Shadow Graph Problem - Printable Version
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Shadow Graph Problem - joybird - 04-23-2016
This is out of an Early Philco 16B Cathedral (121)
It differs than the one shown on the Repair Bench
http://www.philcorepairbench.com/tips/svctip01.htm
The Magnet is different.
The Coil checks good 825 ohms.
The Vane is free and moves easily.
I did oil it to free it up
It seems the Magnet has lost its magnetism.
No easy way to try to re magnetise.
Should I remove the Rivets ???
That way I can get the magnet out.
The Rivets are Brass, so i assume the replacement one have to be brass. ??
Anyone run into this Type of Shadow Graph?
Bob T
RE: Shadow Graph Problem - morzh - 04-23-2016
Usually you rub a strong rare earth magnet agains it. It does not need to be very strong.
RE: Shadow Graph Problem - joybird - 04-23-2016
Won't work unless I remove the magnet.
No room to move another magnet around, Vane also in the way to try that.
I am wondering if anyone else has seen this type.
Bob T
RE: Shadow Graph Problem - Eliot Ness - 04-23-2016
Those magnets are pretty small, and it looks to be plenty of room to get one in there. I used magnets for slot cars that were very strong and very small.
RE: Shadow Graph Problem - morzh - 04-23-2016
The magnets can be as small as 1.5mm in diameter. We have those.
RE: Shadow Graph Problem - joybird - 04-23-2016
(04-23-2016, 07:31 PM)morzh Wrote: The magnets can be as small as 1.5mm in diameter. We have those.
Thank you guys. I just ordered some of those rare Earth Magnets, 3/8 and 1/4 Will try
How do you recommend I apply them some on each end of the horseshoe?
Or just One position
Bob T
RE: Shadow Graph Problem - radiohenry - 04-24-2016
What about the sticky backed magnets used for crafts ? You can cut it to fit and its not very thick.
Henry
RE: Shadow Graph Problem - joybird - 04-24-2016
I am a little worried.
I put a strong magnet ( the 1/2 Magnet used to pick up parts), near the Horseshoe. The Vane does nothing.
I would expect it to go towards the Magnet. ?????
The Vane moves freely on its axis, The coil is in place.
But shouldn't the Vane react to a magnet. Move left or right????
Wonder if more is wrong than just a weak Horseshoe Magnet.
I believe when power is removed from the Coil the Vane should park itself according to the strength of the horseshoe Magnet.
Anyone work these before?
The Article on the Work Bench sounds pretty simple to test these.
Bob T
RE: Shadow Graph Problem - morzh - 04-24-2016
Vane is not magnetic, it is attached to a magnetic armature.
http://www.philcorepairbench.com/tips/svctip01a.htm
RE: Shadow Graph Problem - joybird - 04-24-2016
(04-24-2016, 10:51 AM)morzh Wrote: Vane is not magnetic, it is attached to a magnetic armature.
http://www.philcorepairbench.com/tips/svctip01a.htm
I have read that article and realize the Vane itself is not Magnetic.
It does ride on a Metal Pin (Armature) The Pin is aligned between the magnet ends
See this
https://www.youtube.com/watch?v=IzRFEhuu0HE (KEEP in mind this one is mechanically different than mine)
Mine does not deflect at all with Magnet applied to side with coil energized or de energized
The light source is just to cast a shadow, as far as I know it does not effect Vane movement.
The Metal Armature is not being effected by a Magnet. The Top of the Armature is oval , like a race trrack.
The ends of the Ova armature align with the ends of the Horseshoe shaped magnet
I can't figure why the Armature does not respond to a magnet in its path. I would think it would follow a magnet,
Learning.
Wish some one with the same one would jump in. This must be a very early version, I see they replaced it soon into production. The Type in the YouTube seems to be more common.
Bob T
RE: Shadow Graph Problem - Eliot Ness - 04-24-2016
Bob, while not the same style as yours, this thread might shed some light on troubleshooting problems in a Shadow Graph:
http://philcoradio.com/phorum/showthread.php?tid=14309
Sorry I can't be of more help, but the only Shadow Graphs I've messed with were A.K. and Zenith, and all of those S.G.'s basically worked when I got the sets.
RE: Shadow Graph Problem - joybird - 04-24-2016
(04-24-2016, 12:06 PM)Eliot Ness Wrote: Bob, while not the same style as yours, this thread might shed some light on troubleshooting problems in a Shadow Graph:
http://philcoradio.com/phorum/showthread.php?tid=14309
Sorry I can't be of more help, but the only Shadow Graphs I've messed with were A.K. and Zenith, and all of those S.G.'s basically worked when I got the sets.
Thank you John.
This looks like it was the first type Shadow Meter they had on the 16B. They did change it fairly quick.
The one I have, it seems the horseshoe Magnet is 1/2 the thickness and the later Versions. Like shown on the YouTube Video.
What bothers me is that the armature does not respond to any magnet.
I will wait, maybe the tiny magnets I ordered will fit better.
Looking real close at mine . The Armature is not aligned with the end of the Horseshoe at one end. The other end is aligned perfect. Also I see rust on the tips of the Horseshoe I have.
Nothing to loose here. If the new Magnets do nothing I will attempt micro surgery
Mean while I am in need of a complete Shadow Meter.
Will Post
Thanks for the help
Bob T
RE: Shadow Graph Problem - joybird - 04-24-2016
Just learned My 16B is the earliest Version Prior to 11/1933
In a Change Bulletin (Parts Listing) Dated 11/15/1933
it states The Shadow Meter P/N 6497 , is to be replaced with P/N 45-2028 on all chassis after 12/20/1933
Quite evident this P/N 6497 was a poor performer.
Happy in one respect, I have a VERY early production 16B Version 121.
BUT
I am sure there will be a lot of changes to incorporate in it.
It is a Rusty Nasty Mess, just up my alley.
Bob T
RE: Shadow Graph Problem - morzh - 04-24-2016
The rewards are so much sweeter when they are toiled for.
RE: Shadow Graph Problem - Phlogiston - 05-02-2016
What are you using to energize (polarize) the coil?
Does the end of a non magnetized screwdriver stick, at all, to the shadograph magnet?
I can tell you one thing. The bulb holder in its current position is going to cast a shadow way off center. The filament must be centered on the hole.