[GreenKeys] strange printing with LPR?

[WA5CAB at cs.com]

Eugene,

I don't know what kind of loop supply you are running and if you said it's 
the one that comes with a 28ASR I still wouldn't know, having owned M28 stuff 
but never used it.  But the first thing I'd do would be to patch a 0-100 MA 
meter into the loop (everyone really should have one permanently installed but few 
do) and check the loop current.  It should be either 60 MA or 20 MA with 
nothing being sent, whichever way your machine is wired.  Sounds like your typing 
unit may be more sensitive to it than the reperf.

And depending upon what type loop supply you have (upstream voltage and 
current setting type), you may have to always adjust the loop current anything you 
go from one to two sets of selector magnets.  Usually, with a 120 VDC supply, 
the change is minimal but I've heard some on here claim 40 volts is plenty 
(which I don't agree with but that's another story).

In a message dated 8/25/2006 6:26:05 PM Central Daylight Time, 
ehertz at tcaf.org writes: 
> Ok, so my next problem.  I have not been punching tape with my M28ASR in a 
> few weeks since the tape jammed and I was too lazy to clear it out. So its 
> been a while.  Today I cleared the jam and was printing off ITTY very well.  I 
> decided I would try to punch some tape off the loop. In my ASR it has a local 
> loop supply that is keyed with a relay from the external loop.  Everything 
> was working fine until I switched in the typing reperf (yes I have the reset 
> bail manually cleared from the code bars). I should mention that the main knob 
> is in the K mode for this.
> 
> When I do this, the reperf perfs perfectly fine, however the printer which 
> is now in series with it, starts to print junk.  When I take the LPR out of 
> the loop it returns to printing normally again.  I have a switch at the 
> operators position of the ASR to switch the lpr into the loop.
> 
> Any ideas? Whats baffling is that the reperf perfs away correctly, not a 
> missed character. I would think that if the loop was being bogged down somehow 
> by adding in the lpr that both the printer and the lpr would be degraded. 
> There is an adjustment for the internal loop (I have never tried to measure the 
> internal loop voltage) but I wonder if I may need to tweak?
> 

Robert Downs - Houston
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