Completely New To Hobby... Feeling Completely Helpless with my Leich 901B

[Joel B]

Alex- Thanks for hanging in here with me... I know how hard it is for me to learn this via pictures, so troubleshooting that way is even more so.  If there are specific things you want to see I am happy to zoom in.

I Disconnected all 3 of them (5, 13, 2) and it still cranks the same and does not ring.

[Alex G. Bell]

Alex- Thanks for hanging in here with me... I know how hard it is for me to learn this via pictures, so troubleshooting that way is even more so.  If there are specific things you want to see I am happy to zoom in.

I Disconnected all 3 of them (5, 13, 2) and it still cranks the same and does not ring.

For something this complex and constructed the way it is, photos are not likely to help me.  I can't speak for others.

Since I had you disconnect the magneto, of course it cannot possibly ring.  But since it does not crank freely even with the magneto disconnected there either is a short circuit internal to the magneto or mechanical interference.  Perhaps you swapped a longer screw for a shorter screw or differences in the thickness of the baseplates causes a screw to now be too long so that it is projecting into the magneto and either mechanically interfering with its turning or shorting it electrically.

However I don't see how this could change between the first cranking after reassembly and a subsequent one.

[Joel B]

Alex- It's worth a try.  I saved the original screws (minus the two that were bad) that I can try rotating back in around the magneto. and other areas.  I'll start tackling this tonight and tomorrow morning and post back tomorrow. 

I appreciate all the help from the group.  Looking forward to having this solved and being able to post some sort of finished project to the forum!

[Alex G. Bell]

Alex- It's worth a try.  I saved the original screws (minus the two that were bad) that I can try rotating back in around the magneto. and other areas.  I'll start tackling this tonight and tomorrow morning and post back tomorrow. 

I appreciate all the help from the group.  Looking forward to having this solved and being able to post some sort of finished project to the forum!

Better yet, try removing one mounting screw at a time after another until all are removed, cranking it after each is removed to see which screw (if any) has an effect.

[TelePlay]

For me the photos only demonstrate the impossibility for me of helping you based on the photos.  For me the schematic is a "map".  The photos are a maze.

That's true, in this instance, but I'd bet that somewhere down the road someone gets a 901B with a problem and may find these images to compare with what they have. Leich phones are not that common and fewer members know them really well to solve a problem by looking at only images but images always add something to a topic. They may not be useful here and now but may be of use long down the road.

Thanks for posting the pictures and hopefully Alex, or someone with a Leigh schematic, will be able to help.

[Alex G. Bell]

That's true, in this instance, but I'd bet that somewhere down the road someone gets a 901B with a problem and may find these images to compare with what they have. Leich phones are not that common and fewer members know them really well to solve a problem by looking at only images but images always add something to a topic. They may not be useful here and now but may be of use long down the road.

Thanks for posting the pictures and hopefully Alex, or someone with a Leigh schematic, will be able to help.

I agree that the photos may have longer term value even though not for me in the immediate case. 

Their reference value however depends somewhat on whether the set is properly wired, which remains to be determined.  They might instead help someone recreate the problem Joel B. is having.  Time will tell.

The diagram is what I would call a "wiring schematic" since it shows physical wiring details while also including internal electrical details of the components, making it possible to understand and troubleshoot the circuit.

I've been colorizing the left hand (magneto service) figure in the diagram to make each of the functional paths more readily identifiable so they can be followed visually for troubleshooting.  I will post it when it's beneficial to continuation of the task at hand: when Joel B. has replied to the last suggestion.

[TelePlay]

There is a pdf schematic of a 901 phone attached to this post.

     http://www.classicrotaryphones.com/forum/index.php?topic=7984.msg87635#msg87635

Don't know if it THE right one but it's at least close.

Screen capture of the pdf file is attached as a  jpg.

Schematic looks like a good copy of an original Leich Schematic attached to this post

     http://www.classicrotaryphones.com/forum/index.php?topic=11513.msg122803#msg122803

[Joel B]

Teleplay- That is the schematic, and I have a copy that was on the interior of each of my phones.

Alex- I used your suggestion and worked through the mounting screws, removing them one by one and trying the crank after each. Unfortunately, the problem still remains.  But I guess that should tell us that we've narrowed the problem...right?  I'm trying to channel some inner Edison here ("I have not failed. I've just found 10,000 ways that won't work.") 

I then removed the wires to 5, 13, & 2) and again gave it a crank, but again the magneto is tough to turn.

Is it safe to say that the problem then seems to be with the magneto?  Could something I did make the magneto irreparably damaged? Or is there something else to do with the magneto to "reset" it after a short.

