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I think I just found something.  The other day, when I was testing this for the umpteenth time, I hooked two multimeters to it so I could measure ACCESS PWR out (which should measure the same as the voltage in and did), as well as clipping the other meter to the NO out. I thought I was getting a voltage pulse when triggering the sensor, but couldn't get it to repeat it. I just did the same thing and figured out (I think) why the sensor is working but not triggering the NO switch (or at least what it controls). I got a voltage pulse, but it was less than 4V.   I'm sure that's not enough to trigger the solenoid in a Gateman. one of the other IC chips bad and not sending enough voltage out the NO line (or for that matter NC as the voltage there was the same)?

Based on diagrams in the Lionel instructions and confirmed by inspecting your the photos of the boards, the 153IR uses the relay to steer ACC GND to either the NC terminal (when relay is not triggered) or to the NO terminal (when the relay is triggered/clicked).  In other words if the relay is working, ACC GND is connected to either NC or NO.

So.  Apparently you are powering the 153IR with 14V AC Accessory Voltage.  A meter should measure AC voltage as follows:

Untriggered: 14V AC between ACC PWR and NC, 0V AC between ACC PWR and NO

Triggered (relay clicked): 0V AC between ACC PWR and NC, 14V AC between ACC PWR and NO

Due to leakage and measurement artifacts, 0V may register as some small voltage. 

So if I understand, with the unit dis-assembled but powered up to operate:


When untriggered, you measure 0V between ACC PWR and NO, 4V AC between ACC PWR and NC.

When triggered, you measure 4V AC between ACC PWR and NO, 0V AC between ACC PWR and NC.

And you previously measred 0 Ohms (or 0.3 Ohms) between NC and ACC GND (when unit unpowered).

Is there 14V AC between ACC PWR and ACC GND?


Images (1)
  • IMG_0043

Almost there.  So the situation is as follows.  In the untriggered state you are measuring 14V between A-B...but only 4V between A-F.  Where did the 10V go?!  

find the drop untriggered

So if I still have your interest, can you use your meter and measure the voltage starting at A-B (which you say is 14V and always has been)...and move the meter lead from point B to point C, then to point D, etc., until point F (where it drops to 4V).  Note the blue lines above indicate the connections on the board that you cannot see on the board traces.  That is you have the 15mm wire-jumper you repaired.  And the untriggered relay makes the connection between points D and E.   In other words A-B is 14V, A-C is ?V, A-D is ?V, A-E is ?V, A-F is 4V.

I think this will locate the vanishing 10V.

If it is convenient to put some object in front of the sensor to trigger/click the relay, you can hunt for the mysterious voltage drop in the triggered state as follows:

find the drop triggered

You still have the 15mm jumper, but when triggered the relay makes the blue connection between D and G (rather than D and E when untriggered).  So the measurements are A-B is 14V, A-C is ?V, A-D is ?V, A-G is ?V, A-H is 4V.


Images (2)
  • find the drop untriggered
  • find the drop triggered
Last edited by stan2004

Oh, you definitely have my interest, Stan. Don't worry about that.   I'll have some time later this afternoon to do those measurements, so I'll be back then.    But a couple of clarifications.        I'm using variable voltage IN (from my 1033 test trans.) it's not fixed 14V (not that it matters, I'm thinking).  Also.....that 4V pulse appears between B and F and B and H when I trigger the sensor. 

Understood.  And that's why I wanted to be absolutely clear on what points to measure.  In any event I figured you can leave one meter lead on the A terminal...and just move the other meter lead from B, C, D, E, etc..

Also want to confirm when you say "pulse" that whatever voltage reading is present for as long as the relay is triggered.  This is just to be clear that you are not using "pulse" to describe a transient voltage (like for 1 second or whatever) that appears only momentarily when the relay first triggers but quickly vanishes even though the relay is clicked on (until it times out many seconds later).


