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04-3-2017 10:15:03  #1


Olivetti 2400 won't come on

Hi,

Father in law gave me a "working" electronic typewriter. When it turns on all the green lights are on which the book says means a doors open. All the doors are shut and the interlock  gets pressed down (the switch which detects if a door is closed), unless there's more than one bit I can't see anything.

The machine clicks and it doesn't do it's beginning cycle of setting up. The carriage only moves when the powers off, I've looked carefully and the clicking sound comes from the left , the motor is engaged and electrictrified because the carriage won't move when you try to move it so the motor is on as it's resisting it  and the brass gear which turns the bigger carriage plastic gear moves fractionally when the clicks are heard. It doesn't always click but the lights are always on.

It's as if it's trying but can't do it's thing

Thanks

 

04-3-2017 19:02:21  #2


Re: Olivetti 2400 won't come on

Hello.
I'm not an expert with the 'typing wedges' but I have recovered several of them from the curb and I will often have the same problem you describe.
The machine powers up and 'wants' to self check and all that but just can't quite get it done.
I usually find that there is a build up of dirt or lint or hair or correction flakes etc...so that the machine just can't quite make it to the exact spot that tells the controller it is home.
I have found that if I can move the (type head ?) off the home position and clean with isopropyl alcohol on the slide rail and then dab some light oil ( I use something called Marvel Mystery Oil ) in the expected return path in hopes some will get inside the guide bearing of the type head to help wash out the scrunge .
Sometimes I'll have to do this more than once or twice but it usually yields good results.
Consider that the drives in the typical wedge typer are pretty low powered and it doesn't take much to hold them up.
Hope this helps
HABD!  

 

05-3-2017 12:55:16  #3


Re: Olivetti 2400 won't come on

Hi,

Thanks very much for taking the time to reply and try and help.

I did follow your advice as it makes a lot of sense, however, the rail was pretty clean and gunk free because the carriage moves across it (i.e you can push it) when the powers off (probably not a good idea but it must have some protection for this since the carriage cannot possible stay where it is all the time). It did shift some dirt though and lightly oiled it with gun oil. 

When the machine is on (and it clicks and the lights are all on), the motor is definitely powered up because the carriage is completely imobile against the motor gear, as soon as the power dies the carriage is able to be pushed.  I'm thinking its more of a either a circuit board fault (I did take off all the covers and check nothing was broken or fried), or its the optics sensor which sees where the carriage is.  I lightly cleaned the but I wonder if its failed and can't see the carriage anymore.

Trouble with electronic stuff is you can't always see the problem

I'm open to any more suggestions.

Many thanks

Richard

     Thread Starter
 

06-3-2017 18:50:38  #4


Re: Olivetti 2400 won't come on

Hmm.
When you say it's the optical sensor, are you sure it has an actual optical sensor?
I was thinking it probably just has a proximity sensor or even a crude magnetic switch (?)
What make and model is this machine?
When I re-read your post I see you refer to the 'Door Open' alarm.
I have a couple of Brother digital machines that do the same thing.
It usually means the clear plastic door/cover that encloses the platen and type carriage/rail is just slightly ajar because the machine is not sitting with all four feet on the same plane and the machine is twisted.
This may sound unusually sensitive but, I think something on this one machine I have that does this, may be cracked/broken and makes it very touchy.
Perhaps some further investigation.

 

07-3-2017 05:10:59  #5


Re: Olivetti 2400 won't come on

Hi,

Its an Olivetti ET2400 from 88 (I think)

I'm guessing its an optical sensor, two little glass eyes enclosed in a small electrical box.

It doesn't really alarm, in fact its never beeped once, just has all the lights on, but lately, its been having only some of the lights on, its basically random but 90% of the time all the lights are on. All the doors are closed and the interlock switch which detects if its closed is all working and complete.  Ive taken it apart and nothing appears fried or loose.

The machine is sitting flat and doesn't appear twisted.

Thanks

     Thread Starter
 

07-3-2017 16:58:27  #6


Re: Olivetti 2400 won't come on

That sounds like the optical sensors that I have on the machines I operate at work.
In my application the light needs to shine at a reflective surface so as to be detected and complete the circuit and generate the required response from the machine controller.
In some instances when a light beam is broken I'll get an alarm that may stop the entire line or just a part of it.
In other cases when a light is seen by a sensor it will trigger a certain response when the line is running in automatic mode. 
So your carriage is either breaking the beam or completing the path by reflecting it back to the sensor.
One way to test the sensor would be to cover the emitter and collector with a piece of dark paper when the carriage is in home position and see if you can fool it into thinking everything is good or you can try a piece of something highly reflective that will fit in between the carriage and sensor to get the same result.
I wish I could offer a better suggestion but the only thing I have that is close to your machine is a couple of Brother digital machines.
I'm not aware of any light sensors as with yours and I'm thinking they may even have an encoder wheel on the carriage drive to tell the controller where the carriage is.

 

11-3-2017 09:14:46  #7


Re: Olivetti 2400 won't come on

Hi,,

Thanks for your advice, I tried but nothing worked, however, I have worked out the noise appears to be coming from the motor which is under the carriage and moves the ribbon up and down.  The motor attaches to a plastic cam with a spirally shaped cam path which a plastic part follows and moves the ribbon up and down.  That part moves perfectly, its almost as if the motor is getting a confused signal. Its kind of pulsing

Cheers

     Thread Starter
 

18-3-2017 01:44:28  #8


Re: Olivetti 2400 won't come on

Has the machine got a new ribbon in, i seem to remember that the olivetti typecart ribbons had a optical reflector on them so the machine knew it was installed, i also think the machine sequence was to check the ribbon lift then drive the ribbon cradle to the left hand side to start typing. (sorry if this is vague but i have not worked on one of these for about twenty years) 




 

 

19-3-2017 03:38:15  #9


Re: Olivetti 2400 won't come on

Hi,

That's for your reply.

The ribbon isn't new but it has about 3/4 of the carbon left which
You can see through the viewing window.

I've tried starting with the carriage in front of the sensors and other places
But the motor of the carriage just clicks and nothing happens

     Thread Starter
 

19-3-2017 05:21:44  #10


Re: Olivetti 2400 won't come on

I used to service VCRs. They had a similar motor driven cam. Grease on the cam would harden and the small belt that connected the motor to the cam worm gear would slip. Typical fix was to replace the belt and degrease/relube the cam.

There was a mode switch in the mechanism that provided feedback of what position the transport was in. The contacts in the switch would get noisy. Sometimes just spraying it with contact cleaner would work, but other times the switch needed replacing. These switches were 4-bit logic, so they typically had five wires or connections.

I don't know if these typewriters use a mode switch for sensing the position of the print head, or an optical sensor. If optical, they could be clogged with grease or debris. Use a cotton swab and distilled water. Alcohol will damage the sensor optics.

 

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