I appreciate you color coding the diagram for me.  I'm attaching something I drew up after spending a day mapping all the wiring in my 2 good phones.  May shed some light.

All- I know many of you don't have experience with a Leich, but when you have replaced bad magnetos in other phones, are there things you did to make sure that process went smoothly?  Things I should be adhering to here?  Things a newbie (like me) is likely to stumble on?

Again, thanks for any help you can provide.

[TelePlay]

This may be a stupid questions but

1) is this what your magneto looks like or is it the side mount type, and

2) even if not have you tried to clean and oil the magneto?

Could be something broke loose and is jamming the mechanism or just needs lubrication. I've never worked on one of these but have seem the WE mags worked on and old grease in bearings can get hard.

May be way off here but needed to ask.

[Joel B]

Teleplay- Yes! That magneto could be the twin brother of mine.  I will try cleaning and lubricating it as well.

[Joel B]

Teleplay- I had the magneto out from my previous steps, so I cleaned and oiled the magneto.  One thing I noticed is that when I remove the contact on the base of the magneto it spins freely, while when I let it down to make contact the magneto again cranks harder, which makes sense to me because it's passing a current.  Right?

I've decided to keep working on this all morning as I've got it out on my desk, so if others have ideas I'm happy to try them!

[TelePlay]

Teleplay- I had the magneto out from my previous steps, so I cleaned and oiled the magneto.  One thing I noticed is that when I remove the contact on the base of the magneto it spins freely, while when I let it down to make contact the magneto again cranks harder, which makes sense to me because it's passing a current.  Right?

I've decided to keep working on this all morning as I've got it out on my desk, so if others have ideas I'm happy to try them!

Well, you've narrowed down the problem a bit by eliminating the physical mechanism being jammed. What you said sounds right but Alex, when he gets on line, will be more helpful with the electronic/current issues. I'm not that familiar with mag phones.

Did you read through this topic

     http://www.classicrotaryphones.com/forum/index.php?topic=11513.0

of a member who worked on a hard to turn magneto? Don't know if there is anything in there that will help you other than that one was hard to turn as well.

[Joel B]

Teleplay- I had in the past when I first started this project, and just did again.  The post by DSK seems to be the most promising (http://www.classicrotaryphones.com/forum/index.php?topic=11513.msg122803#msg122803), but I would need him to explain it.  He and I were messaging yesterday and I know he's headed out on holiday.  We'll see if he can shed some light when he's back.

[Alex G. Bell]

TeleplayOne thing I noticed is that when I remove the contact on the base of the magneto it spins freely, while when I let it down to make contact the magneto again cranks harder, which makes sense to me because it's passing a current.  Right?

Comparisons with other message threads about conventional older style magnetos may not teach anything very useful.  Although the operating principles are the same, the problem which suddenly arose with this one probably comes down to something about its specific mechanical design, which don't necessarily occur with older ones, rather than to the principles of operation which apply to all of them.

Addressing the topic of the contacts on the back: 

Please elaborate on what you mean by "when I remove the contact". 

It's more accurate to say that like any generator, the mechanical load required to turn it depends on the current flowing through the output, current it is generating.  So loosely speaking it is "passing current" but most would probably understand that to mean that something which is passing current is allowing current from an external source to pass through whereas this is generating the current. 

The presence of a short circuit across the output is the condition where the current is the most it can be therefore the mechanical force required to turn it is noticeably much greater than normal.

If the mechanical load presented by a generator (force required to turn it) did not increase with electrical load you could get electrical energy "for free" without investing mechanical energy and perpetual motion would be possible: a generator producing current to drive a motor which turned the generator, running continuously of their own accord with no power applied externally.  This is called "perpetual motion" and clearly is impossible, though many have tried.

That contact on the back short circuits the magneto until the crank is turned.  There is a mechanism in any magneto, usually a split in the main shaft with a wedge shaped end, which causes the contacts on the back to operate when rotational force is applied to turn the crank.  The contacts remove the short circuit by pressing the center contact away from the contact it touches while at rest (closer to the body of the magneto) and connecting its output to the line when the center contact touches the back contact. 

A side view photo showing these contacts and the end of the shaft which drives them might be beneficial.

Are these contacts operating when the crank is turned?  They should operate merely when pressure is applied to turn the crank before it actually turns.

[Joel B]

Alex- I shouldn't have said remove the contact, I meant when I pull the contact away from the post.  See the pict attached.

I also provided a couple of closer pictures showing the underside of the magneto.

I'm not sure I understand your last question. "Are these contacts operating when the crank is turned?  They should operate merely when pressure is applied to turn the crank before it actually turns."

How am I able to tell if they are operating?