders begins to respond which, in turn, might induce the user to turn the throttle knob up all the way because nothing initially appears to be happening?

I agree, HO decoders should not be failing.

As for the power pack and what the odds are that users are running it full-out - I'd say the odds are pretty good.
Remember, when you run a DCC engine on a DC pack, it won't even start to move until you get over 7 or 8 volts because of the decoder drop.   I've had Athearn engines that absolutely have to be run full-out at 12+ volts on a DC pack just to keep moving, never mind getting up to a medium speed.  I don't know what the drop is on the Rapido engines, but it wouldn't surprise me to find out that people using them on DC packs are running them at full throttle.

[nkalanaga]

"I've had Athearn engines that absolutely have to be run full-out at 12+ volts on a DC pack just to keep moving"

Like my Challenger.... 

[CBQ Fan]

Well, I don’t have my proof of purchase since MBK changed their website and BL wants $79 to fix a unit with less than 20 minutes run time.  I just can’t stomach spending cash on this unit under these circumstances. May be time to look at gutting the whole thing into a dummy unit and run it with my Kato E5’s.

[mmagliaro]

Well, I don’t have my proof of purchase since MBK changed their website and BL wants $79 to fix a unit with less than 20 minutes run time.  I just can’t stomach spending cash on this unit under these circumstances. May be time to look at gutting the whole thing into a dummy unit and run it with my Kato E5’s.

Can't you call MBK and ask them to help you?  They can probably look up your order and send you a proof of purchase receipt.  If you paid by credit card, you can get the credit card statement from whatever month you bought it, even if it was a long time ago.  You didn't run it with one of BLI's "no no" power packs.  You should not have to pay for this.

[Point353]

Well, I don’t have my proof of purchase since MBK changed their website and BL wants $79 to fix a unit with less than 20 minutes run time.

Do still you have the packing slip that would have been in the box?
Or, an e-mail confirming your order?

[Point353]

Even so, 23 isn't 25.  And since decoders aren't dropping dead by the thousands every time they come near one of these power packs, whatever is going on is probably something that is right on the edge of the decoder's tolerance.  It wouldn't surprise me at all to discover that a couple more volts in those pulses is enough to occasionally make these decoders fail (at the 25v mark).

Given that the (N scale) decoders are supposed to withstand up to 24V, would you care to speculate as to what component on the decoder could possibly tolerate 24V but suddenly fail  when 25V is applied? That seems to be a very narrow margin.

[CBQ Fan]

I appreciate the suggestions.  BLI has confirmed it will be a warranty repair so the unit is all packed up and will get shipped tomorrow. Excellent customer support and service! 

[peteski]

Given that the (N scale) decoders are supposed to withstand up to 24V, would you care to speculate as to what component on the decoder could possibly tolerate 24V but suddenly fail  when 25V is applied? That seems to be a very narrow margin.

If the decoders are really blowing up (I would like to get my hands on one of those fried ESU decoders), I doubt the answer is as simple as 1 Volt.  I feel there are several variables at play (depending on a specific circumstances).  Variable component quality might be one important factor.  Some might be at the low range of their specs, others at the high end.

As for the components, It could be rectifier diodes, tantalum caps, internal voltage regulators, or possibly few others.  You might ask, why not use components rated at higher voltage?  Well, my answer is that those might cost more money, and the big one is "how high to go?".  After all, N scale DC model trains are usually rated for up to 12 or 14VDC.  Who is to blame if DC throttles from certain manufacturers produce much higher output voltage?

I have repaired a damaged decoder in the past, but it was not voltage related.  It was likely caused by a short in the motor circuit.  I also just received a blown MRC sound decoder which was supposedly damaged by a DC throttle.  I have not had a chance to examine it, but a quick evaluation revealed that its wiring harness was pretty much melted (causing crossing wires to short out).

Besides, this entire thread is based on speculations. Well, we know that certain throttles do produce fairly high track voltages, but no casualities have been examined here.

[reinhardtjh]

As for the components, It could be rectifier diodes, tantalum caps, internal voltage regulators, or possibly few others.  You might ask, why not use components rated at higher voltage?  Well, my answer is that those might cost more money, and the big one is "how high to go?". 

