Hello,

I have got some problems with a couple of my 74490 turnout motors. They either won't work to any direction or only to one direction. Some manual switching helped temporarily, but now I think it is a good time to change all four main track turnout motors from 74490 to 74491 versions. I don't remember if many of my other 15 turnout motors are 74490 or 74491 versions... I hope that they are 74491 "improved" versions... I just read that these 74491 versions also fail similarly like older 74490 did = what a huge improvement mother Märklin has done .

So should I buy tomorrow four new 74491 and put my and praise the Lord that they will last forever or is it better to spray some CRC (what exact product?) to these 74490 that are having problems? Where should I spray that CRC to clean/lubricate the mechanism?

PS. I read somewhere that many people who have had problems with turnout motors have got them from starter sets. These are also from starter sets (29500 and 29680) and are wide angle turnouts 24711 and 24712. No problems so far with other turnouts (I cross my fingers...). I hope that I bought 74491's to other turnouts but I'm not sure which product there is.

Thanks in advance!

Best regards,
Janne

Hi Janne,

Have a look at my post regarding the repairing of the motors. Have a go at this and if it doesn't work, then buy the 74991's - if it works then you'll save some money to buy something else..
https://www.marklin-user...urnout-Motors-74990.aspx

Regards
Greg

Hello again,

I bought today four new 74491 turnout motors. Three of them works ok, but unfortunately one of these was already broken from factory. It had it's linkage loose and when I put it carefully back in place it won't work to it's other position... My dealer will give me a new 74491 and I return this to him. He sends it to Märklin.

So I had to take one of my still working 74490 and install it to this wide angle turnout. Now it works ok. Then I noticed that one other turnout had stopped working in other direction. So I had to take my last "spare part" working 74490 turnout motor and now all my turnouts work well. I hope that they will do it for a long time. I'm not in a hurry to install catenary or scenery, so I will just run my trains and use my turnouts to see if more of them will fail in the future. If after a year or so everything is still working then I will begin to install catenary and do the scenery work. My dealer told me that older 74490 version can be as reliable as "improved" 74491 version. All that is needed is good luck with these products really . Best option would be to have open space below every turnout. This is not possible in my layout.

Now when I have three failed 74490 I will try to fix them as I have nothing to loose. If I get them fixed I will use them later.

Regards,
Janne

Hi,
I'm sorry to tell you that I had that problem with 74490 after 2 and 3 years. (I don't have 74491, but it seems the problem is also there).
I would suggest you to short all the micro switches now.
Never read any report of electrical problems after that.
Can't understand why M continues to sell those *****!
Fred

Thanks from all replys,

If I short micro switches is it possible to see my turnouts position (straight or side track) from CS2? This is very important for me. I read that if micro switches are shorted it is not possible to see turnouts positions anymore.

I really hope that Märklin will make a 100 % working turnout motor version. It is too late to make a layout with openings below turnouts. It would be the best solution so far and worth doing if someone is building a new layout. As this is not possible for me anymore I will make sure that it will be always possible to lift tracks up without breaking out the scenery.

If these 74490/74491 break down even after 2-3 years use, then this just shows that these products are really unreliable. Are all really big layouts done so that these parts can be changed below? If not then it must be really frustrating when they have to be replaced.

It is odd that Märklin can't or don't want to fix this well known issue. People buy expensive CS2's, turnouts with digital decoders and turnout motors to control their expensive trains in their layouts. Then these relatively cheap turnout motors fail and some people have to tear their nice layouts apart to be able to change these 10-15 euro turnout motors... . If I could be 100 % sure that turnout motors would work forever I could pay more, say 20-30 euro for each one of them.

Best regards,

Janne

You are not alone!

I have endless problems with the motors. I have made holes under the turnouts, so that I can replace them from below.
If you short the switches, you can no longer read the position and I use the position to control signals and train-stops.
I consider to use servos instead in places where I am able to fit them in.

