[GreenKeys] M28 reperfs

[Daniel Jones]

I wonder if the navy used both Chad and Chadless in these units.  My TT-253A has the chadless Reperf.  

Looking at the case I wonder how they dealt with the chads in units with the full punch.  

If you need more print heads let me know I have 50-60 still on hand from the batch I made a couple years ago and I can throw a few in an envelope for you and send them your way.  

Daniel

Daniel


www.K6YIC.com
DJones at K6YIC.com
HH#11973

> On Jun 2, 2025, at 19:54, Duncan Brown <duncanancy at earthlink.net> wrote:
> 
>  Is there a document that lists all the different M28 reperf "LPR" models and  what is different about each?
> 
> I'm working on a TT-253A (thanks to Nick!) that does not have a standard reperf in it.  The TT-253A is supposed to use a LPR53AWA (full perf, tape feed out, backspace).  What is in this unit is a LPR13XXX (chadless, tape feed out, no backspace). The unit punches fine (after I re-hooked up a spring in the Selector Magnet area), but can't check the printing yet due to missing print hammer (one on order from Nick).
> 
> In checking out the "Tape feed-out" function - the tape feed-out solenoid operates (and buzzes) and the ratchets turn but no tape out. I think this is the version that tape-out is suppressed by incoming message (there is an arm going up towards the SM armature), but can't see why it is not releasing the function clutch when running closed.   
> 
> Also confusion between different manuals about whether the tape feed-out solenoid is supposed to operate on 115V AC or 115V DC.  1963 vintage manuals (eg NAVSHIPS 94456) show TT-253A using LPR53AWA reperf with solenoid L5850 (TC # 274); 450 ohms; 115VDC. Wiring diagrams show the LTRK5 base with a series resistor & diode and parallel capacitor to supply the 115VDC. But this LTRK5 base has the resistor & diode replaced by wires and the capacitor removed.   
> 
> I thought that the removal of the 115VDC parts could have been a later modification. (Besides the change of LPR unit, this TT-253A had the power & signal lines soldered directly to the blue Amphenol 16 contact ribbon connector!) (I've ordered the mating connector)
> 
> Then I got a hold of the NAVELEX 0967-LP-616-7010 (APR 79) manuals and they show the LTRK5 base and LPR53 wired for 115VAC!!  
> 
> I'm getting confused!
> 
> The reperf in this TT-253A is a LPR13XXX, with a tape-out solenoid #252 and measures 200 ohms and it does not look like any of the drawings in any of the manuals. (Pictures enclosed)  I've read how the tape-out mechanism is supposed to work, but had trouble following it, especially in that my unit seems different from what the manuals are talking about.
> 
> When I energize the solenoid, the timing ratchets rotate, but nothing else happens.  I've tried pushing & pulling (gently) the various levers in the area, but nothing trips the function clutch. I'll put in the parts to put DC on the #252 solenoid, but I don't think it will affect the tape-out.
> 
> This dissertation was partly just to get my thoughts & facts together, but if anyone has any ideas about the tape-out mechanism, I'd like to hear them.
> 
> Thanks,
> 
> Duncan
> K2OEQ
> 
> 
> 
> 
> 
> 
> <LPR13XXX tape-out side.jpg>
> <LPR13XXX tape-out top.jpg>
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