[GreenKeys] Selector magnet question

[w9ddd at tapr.org]

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.
>> 
>> 
>> ---
>> This email has been checked for viruses by Avast antivirus software.
>> https://www.avast.com/antivirus
>> 
>> ______________________________________________________________
>> GreenKeys mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:GreenKeys at mailman.qth.net
>> 
>> 2002-to-present greenkeys archive: 
>> http://mailman.qth.net/pipermail/greenkeys/
>> 1998-to-2001 greenkeys archive: 
>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool: 
>> http://comcents.com/tty/greenkeyssearch.html
>> 
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
> 
> 2002-to-present greenkeys archive:
> http://mailman.qth.net/pipermail/greenkeys/
> 1998-to-2001 greenkeys archive:
> http://mailman.qth.net/archive/greenkeys/greenkeys.html
> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
> http://comcents.com/tty/greenkeyssearch.html
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>