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Offline Donb  
#1 Posted : 06 March 2020 23:14:54(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
Hi,

I have this old 26506 set that I enjoy running once in a while.
This time, I noticed a clicking sound coming from the coaches when parked, and my Marklin signals were flickering with the clicks.
So I dissassembled one of the baggage cars (with pickup) and one of the coaches, and found that there is a rather large Electrolytic capacitor on the circuit board, connected to ground. Thinking that this might be for interfernce suppression, I removed them and now the lights continue to operate normally and the clicking is gone. The signals no longer flicker.
Thought I'd ask the experts here about this before I dissassemble all the coaches and remove the capacitors.
Am I on the right path here?

Rheingold coach curcuit.jpgRheingold coach.jpg
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
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Offline thing fish  
#2 Posted : 07 March 2020 08:44:39(UTC)
thing fish

Turkey   
Joined: 25/01/2020(UTC)
Posts: 143
Location: istanbul
I'm writing only to be notified as I'm very much interested in the opinions; I have the same set.

C.
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Offline JohnjeanB  
#3 Posted : 07 March 2020 12:32:15(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 893
Location: Paris, France
Hi
I have the Rheingold set of cars w/o the loco you have.
I never opened it because I had no problem.
On a typical Märklin car with interior lighting you will find a PCB with a dual wave rectifier, a large capacitor (to avoid flickering) , LEDs arrange in series / parallel with resistors and I believe no noise suppressor capacitor.
So my guess: your capacitor went bad, you removed it, light still work but you probably need to replace the capacitor with another one (minimum 25 V and 100 microFarad)
I hope this helps

Jean
My lay-out videos
latest vid
humping yard
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Offline Donb  
#4 Posted : 07 March 2020 16:41:53(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
Thanks Jean,

I have ordered replacement capacitors from Digi-Key, originals are 10uF, 100V in the baggage car and 10uF 50v PC mount in coaches.
I'll report back here once I have them installed.

Don
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
Offline Donb  
#5 Posted : 07 March 2020 19:21:45(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
Some further interesting test results,
I had a hunch that the regular ( every 1.5 secs) clicking was from the Mfx track signal, so I hooked up my old MS2 to a test track and set the protocol to MM and placed a baggage car with old capacitor in it, no clicking. If I set the protocol to Mfx, clicking resumed. So it appears MM or DCC protocol no clicking.

I dont know why I never noticed this clicking before, likely as when the train is running there is so much rolling noise you cant hear it. Never noticed the signals flickering either, so thats a puzzle.
So it appears the only way for me to eliminate the clicking with Mfx for my set is to remove the capacitors.
Or.... I switch back to using my Intellibox :)

I'll still install a new capacitor and check this again, but I dont think that will make any difference.

If you that have the same set and are using Mfx track signal and do not experience this clicking, then that would suggest I have a different problem with these cars. You have to put your ear right down to the coach ( coach stationary) to hear it.

Don
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
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Offline Hannes Porsche  
#6 Posted : 07 March 2020 23:36:30(UTC)
Hannes Porsche

South Africa   
Joined: 08/12/2015(UTC)
Posts: 35
Location: Western Cape, South Africa
Hallo Don,
Interesting observations you put forward on this tweet.

Firstly I see dark discoloring on the PCB right next to the four pinned rectifier. I hope that was not due to components overheating.
The electrolytic capacitor negative must be connected to the negative of the rectifier, and not ground.
That whole PCB has no relays that can produce mechanical noises, so use a stethoscope/pipe to locate the origin of the noise.
Then I suspect that the capacitor is arcing internally. Building up voltage and then periodically discharging through a short.
Finally the capacitor will react similarly to MM, Delta, ........etc protocol should not be of any consequence.

Good luck,

HANNES.BigGrin
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Offline Donb  
#7 Posted : 08 March 2020 00:58:51(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
Originally Posted by: Hannes Porsche Go to Quoted Post
Hallo Don,
Interesting observations you put forward on this tweet.

Firstly I see dark discoloring on the PCB right next to the four pinned rectifier. I hope that was not due to components overheating.
The electrolytic capacitor negative must be connected to the negative of the rectifier, and not ground.
That whole PCB has no relays that can produce mechanical noises, so use a stethoscope/pipe to locate the origin of the noise.
Then I suspect that the capacitor is arcing internally. Building up voltage and then periodically discharging through a short.
Finally the capacitor will react similarly to MM, Delta, ........etc protocol should not be of any consequence.

Good luck,

HANNES.BigGrin


Hi Hannes,

The dark part you are referring to is actually the power clip for connecting the wire from the slider.
There are two, three pin rectifiers further along the circuit board, beyond the capacitor.
There are no signs of overheating on any of the components.
But you have me thinking that maybe the rectifiers are failing.

Thanks for the point about the capacitor polarity, but Maerklin make it easy as they have printed the correct polarity on the PCB, so that old guys like me cant mess it up. As you say, the negative is connected to the rectifier, positive to ground.

I'll have the new capacitors tomorrow,

Cheers,

Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
Offline Donb  
#8 Posted : 09 March 2020 16:56:43(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
So the new capacitors did not solve the issue.

