What's inside those Power "Bricks?"

[peteski]

That Bachmann unit you reviewed sure uses a very esoteric design I have never seen before.  Needlessly overcomplicated with no added benefits that I see.

[$2 Bill]

That Bachmann unit you reviewed sure uses a very esoteric design I have never seen before.  Needlessly over complicated with no added benefits that I see.

When you see stuff with weird wiring & such is often to Patent a device OR to bypass Patent(s) from others.

What gets me is 2 Breakers in series. I can't see Part # or other marks for them to see same or different values but make little reason. Plus 2 Polly Fuses.

Output to Trains seem Current "Regulated" but not sure just what/how over or no current acts. Maybe the Resistor is too high Ω to test But believe the unit is "Dead" as noted before. So I'm still watching Flea markets etc for another unit.

Maybe this Unit & similar from Bachmann is "Safe" for Coreless Motors now common for N & other tiny trains but even then 2 breakers make no sense.

[mmagliaro]

I have two comments on that odd Bachmann circuit design.
First, I'd ask you to double check that PCB to see if there is anything connected BETWEEN the two thermal fuses.  There appears to be a trace on the board going under one of them in the middle (on the left side of the board) and then snaking off and around down to R2, among other places.  There could be a reason for having two.  I seriously doubt they just put two breakers in series.

Second, as to the design of having two power transistors, one for each polarity, have to you tried flipping the direction switch
while the throttle is up to see how the circuit reacts?  It's hard to tell just from looking at the schematic, but maybe using the two
transistors creates a circuit that will gradually ramp down and back up in the opposite direction without jarring the train.

[$2 Bill]

Bachmann 46605A & related are 1 sided PCB & Parts are often used as "Jumpers."
Fuse 2 jumps over the trace for D1 & D2 1N5401. D1 & D2 also "jumps" traces but on the other side.
Edit--> The trace that "Goes under" Fuse 1 is the same one as Fuse 2 Jumps. IE Just connect those Diodes to "bottom" end of Fuse 1.
Blue follows the trace for the Diodes, Red Fuses. (Breakers are Riveted & solder to the board so not taking them off.)
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There is Nothing between Fuse 1 & 2. Look at pic for Transistors. Just right is D1 but nothing else on "back" of PCB there.
Edit--> second view "Back" of PCB
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As said before the unit is "Dead" & now lost too. (then found again for 2nd pic) Doubt the unit will "soft switch" the direction but if/when I find a "new" one I'll test this.
Can't find the PDF in manual right now. Thought said stop before changing direction like most others.

[$2 Bill]

Second, as to the design of having two power transistors, one for each polarity, have to you tried flipping the direction switch
while the throttle is up to see how the circuit reacts?  It's hard to tell just from looking at the schematic, but maybe using the two
transistors creates a circuit that will gradually ramp down and back up in the opposite direction without jarring the train.

Can't find a Bachmann PDF say much or anything for train direction.
Example: https://www.bachmann.co.uk/dbdocument/1019/36-565%20-%20Bachmann%20Train%20Controller%202018.pdf

So went to garage to look in the box to get Printed copy of EZ Track System that came with the "dead" unit.
Only Says...

To change your locomotive's direction, turn the speed controller to the "OFF" position and slide the switch to the left or right as needed.

Page 7 in doc TRAIN-IS121.

I don't see any "timing" to auto fade the speed by switch direction without bothering the knob. The "big" C1 C2 just smooths DC Ripple coming from D1 & D2.
But I'll check the idea maybe with a "junk" engine not just the resistor.

[peteski]

I don't see anything in that Bachmann circuit which would facilitate a gradual slowdown before reversing direction. I still shake my head about the squirrely circuit! It reminds me of those Rube Goldberg contraptions.  And each direction is powered by a half-wave rectifier (single diode) with a 1000 µF cap to smooth out the serious ripple.

[$2 Bill]

Yea, is weird.

Only Guess for Fuse2 is a "Throw Away" part to automate board build. Some times is cheap to "waste" a part so board fits given space or even work @ all then load whatever in pick & place machines, add inventory, etc.

1 or Both Polly Fuses is likely to Pass UL CE & other Testing.

Same box have different Cat No's for Other Counties with correct "Wall Wart," Safety & other Certs. UK & EU uses Different Plugs for 240VAC & deal with TUV etc.

[$2 Bill]

She posted another Hornby model today... HM2000 that uses SCR not a Power Transistor to set speeds.
Note says SCR &/or Tiny Transistor likes to fail. Maybe partly because SCR has a heatsink but installed to block airflow over that.

