Relay spring tension inconsistent/too heavy?

Oxidised/dirty contacts at the back end of the reverser where the moving arm pushes?

Moving arm (that switch left/right pusher) not moving freely enough?

Too much/little pressure in the spring that pushes that moving rocker thingy upwards - the piece pushed by the "moving arm" that switches the the contact poles?

Just my immediate layman thoughts... Electrical coil faults are not so common...

Thanks Juhan,

At first I also thought the problem could be from the reverse unit spring, after I realised that even if the spring was not OK, it could not be the main cause. All other reverse units I've seen just keep pressing the small moving piece in it while the controller knob is activated (and therefore, one knob activation(no matter how long it is)=1 reverse pulse, this one does not (this one "shoots").

I checked the spring, and tried, 1st to "harden" it, and then to "soften" it. No improvements so far. It seems that every time the reverse unit moves, it "auto-disconnects", goes back to "released" position, and works again, in a way similar to a doorbell.

Are you able to post up a photo or two of the internals so we can see the actual reverse unit and wiring?

Cheers

Cookee

Thank you very much for all your replies.

I'm attaching a couple pictures of the reverse unit and a video which shows what the problem is.

So far, I can not see anything wrong in the pictures (the reverse unit is wired like other reverse units which work just fine).

But check out the video and you'll see what I mean. The problem does not seem to come from the spring.

Thanks for your ideas.





And the video:

https://www.youtube.com/watch?v=4bE_MR0QjJ4

Just from the picture I reckon you've got the wrong spring on there - the adjustment arm is quite a long way back and the spring just does not look 'right'.

If the spring is wrong, you'll certainly get the symptoms you are describing because the magnet field is trying to overcome well beyond what it is designed for.

I need to recharge the batteries in my camera but I'll take a photo of my unit so you can see the difference.

That's my interim diagnosis anyway. Do you have a good working loco that you can swap the spring from to test? - you'll need to adjust the spring adjusting arm as well though.

Have you a copy of the Marklin Service Manual? - it could be helpful and there are links available to download it from.

Cheers

Steve

Attached is a photo of two loks side by side, a 3000 and a 3016 - I am now not so sure that your spring is wrong, but the adjustment certainly is and you should start with that.

You place the blade of a small screwdriver right into the corner where the extension comes out from the main part on whichever side you want to move the arm away FROM, then you VERY gently twist the screwdriver to make the adjustment.

So looking at your image, the arm is clearly stretching the spring too far which will mean the magnetic field is not strong enough to activate it properly.

CAUTION - Adjust it gently and in small steps - the metal is deliberately soft but is easy to break if forced too far. The idea is to move in small increments and test, then adjust further if needed.

Give it a crack and see how you go, I've also attached an image from a service sheet which shows perfectly what I'm talking about. You can view the full leaflet here....

https://www.marklin-user...ice/servicesheet1971.htm

Cheers

Cookee
Melbourne

Many thanks Cokee,

Unfortunately, as I wrote in a previous message, from the symptoms shown by the reverse unit it was unlikely that the problem had something to do with the spring, as:

If spring resistance is "too strong", the reverse unit will just not "reverse", or the reverse will be delayed so, before reversing, the locomotive's "jump" will be more noticeable.

If spring resistance is "too soft". locomotive will reverse at half throttle.

In any case, the reverse unit will not "shoot" like in the video attached.

"just in case", I removed the spring and tried with some other springs, softer and stiffer, just to check if there was some noticeable improvement. As expected, nothing improved, and the reverse unit continued "shooting" no matter how the spring was attached, or which spring was used.

This morning I've been checking the unit and I've noticed that if the reverse unit was hold from the coil, the problem disappeared.

Further experiments have shown that a little pressure on the coil side (the place where the black cable gets into the coil) makes the unit work properly.

So it seems that the problem is that the contact between the black cable and the coil is somewhat "random". I have solved it (at least for now) by using a little strap around the coil, making it a bit tight. Now it works fine with the original spring.