For some reason removing the capacitors solves the issue, but will perhaps create another.
Again, this issue only occurs if Mfx protocol is active on the rails.
Unfortunately, Maerklin has discontinued the availibility of new circuit boards. Those rectifier chips are too small to replace, at least by me.

I have set this aside to do some more head scratching.
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
Offline tiono  
#9 Posted : 12 March 2020 17:23:59(UTC)
tiono

United States   
Joined: 09/02/2010(UTC)
Posts: 234
Originally Posted by: Donb Go to Quoted Post
So the new capacitors did not solve the issue.

For some reason removing the capacitors solves the issue, but will perhaps create another.
Again, this issue only occurs if Mfx protocol is active on the rails.
Unfortunately, Maerklin has discontinued the availibility of new circuit boards. Those rectifier chips are too small to replace, at least by me.

I have set this aside to do some more head scratching.


Did the clicking always happen at certain location, or can be anywhere on the lay out?
During the clicking (and the signal flicker), did all other devices which drawing power from the same track also flicker?

A capacitor will initially draw high current (in very short period of time depending its value). Some section of track may have bad electrical contact which become intermittent when the capacitor pull high current, causing flicker. The problem was solved by removing the capacitor, but this is not the solution because the actual problem is somewhere else instead of the capacitor.


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Offline Donb  
#10 Posted : 13 March 2020 15:31:44(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
Originally Posted by: tiono Go to Quoted Post
Originally Posted by: Donb Go to Quoted Post
So the new capacitors did not solve the issue.

For some reason removing the capacitors solves the issue, but will perhaps create another.
Again, this issue only occurs if Mfx protocol is active on the rails.
Unfortunately, Maerklin has discontinued the availibility of new circuit boards. Those rectifier chips are too small to replace, at least by me.

I have set this aside to do some more head scratching.


Did the clicking always happen at certain location, or can be anywhere on the lay out?
During the clicking (and the signal flicker), did all other devices which drawing power from the same track also flicker?

A capacitor will initially draw high current (in very short period of time depending its value). Some section of track may have bad electrical contact which become intermittent when the capacitor pull high current, causing flicker. The problem was solved by removing the capacitor, but this is not the solution because the actual problem is somewhere else instead of the capacitor.




Hi,

The clicking occurs anywhere on the layout. other devices on the track function normally. I have two signals connected to track power, one is the Marklin signal which flickers in sync with the clicking, the other is a Viessmann signal, it does not flicker.
This only happens when the 26506 coach set in on the tracks, none of my other coach sets (illuminated) do this.
I am thinking that the rectifiers are failing.

Don
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
Offline Donb  
#11 Posted : 15 March 2020 21:23:23(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
Hi,

I have identified the SMD's and they are:
The upper one in the photo is T1p (Transistor) BCX17, SOT23 package, 45v, 0.5A.
The lower one in the photo is Z12 (Zener Diode) BZX84-C2V7,SOT 23 package, 2.7v, .3w

I have a voltmeter with a Diode Check setting, is there a way to test the Diode, and maybe the transistor, while it is still on the board?

Thanks,

Don

26506 rectifier.jpg
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
Offline tiono  
#12 Posted : 16 March 2020 14:00:39(UTC)
tiono

United States   
Joined: 09/02/2010(UTC)
Posts: 234
Originally Posted by: Donb Go to Quoted Post

I have a voltmeter with a Diode Check setting, is there a way to test the Diode, and maybe the transistor, while it is still on the board?


The zener diode, and rectifier diode can be tested on board, however, the transistor may not.
Below is the schematic diagram of Marklin 4228 (Class 1 coach). Class 2 coach will have different resistor value, and more LEDs (thus, different current setting) but the circuit is still the same.
It is a current regulator circuit, which provide around 15 mA.

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Offline Donb  
#13 Posted : 17 March 2020 01:28:26(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
My measurements with the voltmeter in Diode check mode are:

Rectifier Diode: Fwd bias .586v, Rev bias 0 v so this seems ok.

Zener Diode: Fwd bias .675v, Rev Bias .805v
I think zener diodes can pass current in both directions if a certain voltage is applied, not sure if this is a good result or not.

The LED's all check out ok, fwd 1.717v, rev 0
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
Offline tiono  
#14 Posted : 17 March 2020 03:25:19(UTC)
tiono

United States   
Joined: 09/02/2010(UTC)
Posts: 234
Zener diode behave similar as rectifier diode if the applied voltage is less than its break-down voltage.
Probably you should connect the circuit to track, then measure the voltage across R2 (resistor between transistor and zener), which should be around 2V to 2.5V if the zener is 2.7V


Originally Posted by: Donb Go to Quoted Post
My measurements with the voltmeter in Diode check mode are:

Rectifier Diode: Fwd bias .586v, Rev bias 0 v so this seems ok.

Zener Diode: Fwd bias .675v, Rev Bias .805v
I think zener diodes can pass current in both directions if a certain voltage is applied, not sure if this is a good result or not.