Jørgen

In fact, as the microswitches are SPDT, it's possible to use the 2d throw to check the turnout position. BUT that requires some dexterity (PCB to be lightly modified), and 2 more wires. I have not tested myself.
BTW, how can you see the real position of the points with the CS2? (I don't have a CS2).
There is also a special circuit that can do the job (from TAMS if I remember well).
So, nothing sraightforward, but it's worth having a look.
Fred

1)You'll be playing lottery with your time because if the microswitch has one of the contacts already damaged the opposite end has had the same amount of use. While it might work, it might not or it might fail soon after doing all the alterations Lets not even consider that you have fixed the scenery again. Is it worth your time?

2)I don't have the CS2 but it is probably the same as the Ecos. If the turnout is in the correct position the grphic appears normal. If it is not in the position it should be you'll get an X next to it. You also get the X while it is changing position, It is a very useful feature particularly for the turnouts that are out of sight.

Greg,

That was not a surprise for me that the "improved" 74491's will fail aswell... and it is very sad and frustrating when you have replaced so many of 74490's with these 74491's and installed them in ready scenery .

Tom and Fred,

CS2 can not see the real position of the turnouts. Only the position that turnouts should have. There is no feedback function. Thanks Tom about information. So I should be able to short the micro switches and after that the problems are gone? If it is like this I will do it to all of my turnouts. Then no more failing turnout motors, right? What exactly causes these failures then? Could someone give more precise information about these faults? My dealer told me that there is only this one thing that fails in turnout motors and otherwise they are very reliable.

Cheers,

Janne

Not at all.
Only one "pair" of contacts is damaged. No current ever flow in the other "pair" . I suggested to use that "new" pair. For the current needed for the feedback is low, no spark will damage it.
May be you could have a look at the cherry site to better understand how their microswitches are built.
Fred

Thanks Fred - didn't realise that!...so then its about even stevens methinks!!!...If the Viessmann is utterly reliable, I will change over...have had quite enough of the frustrations of having to regularly lift track and scenery...
thanks, Joe

hi Lasse - I use MS2, some with`decoders (74460), and some thru K83's...no diff, both troublesome...wondering if using control boxes 72720 would be "better"?
Joe

Maybe now is the time to bring the 60821 into the discussion. (2013NI for 4Q delivery)

While I still want to know exactly what it is and does and HOW it does it - the NewItems blurp makes reference to ...

- ... It is for using turnout mechanisms with motors with an end shut off feature ....
?? is this referring to the 74490/1/2 C-Track motor, the K-track motors ........ or something else ??
- .... you can program the set speed as well as a slow approach to the end position ....
?? WHAT ?? - does this mean removing the spring and forgoing the "click-clack" of the existing detention mechanism ??

- Is this signalling a newer or replacement turnout mechanism ? If so will they learn from past mistakes ?? or are they giving up on the onld design all together ??
- How can you justify an additional 16euros on top of the basic controlling hardware ? On face value an assumption might be made that a 60831 is just an updated 60830 (with DCC) but the fineprint implies you need another 4x60821 if you actually want to use the new box for (4) turnouts!

The WP2 is essentially a full wave rectifier, giving a DC pulse to switch the turnout. As mentioned earlier ( https://www.marklin-users.net/forum/yaf_postst14424_74490-turnout-motor-problem.aspx ) this works better in the long run. When using digital power, the turnouts see a pulsed digital current cut in half.

One of the problems for Märklin still is that the turnout motors have to be compatible with analog power, switching with regular AC directly out of a transformer and also with digital power, which is a completely different kind of switching power/current. When using analog, the power to the turnout motor remains on so long as you keep the switchboard button depressed. That is why these micro switches are needed. The WP2, in analog as well as digital switch mode, always produces a short DC pulse each time you switch the turnout, the pulse length dependent on the coil resistance.

The 74491 uses a varistor in an attempt to limit the voltage across the opening microswitch contacts thus suppressing sparks. We now indeed know that that is not really the solution either....

Regards, Robert

The WP2 is usefull when the point motor does not have end-switches, and when the control voltage is permanent, instead of pulsed. The WP2 is then necessary for not burning the coil. On the other hand, it gives a "DC" pulse, which is not as good (reliability point of view) as a time-limited AC signal, like the one delivered by a push button sending a AC (50 / 60 Hz) signal (also called 'analog" turnout switching). There are, in fact, less end-switches reliability problems reported on forums when using "analog" switching. (that does not mean NO problem).