Hornby HM2000 Model Train Controller Repair

[$2 Bill]

MRC Railpower 1370 Believe built 1995 or later from date code on the PC.

Look the "Same" as MRC Railpower 1300 but isn't. What it is an upgrade to the lower number with heavier Transformer & TIP-142 10 A, 100 V NPN Darlington. Plus the "nice touch" has LED to show the Main Switch & thus PC is On. LED isn't a Monitor Light like Green Light in Tech2 1400 & related.

Front...
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Back of Both... Look @ VA ratings.
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Inside as built... There's nothing hold the guts in place except clamping force in the case parts with 4 screws & the Speed Knob. Only thing "welded" to the case is the LED.
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Top of PC...
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No Schematic but Important Parts are ID'ed. Only reason to take apart this unit for the pic because Direction Switch needed Cleaning to work right.
PC is way more complicated then 1300 with "drivers" between the POT & Power Transistor but Output Power to the Track is same as "cheap" Bricks without Pulse Power of any kind.

100% 17V Peak 13.5V RMS
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50% 8.5V Peak 6.9V RMS
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25% 3V Peak 2.6V RMS
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15% 1.5V Peak 0.37V RMS is ~ where I got readable trace from 0% & 0V.
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While the Board Design might stop some power surges & other issues getting thru... Like many others the unit could kill some DCC units because Peak Volts are already High @ top speeds.

[Point353]

MRC Railpower 1370 Believe built 1995 or later from date code on the PC.

100% 17V Peak 13.5V RMS
(Attachment Link)


While the Board Design might stop some power surges & other issues getting thru... Like many others the unit could kill some DCC units because Peak Volts are already High @ top speeds.

Are those the "spikes" which Rapido Trains was alleging were damaging the dual-mode decoders used in some of their locos?

[mmagliaro]

Are those voltages at no load, or did you have a small load on it?
Back in 2018, I tests a 1300, and saw fully 25V peaks at full throttle.  So 17 for the 1370 ain't bad by comparison.

And Point353, in reply to this question:
"Are those the "spikes" which Rapido Trains was alleging were damaging the dual-mode decoders used in some of their locos?"

Yes, Rapido's statement said "1300 series" Railpower, so I assume they meant both the 1300 and 1370.   25v peaks from the 1300
really gave me agita, hence the small wiring change I published in here to cut it down.  I would not expect 17v to damage anything.
If they are using 16v caps, or something like that, I'd say that's a bad idea.

[peteski]

For reference, here is a link to a lengthy discussion of that Railpower 1300 pack blamed by Rapido Trains for blowing  ESU decoders, Max's evaluation of the power pack, and his simple way to lower power pack's output voltage.   Hard to believe that was eight years ago.
https://www.therailwire.net/forum/index.php?topic=44170

[$2 Bill]

All Test are done with same 120Ω 15W power resistor to keep noise etc from a train cause other issues. (@ 15V draws < 0.13A so doesn't need 15W...) Note: "RMS" Volts may not be the same between different Meters even if label as "True RMS." Many to all "Vintage" Meters expect clean Sine Wave & often < 100Hz. "True RMS" claim doesn't care about shape or Hz but programing is often different may charge the Final/Display Volts. I use same "Pro" Craftsman meter for all test for that reason.

I've lost count of what page(s) or site(s) Rapido states isn't just MRC 1300 & 1370 but any old "Bricks" can fry the decoders. I've seen other DCC manufactures "hating" any to all DC packs too. The "war" with Rapido is a Direct Result of MRC claiming BS & "Not their problem" from 130x or any other DC models.

The Peak Power as shown here & other places is 1 part that could kill DCC units when the Peaks are Too High. Many Packs in this thread alone have Peaks just @ top of the range of safe use or just above that.
1300 I test was just under 20V Peak before it died as noted. Other may test 1300 etc with more Peaks or RMS volts for many reasons including Local Mains are a bit Higher then 120/240VAC. 1370 Peak is a bit above "Safe" according to Rapido & others manufactures. (240VAC? Because UK EU & more runs that to everything not just some loads like Electric Stove But Train & more packs are same otherwise.)

As said in other posts...

What Killed DCC thing on DC may not be the actually Power Pack but all of the Crap on 120VAC side "Blowing Thru" the Pack. Most People have Little to No Clue how "Bad" the main power often is. Noise, Spikes, Surges, & more problems just passes thru a basic Transformer & many Filters like a big Capacitor. These problems Can "blow thru" many Switching PSU too depending just how there designed/made vs type & magnitude of the problem.