The LED's all check out ok, fwd 1.717v, rev 0


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Offline Donb  
#15 Posted : 17 March 2020 20:51:36(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
Originally Posted by: tiono Go to Quoted Post
Zener diode behave similar as rectifier diode if the applied voltage is less than its break-down voltage.
Probably you should connect the circuit to track, then measure the voltage across R2 (resistor between transistor and zener), which should be around 2V to 2.5V if the zener is 2.7V


Originally Posted by: Donb Go to Quoted Post
My measurements with the voltmeter in Diode check mode are:

Rectifier Diode: Fwd bias .586v, Rev bias 0 v so this seems ok.

Zener Diode: Fwd bias .675v, Rev Bias .805v
I think zener diodes can pass current in both directions if a certain voltage is applied, not sure if this is a good result or not.

The LED's all check out ok, fwd 1.717v, rev 0




The voltage across R2 is 2.20v in baggage car, and 2.14v in 2nd class coach.

However, I noticed that when I had the curcuit board out of the chassis and connected to track power via alligator clips, no clicking, even with Mfx. When I replaced the curcuit board into the chassis, the clicking resumed. Interesting.
So I dissembled the bogies completely and cleaned with rubbing alchohol and polished the ends of the axles. Continuity check was good, but I cleaned anyway. However, still clicking.
The chassis are plastic so no shorting possible. The current conducting coupling assemblies look normal.
The chassis is very simple, so this has me quite puzzled.
The clicking only occurs with Mfx active.

Stay healthy and safe!
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
Offline tiono  
#16 Posted : 18 March 2020 03:21:28(UTC)
tiono

United States   
Joined: 09/02/2010(UTC)
Posts: 234
Originally Posted by: Donb Go to Quoted Post

However, I noticed that when I had the curcuit board out of the chassis and connected to track power via alligator clips, no clicking, even with Mfx. When I replaced the curcuit board into the chassis, the clicking resumed. Interesting.


Seems as there is intermittent contact somewhere. Probably loose contact between the circuit board and ground clip (springy brass above the bogie) ? or the current conducting coupler?
But from what you have described, I guess the problem is mechanical rather than electronic component. It will be more difficult to find if the problem is pcb path (sometimes the pcb is corroded, and there is a hairline crack at the conducting path).
When you connected using alligator clips, did you clip it on the board exactly at the ground contact above the bogie, and the other alligator clip on the contact of conducting coupler?
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Offline Donb  
#17 Posted : 18 March 2020 04:48:10(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
Originally Posted by: tiono Go to Quoted Post
Originally Posted by: Donb Go to Quoted Post

However, I noticed that when I had the curcuit board out of the chassis and connected to track power via alligator clips, no clicking, even with Mfx. When I replaced the curcuit board into the chassis, the clicking resumed. Interesting.


Seems as there is intermittent contact somewhere. Probably loose contact between the circuit board and ground clip (springy brass above the bogie) ? or the current conducting coupler?
But from what you have described, I guess the problem is mechanical rather than electronic component. It will be more difficult to find if the problem is pcb path (sometimes the pcb is corroded, and there is a hairline crack at the conducting path).
When you connected using alligator clips, did you clip it on the board exactly at the ground contact above the bogie, and the other alligator clip on the contact of conducting coupler?


Hi Tiono,

Yes, clips were positioned per photo.
I bent the ground clip and coupler contact springs upwards slightly to increase contact pressure with the circuit board, didn't help.

There is probably something simple I am missing....Confused

26506 board connect.jpg26506 chassis.jpg
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
Offline tiono  
#18 Posted : 18 March 2020 06:34:55(UTC)
tiono

United States   
Joined: 09/02/2010(UTC)
Posts: 234
may be try this way:
Put the board back into the chassis, but without the metal coach body. Just the plastic chassis + bogie + board. (you can put the interior seat back, should not be any difference since it is plastic)
Check whether the problem is still happening.
- if the problem disappear: probably the metal body intermittenly in contact with the board or other electrical line.
- if the problem is still there: try connecting the center rail to the protruding metal stud below the chassis using alligator clip (this metal stud is the one soldered at the board, next to capacitor). Then test again. If problem disappear, then the suspect would be the conducting-coupler mechanism.
if the problem persist: try connecting the outer rail to the wheel or the center pin below the bogie, using alligator clip or a cable. If problem disappear: the suspect is bad contact of the bogie-wheel-center pin and rail.
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Offline Donb  
#19 Posted : 19 March 2020 18:21:44(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 141
Location: Fraser Valley
Using this process of elimination, working back from the circuit board, I have found that the audible clicking begins when the rail alligator clip is attached to the bogie sidebars. The red wire can be connected to the coupling or center pin, no difference.

So I disassembled the sidebars, polished and cleaned the mating surfaces and applied some dielectric grease. No improvement.
I then applied more weight to the coach chassis, still clicking.
Then I attached alligator clips to clamp the side bars to the bogie pivot plate. Still clicking.
Then I applied dielectric grease to the axles/side plate holes, no change.

As a next step, I think I'll disassemble the bogie (yet again) and apply dialectric grease to the bogie pivot plate/ground pin interface.
Other than that Ive run out of ideas.
Best Regards,
Don
___________________________________________________________________________________
Commander , Intellibox 2, MS2, C track
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