According to my readings.......this thing should be working (or at least I think).Here are the first set of measurements.....untriggered

A/B: 10.83V

B/C: 10.83

B/D: 10.81

B/E:   1.37

B/F:   1. 41

Second set.....Triggered

A/B: 10.82V

B/C: 10.82

B/D: 10.83

B/E: 10.83

B/F: 10.83

I went back and did the untriggered readings again and got the same.  Triggered,I'm getting 10.83 at E and F       ?????????

Is it possible, that when I reassemble, the harnesses come loose?   This looks like it should work


Something weird is going on here, Stan.   After I sent out the results, I realized I did all of my tests from the B terminal and not A.  And it seemed like it was working properly.   When I reread your directions, I realized I should be using the A terminal.

Here's what I got......untriggered

A/B:  10.83

A/C: 0

A/D: 0

A/E: 1.17

A/F: 1.15


A/B: 10.83

A/C:    .447

A/D:   0

A/E: 1.05

A/F: 4.2

Is it possible that the A and B terminals got reversed somehow?

Are you making the ALL the measurements with one meter lead on the "A" terminal (ACC PWR)?   It looks to me that most of your measurements have "B" terminal (ACC GND) as one of the meter lead points.

As discussed earlier the 153IR essentially "outputs" 0V (to either NO or NC depending on untriggered or triggered).  You have to kind of think backwards and also measure the outputs backwards.  It's kind of like how insulated-rail triggering works...when a wheel truck enters the insulated-rail track section it applies the outer rail or "GND" voltage to the controlled accessory (gateman, crossing gate, whatever).

Last edited by stan2004

OK. This may not be the only problem, but I think your 15mm jumper wire is not doing its job.

15mm jumper questionable

The hastily scribbled area in above photo should all be at the same voltage.  So B, C, and D should be at the same voltage because they are physically connected together by either the circuit board trace or the 15mm jumper.  Hence, A-B, A-C, and A-D should all measure the same.  That this "chain" is broken between B and C (that is your measurement of A-B and A-C goes south), suggests there is a break in your jumper.  It could be a "cold" solder joint where the solder is not shiny silver but a dull gray and hence not making a solid connection.  For example, take a hot iron and "touch up" the various solder joints and then re-measure.  Again, A-B and A-C, and A-D must measure the same (for both the triggered and untriggered scenario) ifs, ands, or buts!


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  • 15mm jumper questionable
Last edited by stan2004

You may have more than 1 problem. 

As before you absolutely must get to the bottom of why the measurement of A-B and A-C differ.  B and C are the same voltage.  Note that on your board the drop occurs irrespective of whether the relay is triggered or untriggered.  So for the matter at hand I'm treating it as independent of any relay issues and must be resolved.  In looking at the board, I'd say you have a problem in the yellow circled "node" where 4 connections join - 1) BLK ACC GND wire, 2) right side of 15mm jumper wire, 3) one leg of the bridge rectifier, 4) external terminal for ACC GND:

suspect node

When you "touched up" the 15mm jumper, was this on the back (as shown above) of the board?  I'm claiming the 15mm jumper is not making a solid/reliable connection to the circled node.

Very carefully inspect that yellow circled node.  I think you have an intermittent or loose connection.  It may be a bad solder joint, a tiny hairline crack in a circuit board trace, whatever.  You may not have enough hands to do this, but, for example you could use a toothpick to apply pressure to various points in and around the yellow circle to see if the A-C voltage jumps up the value of the A-B voltage.  In other words simply flexing the board or putting the slightest mechanical pressure on a solder joint may re-establish connection.

As noted above, this node also connects to the bridge rectifier.  So if there is a flakey connection, this might explain why the relay is intermittent.  That is, if the bridge rectifier is not receiving ACC GND, the sensor board cannot generate 5V and hence cannot click the relay. 

But solve the "why is A-B different than A-C" problem first - possibly by re-heating that entire blob of solder in the circled area if your iron is strong enough.

