Electric 505 Short Circuit

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Frobob
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Electric 505 Short Circuit

#1 Post by Frobob » Sat Jun 10, 2017 11:51 am

So I had a theory for renewing the contacts on 505's: a dab of silver conductive glue. Unfortunately I slipped and made a connection from the contact to the staff. Did some research to see what could remove the stuff, and it's your choice of isopropyl alcohol or acetone. I knew the alcohol would dissolve the shellac used to hold the jewel in, so I opted for acetone, which took the silver stuff right off.
Problem is that the balance/coil tests fine until I give it full power. That makes it short circuit until I rinse the lower bits in acetone and water again, and then it tests fine until I impulse it, etc., etc...
I thought the electromagnet might be moving something to a bad position, so I tried demagnetizing just the balance. Same results.

I'm running out of ideas and sanity.

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pETE201
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Re: Electric 505 Short Circuit

#2 Post by pETE201 » Thu Jun 15, 2017 2:06 pm

I don't particularly want to be the one to burst your bubble........ BUT it ain't gonna work! :(
I have thought long and hard about all this, over the past 3 years, and the only workable, reasonably durable contact must be made of proper (precious) metal. And the harder the better.
Electrical contact in a 505 is made 9,000 times an hour (or nearly 79 million times per year!). I would expect epoxy to hold up for about 5 seconds at most, and in the process it would coat the index wheel with so much glue residue that you would lose conductivity altogether in a very short time.
The only option for a worn contact is either to find and fit a NOS one, which is do-able if you can work out how to swap the roller table. Or do as I do and make your own. Much more difficult, but they can be made with significantly harder alloy (220 Vickers hardness), so durability is greatly increased. My first test contact with this metal has been running for only 3 months, so the durability aspect is still to be proven.
However you go about it, replacing 505 contacts is a pain in the.............

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diveboy
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Re: Electric 505 Short Circuit

#3 Post by diveboy » Thu Jun 15, 2017 5:57 pm

Elgin had an answer on the contacts. I'll explain later in the year but they no longer had concerns for contact wear.
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JerseyMo
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Re: Electric 505 Short Circuit

#4 Post by JerseyMo » Thu Jun 15, 2017 6:59 pm

diveboy wrote:
Thu Jun 15, 2017 5:57 pm
Elgin had an answer on the contacts. I'll explain later in the year but they no longer had concerns for contact wear.
So did Timex - They bought it from Laco :) This 1961 back set is going strong!
DSC05371.JPG
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DSC05372.JPG (101.87 KiB) Viewed 170 times
“Someday, and that day may never come, I’ll call upon you to do a service for me. But, until that day, accept this justice as a gift”

Frobob
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Re: Electric 505 Short Circuit

#5 Post by Frobob » Fri Jun 16, 2017 8:58 am

It does make enough contact to function as of now, to the point that it was running before this escapade; the silver paste was just something I wanted to try.
Problem is that it shorts whenever the coil gets full power and continues shorting until recleaned.

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pETE201
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Re: Electric 505 Short Circuit

#6 Post by pETE201 » Fri Jun 16, 2017 2:36 pm

Diveboy, are you referring to the Elgin designed movements (722/725/910) or the later ones? Assuming you mean the earlier ones which were similar to the Lip R148 in terms of functionality, they still had contacts didn't they? I know that the Lips in my collection have generally needed replacement contacts if they arrived in non-running condition. This is why I bit the bullet and bought 10 NOS LIp movements a while back. I understand about the diode suppressing the sparking, but this was necessary because of the coil being of a bobbin style. The Hamilton coil design, being flat, negated the need for a diode because of its inherent resistance to sparking, as described by Fried in his book. Obviously, the contact on the Lip design is on the end of two tiny contact wires similar in style to the earlier type Hamilton 500 movement, so the contact pressure was much lower. It's the contact pressure which causes the excessive wear on the 505, compounded by the fact that the alloy used on the D-pin was really,I mean really soft. If you can replicate a D-pin in some decent metal, I doubt that contact degradation would be any faster than the other electric movements of the time.

JerseyMo- I can't quite see how the Timex contact works. Is it similar to the Landeron 4750, where it's more like a reed switch?

Thanks,
Pete

JerseyMo
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Re: Electric 505 Short Circuit

#7 Post by JerseyMo » Fri Jun 16, 2017 6:36 pm

See attached.
model 670001.jpg
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model 670002.jpg
model 670002.jpg (291.04 KiB) Viewed 123 times
“Someday, and that day may never come, I’ll call upon you to do a service for me. But, until that day, accept this justice as a gift”

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diveboy
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Re: Electric 505 Short Circuit

#8 Post by diveboy » Sun Jun 18, 2017 2:15 pm

pETE201 wrote:
Fri Jun 16, 2017 2:36 pm
Diveboy, are you referring to the Elgin designed movements (722/725/910)
yes, the later onese are not Elgin.
Assuming you mean the earlier ones which were similar to the Lip R148 in terms of functionality
Interesting statement that....

Elgin had to resolve the contact issue and they did.I have a reference they resolved the contact issue by using a platinum alloy mix, Whats the mix ? you would have to destroy a contact to find out but I wouldn't be surprised if it was a platinum/elgiloy mix as the people who brought us elgiloy were also involved in the electronic watch project.
Disruptive Elgin Collector.... 39.56043956043956
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pETE201
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Re: Electric 505 Short Circuit

#9 Post by pETE201 » Wed Jun 21, 2017 1:58 pm

Thanks JerseyMo and Diveboy for the additional information regarding the Timex and Elgin electrics/electronics. I am still a little bit curious about the typical lifespan of the respective contact arrangements of these movements. A Hamilton 505 with a NOS D-pin I would expect to run continuously for 12-18 months. Is there any comparative data about Timex or Elgin movements? Obviously the difficulty encountered in renewing the 505 contact played heavily against its practicality, whereas I know the Lip R148/R184 contact wires for example, were available as a simply replaceable spare part which remained available until relatively recently. It looks very much as if the Timex contact wire could be easily swapped out too. Is this correct?
Thanks

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diveboy
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Re: Electric 505 Short Circuit

#10 Post by diveboy » Wed Jun 21, 2017 2:31 pm

well, the elgins are interesting in that everyone that has a view on them, doesn't actually own one (well about 95% of them).

All 40 of mine are on their original contacts, some of the gold filled cases have wear, indicating a nice and long service. of the 40, 3 don't currently run which I'm working to resolve, I think thats the first documented case of how they are ageing.

I've been wearing one for two days now and just stopped to wear different model for a WRUW theme, tomorrow its back to the electronic.

I have been wondering if the LIP could take the Elgin contact wire, wouldn't that be interesting if it could ? wonder were LIP got the coil design from ? or the diode ? in fact, wonder how lip re-engineered their electronic in less than 4 years from the R27 to the R148..... considering they are two completely different principles of operation, wonder who had the knowledge of both systems at that time.

lots to ponder on that.
Disruptive Elgin Collector.... 39.56043956043956
http://www.elgin.watch - Elgin Model Database
instagram @elgindownunder

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