[GreenKeys] T100 garbling problem...

[Duncan Brown]

Ken,

Yes, the SM current is 40ma.

Yes, I am aware that 20-60 Ma SMs need ~120 VDC to overcome the 
inductance of the coils. [There are some systems (MITE) that used 24VDC, 
but about 250ma SM current.]  I was surprised to see the 20VDC reading 
as the open-loop voltage, since it was working so well (when cold).  So 
I was wondering if Siemens was doing something different.

The T 100 plugs directly into the T-N Telex box, so would need to change 
the connector to plug it into another loop supply, but I may have to do 
that.

There is no schematic in the T-N box (just a lot of relays & 
transformers) and I have not been able to find anything on the Internet 
about it.

So I'll check for AC ripple on the loop and clean the SM armature (they 
don't use "holding magnets" like some M15s did, do they?) before I dig 
into the T-N box.

Thanks,

Duncan
K2OEQ


On 04-May-17 12:43, Kenneth Gartland wrote:
> Hi Duncan and all!
>
> Re: the garbling issue, is the current being delivered to
> the selector magnet running at or very near 40ma?
>
> Remember, these electro-mechanical selector assemblies
> require a minimum voltage to operate properly!
>
> Any Siemens dial boxes I have worked on such as
> the NLC, NL, and L, always provide 60VDC @ 40ma to
> operate reliably in the local mode!
>
> The dial box you mentioned, I am not familiar with...
> perhaps it's operational specs are different...
>
> Hopefully, your dialer box has a schematic diagram inside
> the case as the Siemens units do, so you may check
> the local voltage and current conditions in "Cold" mode, and
> after it has been running...
>
> I still say, the teleprinter shud be tested directly on a known
> good 60VDC (Minimum) @ 40ma external loop supply,
> and then check for performance...
>
> As said earlier, does not hurt to carefully clean the armature
> and magnet pole face, making sure the armature is in it's
> fully released spacing position before doing so!
>
> Good luck!
>
> Ken
> VE3-HMQ
>


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