No. When using a k83 for instance, the included 220uF capacitor filter, after the rectifier diode, is efficient enough for filtering the -roughly- 10 kHz digital signal, and the turnouts also see a "DC" pulse (let's rather call it a "monodirectional" pulse).


Could you give the characteristics of that varistor? Up to now, i read on forums that it was a capacitor (but, I think, nobody had made a real check)

Fred

Hi Fred,

Please take a look at the 74490/1 internals. You will find 2 single wound relay coils and an armature with a solid metal insert. Now please read a textbook on relays and you will find that this is typical DC relay architecture, not AC. Therefore it is better to use it on DC instead of AC, a short DC pulse is all that it needs.

On digital signal rectification: digital is a nominal 30V (+15 -15V) signal, pulsed with square/rectangular wave form. Put it thru a diode and only +15 or -15V remains. Put that (ripple is still 15V amplitude!) thru an elco and only some 8V or maybe less remains. Highly ineffective.

Regards, Robert

Hi Tom,

Putting a sinusoidal AC of, say, 12V through a bridge rectifier the theoretically resulting DC is 20,8V (i.e without losses through the diode PN boundaries). Sinusoidal 12V AC is the effective voltage or RMS value. The voltage amplitude therefore is 20,8V or +10,4 -10,4V. A digital voltage where the wave form is rectangular cannot be treated this way, the voltage is often expressed as amplitude or peak voltage, i.e. the max. between the low and the high peaks are used to give the voltage value. But not always.

Now, using a regular multimeter to reliably measure digital voltages is therefore not possible, in DC mode the reading will vary, sometimes strongly, depending on the frequency and wave form in relation to the sampling rate of the multimeter whereas in AC mode it will return a "fictitious" RMS value based on the false assumption that it is measuring a sinusoidal AC voltage.

Frankly, I don't know what type of value the CS2 displays, be it peak voltage, "fictitious" RMS or some other value. In the digital world the only consensus is to lay down what the voltage measurement method is to make sure we and others know what we are taking about. At least so long as that is of any importance. Stated otherwise: there are several conventions for the measurement and publication of digital voltage values and unless the convention used is indicated, values cannot be compared.

Now, putting such a digital signal through a single diode rectifier which is what happens in MM turnout decoders, the peak to peak voltage is cut in half. No matter whether that voltage is expressed as 30V or +15 -15V. Or +11 -11V for a 22V amplitude, etc. A smoothing capacitor is normally used in any Graetz circuit to smooth out the ripple that comes out of the full bridge rectifier. Using a capacitor to smooth out the + or - 15V (or 11V) "ripple" after single diode rectification of the digital voltage, the loss will depend on the resulting waveform after the diode, i.e. whether the high part is longer or shorter than the low (0V) part of the signal, independent of frequency. But it will be quite considerable.

As for H bridges, they don't enter into the equation. The turnout decoder or better its output diode sees a peak to peak voltage and simply cuts it in half as every self-respecting diode should.

Regards, Robert

Regards, Robert

Hi Tom,

I dearly wished you were right but capacitors don't rise voltages. If they really do please tell RWE, Eon and all the others, Merkel included, immediately, power prices could drop and I can finally afford running crocodile consists on my layout!

Regards, Robert

Power is NOT equal to voltage.

Explain please.

motors not working properly:
I've found

a.) the circuit board was faulty
b.) the micro switch no longer made contact. (when installing these micro switches at the factory, they sometimes didn't align the switches properly and secondly by soldering them onto the circuit board if you apply too much heat the switch loses its functionality, the same switches are used for the c-track switching tracks and found the same problem whereas the lever doesn't go back to its neutral position. on both items I've exchanged the switch and repaired the circuit board

John

Even my HiFi has an RMS output wattage - and what you hear is neither AC nor DC.
RMS voltage can be calculated for any wave form. Good true RMS meters handle frequencies of 100 kHz and more. This is needed to get the effective voltage of DC with a ripple voltage.
Pass 16 V AC through a bridge rectifier and the effective voltage is still 16 V (still neglecting the loss) and not 22.6 V. The peak voltage is 22.6 V (100 or 120 times a second), but voltage will also be 0 V (100 or 120 times a second), thus the effective voltage has to be lower than the peak voltage because the current is not flowing all the time.
Rectifiers normally don't pass the voltage through a "cap" (you cannot pass DC through a capacitor, it allows only AC to pass), they charge a capacitor to reduce the ripple and increase the effective voltage.