On Reverser problems...analog Loc's. Maybe "wrapping the wires tight" actually is a sign of a brush problem...and wrapping pushes the little brush springs a bit and makes them better contacts. A Story....FRO. from just today...I just had a problem with an old 3000 that I just got from Trainz. I was setting up for G-kids and 3000 fell off track at a bad spot. Tipped over. Now 3000 didn't run. Lights OK, solenoid worked. Fiddled with manual lever arm on reverser because engine would sit and vibrate...solenoid trying to engage. Looked at reverser leads off driver windings and wires were pretty fried right at junction. Solder job? I'm no solderer. Avoid avoid. Me think hard, save soldering job for others. Looked at wiring diagram and probed for continuity. Thought about the 3000 circuit diagram I had. The two coils share a common solder joint...the "main solder joint". Power was distributed from there. Looked at Main motor solder joints and resistors. I was getting 400 ohms on various places when I should have gotten zero or sometimes many more. Other loc's showed many more in same spots. On powered track.. Milli-amp meter said some power was getting to the main windings. I could see solenoid got plenty and from the shared "main solder joint"...but only when I gave the track the 24volt goose. Light was really bright and solenoid arm activated fine...must be getting taking too much juice and trying to activate itself. 3000 sat on track, light on and just buzzed softly when I let up on Tranny. I could make buzz stop with my finger. I could even "help" the gears turn with my fingernail but lok would not move. OK...seemed some power was on the rotor...but not much. Bad field coils on main core? Looked hard. Nope...just those stupid fried leads. Were they leaky?...well, they both had a little voltage...9 volts but no real current..moving reverser didn't change anything and reverser ground still provided good continuity. I couldn't test leads directly without scraping off gooey insulation but I kept getting something through the leads...that would be resistance and a few milliamps right on the solder joints and on the activator ground piece that the main solenoid arm moved that cam thing that sits on a vertical spring. Cam itself provided alternate ground to field windings and there was no resistance to ground. It wasn't a grounding issue. Hmm...Was it a current distribution issue? Main rotor windings and core windings not taking their share and solenoid had to take up the difference. A current division thing. Not sure the details but seemed likely. Then I saw those little brass springy things by the resistor just off the main solder junction....OMG....those must be the rotor brushes...hmm...bad contact...bad brushes? (like I'm an electrical person?...never had a circuits class in my life...just a few Ohms and Ahs from monkying with my Marklin as a kid (seriously) and then suffering through it in Physics and math). Nothing made sense until I remembered the 3000 stopped when it fell on right side. That was the Brush side...AHA...the Brushes were loose! One lost partial contact with rotor!...That was were the resistance was actually developing. Couldn't test brushes though...I looked and saw the springy things...wasn't in its little brush groove...the spring wire itself was too long. It simply hit the side of the brush housing and the brush rattled loose when the train fell over. Now that's an issue for a rehab person putting in brushes....hint hint! How much current distribution do you get? So, the way the reverser works is that the spring and spring lever arm must be balanced with respect to the forces developed by the main motor at 24 volt stall. So, if the brushes get less contact, the main rotor gets weak and the solenoid winding potential takes on extra potential at all times and buzzing happens if lok stalls and you get max current flow. The electromagnet would try to activate very gently at 60 hz! Yes...I see it all now..the solenoid arm spring lever-arm can be bent to compensate for changes in power distribution so that the reverser works in balance. Like a teeter toter...one side goes up the other goes down and the main solder junction is the pivot. Or so I think. So, for me..the reverser in the 3000 evidently had enough potential to buzz but not activate. That meant the Main coils were "too light" and the reverser side bumped on the ground. Well, once I saw the spring actually hit the side of the little brush holder and wouldn't do its job that is...making the brush touch the rotor hard enough to get contact and take its share of energy (weight), I took tweezers and nail cutter dikes to the end of the wire and "gave it to the cat". I Cut off 1/128 th in. Moved the copper mesh springy one a bit and it was OK. Put frame back on track and PRESTO CHANGO! It worked. Yay...and for all those out there...analog is fun too.