[GreenKeys] Selector magnet question

[w9ddd at tapr.org]

No problem Robert,  I wasn't even thinking about pulling mags at the time I posted or I may have presented the situation clearer..

I guess I'll continue with the restoration of the rest of it for now since it some how still magically works and keep my eye out for a junker to rob magnet coils from.

John, W9DDD


> On Jan 3, 2019, at 2:11 AM, Robert Downs <wa5cab at cs.com> wrote:
> 
> Oops!  My bad.  Should have checked what 4196WD applied to before engaging
> keyboard.
> 
> Robert Downs
> 
> -----Original Message-----
> From: w9ddd at tapr.org [mailto:w9ddd at tapr.org] 
> Sent: Wednesday, January 2, 2019 06:11
> To: Robert Downs; greenkeys at mailman.qth.net
> Subject: Re: [GreenKeys] Selector magnet question
> 
> Hi Robert,
> 
> I should have mentioned that this is a 28.  As far as I know 28s never had
> pulling  magnets.  
> 
> With the high resistance of the bad coil, the loop was running at 42ma.
> I've since dropped it to 20ma,  I still get good copy on ITTY.  I haven't
> played with the range finder to see what that is.  I'm not expecting that to
> be good.  
> 
> John, W9DDD
> 
> 
>> On Jan 2, 2019, at 1:17 AM, Robert Downs <wa5cab at cs.com> wrote:
>> 
>> If they are the older larger round pulling magnets, they should be in
> Series
>> for 60 mA.  Pulling magnets cannot operate in a 20 mA loop.
>> 
>> Robert Downs
>> 
>> -----Original Message-----
>> From: greenkeys-bounces at mailman.qth.net
>> [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of John, W9DDD
>> Sent: Tuesday, January 1, 2019 14:02
>> To: greenkeys at mailman.qth.net
>> Subject: Re: [GreenKeys] Selector magnet question
>> 
>> Actually they are in series.  Not what it was supposed to be.  4196WD 
>> applies to this printer.  It shows the selector magnets wired in 
>> parallel and connected to a 35 pin male connector through a shielded 
>> twisted pair of wires.  Since the cable coming off the 35 pin female 
>> connector had only one shielded pair (matching that coming off the 
>> selector magnets), I blindly connected them to a 60ma loop.  Printer 
>> seemed to print fine, but I'm not running it full time yet since I 
>> haven't finished cleaning and lubing it.
>> 
>> Lesson, never assume factory default configuration.
>> 
>> I was looking at it in terms of what it would take to put the standard 
>> 21 pin connector.  That's when I noticed it wasn't wired as shown on the 
>> WD.  So I had been running 60ma through them as a series connection. 
>> Just to confirm the connection, I put on ohm meter on it and got 1500 or 
>> so reading.  I kept doubting the ohm meter, but finally determined the 
>> individual coils read as noted by fully disconnecting them.
>> 
>> Looking for corrosion will be my next adventure as soon as the company 
>> head out to the mall.  If that isn't it I'm hoping someone has a junker 
>> they're willing to take coils from.  Not sure why the parts book says to 
>> replace in pairs for the old design (which these are).
>> 
>> 
>> 
>> John, W9DDD
>> 
>>> On 1/1/2019 1:08 PM, Duncan Brown wrote:
>>> Are the coils in series or parallel? If parallel, the 135 ohm coil is 
>>> doing all the work!
>>> 
>>> The 1480 ohm reading is strange. Perhaps corrosion on a terminal or the 
>>> coil wire is causing the increased resistance? (ie, it is on its way to 
>>> becoming open)
>>> 
>>> Good luck & Happy New Year
>>> 
>>> Duncan
>>> K2OEQ
>>> 
>>>> On 1/1/2019 12:52, John, W9DDD wrote:
>>>> How can one of the two coils measure 1480 ohms and the other the 
>>>> nominal 135 ohms?
>>>> 
>>>> I can image a case of it being open, or shorted, but 1480 makes no 
>>>> sense to this old head.
>>>> 
>>>> Strange thing is I've been copying ITTY off an on as I'm testing 
>>>> various parts of my set up.
>>> 
>>> 
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