Components with higher voltage ratings might also be bigger and, for N-Scale at least, we are all usually demanding decoders get smaller.

[Point353]

If the decoders are really blowing up (I would like to get my hands on one of those fried ESU decoders), I doubt the answer is as simple as 1 Volt.  I feel there are several variables at play (depending on a specific circumstances).  Variable component quality might be one important factor.  Some might be at the low range of their specs, others at the high end.

As for the components, It could be rectifier diodes, tantalum caps, internal voltage regulators, or possibly few others.  You might ask, why not use components rated at higher voltage?  Well, my answer is that those might cost more money, and the big one is "how high to go?".  After all, N scale DC model trains are usually rated for up to 12 or 14VDC.  Who is to blame if DC throttles from certain manufacturers produce much higher output voltage?

I have repaired a damaged decoder in the past, but it was not voltage related.  It was likely caused by a short in the motor circuit.  I also just received a blown MRC sound decoder which was supposedly damaged by a DC throttle.  I have not had a chance to examine it, but a quick evaluation revealed that its wiring harness was pretty much melted (causing crossing wires to short out).

Besides, this entire thread is based on speculations. Well, we know that certain throttles do produce fairly high track voltages, but no casualities have been examined here.

Rapido seems absolutely certain that the issue is voltage related when they make the statement:
"Do NOT use MRC 1300-series DC controllers with any of Rapido’s locomotives. The RailPower 1300 is notorious for voltage spikes and it WILL destroy your locomotive. There is no “if” about it."
https://rapidotrains.com/support/

Note that Rapido applies this advisory about the MRC 1300 series to both their HO and N scale locos.
If HO decoders are supposed to withstand at least 27V and the peak voltage measured from the power pack is 25V, then where is the problem likely to be?
Why the ongoing reluctance by @rapidotrains  to further address this matter and/or discuss the observations made throughout this thread?
Their lack of response is becoming the major factor in my decision whether or not to ever buy any (more) of their products.

[peteski]

Why the ongoing reluctance by @rapidotrains  to further address this matter and/or discuss the observations made throughout this thread?
Their lack of response is becoming the major factor in my decision whether or not to ever buy any (more) of their products.

At this point I would not expect any official response from Rapido in this thread.  Just my opinion.

[mmagliaro]

Given that the (N scale) decoders are supposed to withstand up to 24V, would you care to speculate as to what component on the decoder could possibly tolerate 24V but suddenly fail  when 25V is applied? That seems to be a very narrow margin.

No, I cannot speculate on that.  And there's no point to the speculation anyway.  Components don't have to fail within a 1 volt margin to cause this.   What if there is a failing part designed to withstand 25v, but some percentage of them are simply not quite up to spec?  Consider electrolytic caps rated at 25v.  Yes, some of them can be run well above that.  And... some from the same lot might fail at 26v.

I've done about all I can do with this.  Whose "fault" it is cannot be determined unless the manufacturers involved here are really interested in doing repeated experiments on the actual products.  I cannot do that.

All I'm prepared to say is that 25 volt pulses in a power pack are completely unnecessary, and they are high enough that I would start worrying about what they might do to sensitive electronic components and even motors, so I would avoid them.  I provided circuit mods (along with Peteski's help!) to achieve that easily and cheaply in the 1300.   I am done speaking on the subject.

[Point353]

I haven't had time to draw up the schematic yet.  But I can tell you this, there is a transformer, 4 diodes, one resistor,
and one Darlington power transistor, plus the speed control pot.  That's it.  There's no filtering, no caps.

There is a Polyfuse in there for overload protection, so all you would have to add to get an "overload light" would be 1k ohm resistor and LED wired across that Polyfuse.  The LED would light any time the Polyfuse "opens".  And I know this because I've used that exact same trick myself 100 times for an overload light.  (Okay, not 100, maybe like, 12, but...)

I forgot I hadn't posted the 1300 scope pics.  Here they are:

When you performed these tests, do you recall what was the value of the AC line voltage?

[mmagliaro]

I did not measure the AC line voltage from the wall when I did these tests.