Those Terms often mean Time not just Volts. Spikes can last Milliseconds & Volts could be Hundreds to Thousands while Surges can last Many Seconds but often < 2 to more times over Nominal Volts. Vs Noise is often a little over Nominal Volts but may Never Stop. Most Strips block the First & maybe Second & ignore the Third.

"Extreme" Example: Many UPS & power Strips have a "Lifetime" Warranty protecting whatever is plugged downstream including many APC(APCC) & Tripplite products... If Lightning hits your House or Near By, Nothing is going to stop the Surge from Flashing thru the UPS/Strip or any or all downstream of those parts. I've worked IT @ Retail & "Fortune 500" & bigger Companies & replace/fixed a lot of things after many Lightning Strike to see this happen many times. Wind in any Storms can Majorly Spike Power too as High Volt wires hit or get hit by Trees etc. causing same results.

But Even "Large" motors like in refrigerators in your house can cause spikes etc big enough to fry many electronics not just DCC stuff. This is Part of why Current Code in the US & some other Counties require Surge Protection In The Load Center AKA Breaker Box / Consumer Unit. To make those last long, many "eat" only the worse spikes, often > 500V. Vs many UPS/Strips protects starting @ 330V spikes in N. America in 120VAC Branch lines.

If you compare DC or Many DCC packs to Brand Name PC PSU (Desktop or Mobil) the PC PSU often have way more protection from Noise, Spikes & related issues on 120/240 side & why many times you see power issues in you lights but PC doesn't crash every time the lights Brink Off or Flash Brighter.

That's a problem but even with "Pure" Power You can kill or crash many things by Static. Example: Maybe Why some DCC decoders loose the settings @ random as Static wiped Flash RAM. "Worse" Static most see is often in the Winter with Very Dry Air but Static never shock you can fry/crash electronics. Or Static doesn't kill whatever right now but next time using it the power finish the job & maybe way obvious damage then & magic smoke come out... This is Why Companies spend Thousands to Millions of $ just for "Static Safe" work areas to make many products.

[$2 Bill]

I was bored last night so made a Schematic from the pics of the 1370 to see exactly how the extra Transistors are used.
I also looked for the "Manual" to make sure isn't a "pulse" setup that "failed" for that section. Google found it @ MRC site... While many old "Manuals" are hidden/berried there,  "Sadly" both 1300 & 1370 models are still in stock as a "cheap option" so maybe I shouldn't post the Drawing?
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In short, those are not a "Driver" as quick thinking for above post for the POT but Current Monitoring.
The POT runs the TIP142 Q3 direct but via R2 270Ω (R2 is next to Blank spot of R1.) & this "shorts out" the small Transistors to "drive" Q3. The other parts are there to Monitor R2 & shut off Q3 for Overload.

Side Note: 2N2907 2N3906 & related Part No's often say Discontinued... Any "Jelly Bean" PNP will work there. Current version of both can be easily switch to Surface Mount parts without redesign the circuit.

To save time to post, I tried Google Image search & gave it just the schematic without anything else to get this "easy to read" text...

4. Overcurrent and Short-Circuit Protection
The network involving transistors Q1 (PN2222A) and Q2 (2N2907) forms an active current-limiting protection loop:
▪Current Sensing: The voltage across specific resistors changes depending on the load current.
▪Feedback Mechanism: If a short circuit occurs or the current exceeds a safe threshold, Q1 and Q2 turn on.
▪Shutdown: When activated, this protection network pulls down the base voltage of Q3, shutting it off or restricting its output to protect both the throttle circuit and the model train motor.
▪Time Delay: The capacitor C1 (10μF) provides a small time constant to prevent temporary startup current spikes (like a motor starting up) from accidentally tripping the protection.

So to correct/adjust the 1370 "Review..."
If you find or buy Railpower 1300 or 1370 for a DC layout, you may want the 1370 over the 1300 & many other DC packs because it adds more Overload protection. But If this second piece "Trips" for any reason then the LED may Not Turn Off like the PTC does when that "trips" as stated in the "Manual." IOW Maybe "Better" with 1370 when you put a Engine with issues on the track that draws way more power.

Nothing Change for DCC on DC. Even if a DC Pack is "Safe" to run DCC per Rapido et al Specs, Little or Nothing is going to block problems from 120AC side getting @ DCC or other Electronics.

[peteski]

You seem to have a serious paranoia about the household power being full of nasty spikes.  In my 6 decades of life I have never experienced damage to any electrical or electronic device which would have a footprint of being damaged by poor quality 120V AC.  Maybe different  parts of the country have issues with. It seems that power in the Northeast USA is fairly "clean".  At least in my experience.

Maybe you had some bad experiences with "dirty" AC power, so you just want to warn others about possible problems?