I cannot explain the mysterious reversal of NO and NC behavior...but I say you need to solve the above problem first.


Images (1)
  • suspect node
Last edited by stan2004


Today I seem to be getting consistent readings for A/B, A/C, A/D.  All the same.   But, as with last night's readings, I get full voltage from A/NO (which doesn't seem to change when triggered). And 1.37V from A/NC (which also doesn't seem to change).  When I trigger the relay, it does ALOT of chattering.....buzzing, actually.   But the thing is......those voltage readings seem the opposite for NO and NC seem opposite of what they should be...let alone that they don't change.  It also seems to me, that if I'm getting full voltage out of NO, how come when I connect this to the Gateman, it doesn't activate the solenoid? 

As for the "blob".   Looks like a blob in the photo (reflections). But the solder points are quite distinct. In any case, I heated them all and it's all shiny. No different. As for how I "repaired" the jumper, it was all above the board. I get good continuity between all the solder points in the trace from the "blob". 

And the mystery continues.......

This is arcade Whack-a-mole.  So the voltage drop is gone but up pops the buzzing relay.  That typically means the relay coil is being driven by some choppy 60 Hz voltage rather than a steady/solid 5V DC - probably an issue with the DC power supply circuit.

The scenario where it appears you have suitable voltage (measured with a meter) to drive a solenoid but then there's no action when you actually attach the solenoid load suggests some kind of resistance or poor electrical connection in the path.

I'm hearing the Kenny Rogers tune "The Gambler":

You've got to know when to hold 'em, know when to fold 'em,. Know when to walk away, know when to run.



What are you going to do with it?  If it's just going to be a paper weight can we work out a way to get it to me?  I have more sophisticated electronic tools that could probably get to the bottom of it.  I am not soliciting any paid services.  In any event I'd return the unit to you...dead or alive.  So we're only talking about shipping costs. 

Morbid curiosity is one way of describing my interest! 

stan2004 posted:
You've got to know when to hold 'em, know when to fold 'em,. Know when to walk away, know when to run.

Stan, the only thing that amazes me is I don't think you have a good grasp on know when to run!

I didn't comment because I couldn't think of anything to add to what you were doing.  Don't leave us hanging, I've been following along, I confess I'm curious what the issue really is.

Last edited by gunrunnerjohn
gunrunnerjohn posted:
stan2004 posted:
You've got to know when to hold 'em, know when to fold 'em,. Know when to walk away, know when to run.

Stan, the only thing that amazes me is I don't think you have a good grasp on know when to run!

I didn't comment because I couldn't think of anything to add to what you were doing.  Don't leave us hanging, I've been following along, I confess I'm curious what the issue really is.

OK.  I'll post the autopsy results if that's an appropriate term for an inert circuit board!

As for knowing when to run, doesn't it come down to which direction you run?  Towards or away from the the sound of gunfire.  As a gun runner, I'm sure you can appreciate this!   

Hey Guys,

Very interesting, I had the original thread IR controller that Stan reference earlier.  I still haven't taken time to play with the Oscilloscope and follow Stan's instructions.  Many other activities keep me busy.  I have never put the guts back in the box.  The box is now scenery on the layout.  Someday...

stan2004 posted:

Email sent.  It seems this thread has devolved into a conversation just between you and me.  I will report my findings to you!

Hey, I'm still here too, lurking in the shadows and following along to see the final outcome.

Stan, please post your findings to this thread as I am still interested. Even though I am probably lost about half the time, these are my favorite type of threads!! 

If my knee holds out, I will be just in front of GRJ when I hear the gunfire, if not I will be just behind him. Running away of course. 

Last edited by rtr12

The problem is with the microcontroller (uC) chip which is custom/programmed so sadly it's game-over.

153IR teardown

But I was interested in how it works so here are some "tear down" notes...