No need to mention the obvious ...
At this point I'll stop discussing the electronics 101 as it is somewhat off topic.


Basic electric principles is something that should be explained if it can help the understanding of how things work.
For RMS, it is dependent on the waveform of pulses... The digital signals on the track are not truly measurable since
the square wave signal vary the pulse length and polarity. The MM protocol is a bit biased towards negative polarity
for longer pulses so true RMS is virtually impossible to measure correctly. /Webmaster
For RMS with fixed symmetrical waveforms -> https://en.wikipedia.org/wiki/Root_mean_square

Edited by moderator 22 June 2013 23:25:55(UTC)  | Reason: Not specified

Hello,

I have now shorted all my turnout motor micro switches. There is 18 of them in use at my layout's 17 turnouts (one is a three way turnout that has two of them). I also did the same micro switch short thing for my four spare turnout motors. So I did this also to my new 74491 ones and I don't have to return the "broken" one to my dealer. Every one of these 22 turnout motors works now!

While I was soldering these I noticed some interesting things. There is turnout motor versions and sometimes also production date/year on a sticker (clear one or white one) outside of turnout motor. Older ones don't have any sticker and version or manufacturing date info outside. Inside there is always turnout motor version and manufacturing month/year of the electronics. All my V1.4 are made 04/2010. I have only two older version V1.2 turnout motors (74490) from 1999. Then some of my turnout motors are version V1.3 from year 2006 (also 74490). Most of them are newest version V1.4 and from years 2010-2013 (including both 74490 and 74491 which are 100% same inside in version V1.4!!! ).

So Märklin has changed already the turnout motors inside to the newest V1.4 version before they re-numbered their product to 74491 from 74490! Version V1.3 has not that small electric component? between micro switch terminals and all version V1.4 turnout motors 74490 and 74491 has it. I took carefully that electric component away with my soldering iron and after that shorted the terminals. Actually this micro switch terminal shorting is easier with versions V1.2 and V1.3 as it is only required to short the micro switch terminals with soldering. As these older versions has three terminal micro switches it is easy to solder two shorter "solderings" between the terminals. When shorting these newer V1.4 micro switch terminals first it is needed to take away carefully that very small electric component between the terminals. Give some heat with the soldering iron to both sides, but not too much as otherwise those micro switches can get loose and move accidentally. When that small component is removed succesfully then a longer "soldering" is needed between the two micro switch terminals as this newer version V1.4 has only two terminals.

I was very surprised to see that also the newer 74490 has the same V1.4 version, which is identic inside that the "new and improved" 74491... I'm glad that all of them are now fixed and I will inform immediately to this forum if some of these fixed (shorted) ones will still fail. I really hope that now they will work for many, many reliable years .

I recommend to everybody to do this fix (short the micro switch terminals) if you use the turnout motors at digital layout with CS or MS controller (not with any control boxes). You have to be careful and have basic soldering skills. That YouTube video shows what should be done, but it is for the older versions. For version V1.4 see above. There is no real benefit to upgrade them to 74491 version (I think) as they look 100% identic inside as 74490 version V1.4 that has been in sale for years.

Cheers,

Janne

Thanks Janne! You were brave to even "fix" the new ones!!
John VR very kindly took 2 of my "only working one way" 74991's and did the shorting out of the switches - and hey presto, they are both working now - both ways, all the time...so now, (don't tell John), but I have another 8 or so of 74490/74491's, and even a box of five new 74491's for him to do!!
Thanks John...:) see U this weekend?!?
Joe

Hi all!

Well, I had huge problems with my turnout motors 74490. Some I have replaced by the newer version, to find that after a while they basically do the same thing, and started to fail. My solution to the problem was to soak (yes you read right) them with contact cleaner (from Philips), let them rest for a while and after that I have used an air compressor to remove the excess of the contact cleaner. To this day they have not failed anymore, massive improvement.

Regards!

Miguel