The AC power (it actually will operate on DC too) goes through a bridge rectifier, hops over the 6-pin cables, and is regulated to 5V DC by the 34063A switchmode/buck regulator IC.  A diode drops this to about 4.75V DC and this powers the uC chip; so the 5V testpoint on the board actually measures this lower uC voltage which is a little confusing when troubleshooting this module for the first time.  The "full" 5V is used for other parts of the circuit as well as being wired back to the power board over the 6-pin harness.

The IR LED emitter is indeed pulsing.  The LM567C PLL chip is configured as a 10 kHz oscillator/phase detector.  It's 10 kHz output pulses the IR LED via a NPN transistor with current limited by the "Sensitivity" control knob/potentiometer.  Maximum or highest sensitivity means max current driving the LED hardest. The purple glow is indeed there - though best/easiest to see when set to maximum sensitivity; here's what it looks like ON and OFF as viewed thru a digital camera.

153ir emitter glow - high sensitivity

When an object is in the sensor range, it reflects the pulsing IR energy.  The IR detector signal is amplified by a 741C op-amp and feeds back to the PLL.  The PLL "knows" the frequency to look for since it created it and generates a "triggered" signal when it sees a reflected signal at the magic frequency.

The "triggered" signal from the PLL feeds the uC which activates the relay with a time-delay set by the "time" adjustment knob/potentiometer.  Best I can tell, this time-delay is the sole function of the custom uC chip.  As noted earlier, the markings are sanded off the chip.


As to the specific of Roger's boards.  Firstly, it sure was a good thing we folded the cards before upping the pot with a few more rounds!

1. The relay buzzing was from intermittent 5V due to intermittent solder connection on the replaced 5V voltage regulator.

2. The apparent backwards NO/NC behavior was due to the defective uC chip.  In fact, when first turned on, the relay actually triggers even if nothing is present.  Put hand in front of sensor and the relay turns OFF.  Take hand away and relay turns ON.  So the uC chip was driving the relay backwards.  So while I suppose one could develop the skill to hear the difference between a relay "click" going off-to-on vs. on-to-off, that's would be above my pay grade.  Anyway, that's my guess as to the backwards behavior.

3. After maybe half a minute of operation, the relay simply stays ON.  I can see the PLL detector operating properly sensing presence/absence and sending a high and low signal to the uC.  But the uC relay drive output is stuck ON.  Then, spray some component-cooler on the uC chip and it starts operating backwards.  Wait a bit as the chip warms up and back to stuck ON.  The uC chip is done.

4. Under no circumstance could I get the "time" control to change the delay of the relay.  Of course the "time" control is an analog voltage feeding the uC so, again, the uC is mis-behaving.

So there you have!


Images (2)
  • 153IR teardown
  • 153ir emitter glow - high sensitivity

Yes, Thanks Stan!

That was a very informative description of trouble shooting, operation and problems found. I learn a little more with each one of these threads and I really do enjoy following along, even though I don't comment a lot (and I get lost occasionally). With more threads like this and a little luck, I might even make it to the 'knowing just enough to be dangerous' stage someday.  

Interesting thread, and I’m learning a lot...

I’m wiring one of my 153IR controllers to a 14098 crossing gate(s). What I need to know is why does the manual specify “do not use a wire larger than 24 gauge!” That means 28 gauge is okay, but not 20 gauge? Why would larger wire (say 20 gauge), with its lower resistance, cause a problem? Do they mean literally don’t use a ‘gauge number’ larger than 24? 

and do you think it’s safe to hook up both of the 14098 gates to a single 153IR? Or could that somehow fry the controller?

I've used the 153IR on my last layout and this new one..

I only use the 153IR as a trigger to activate a automobile relay 12V DC I use a bridge rectifier to activate the switch part and  use my Lionel voltage  to go to the other pin which then goes to my accessories   (i have many accessories running off of one relay  and never a problem with the 153IR because its only activating the relay (only) hope this helps  daniel

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