Eureka Forestville Eureka

Discussion in 'Electric Horology' started by Ralph, Mar 20, 2006.

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  1. Ralph

    Ralph Registered User
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    Jan 22, 2002
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    I've had a friend's Forestville clock for a while and finally decided to tackle it.

    Some background, it was really fussy running when I was looking at it way back when and then it pretty much stopped running.....I pushed it to the side ....anyway Sunday, I decided in getting back to it. There were a number of faults, I corrected.

    I used epoxy to better insulate the right side of the contact flipper(?).

    I also made a new contact strap . I wasn't sure how it should operate and when I took it apart. It turned out the one in there was broken and the end was clamp captured in the insulating mounting block. I decided it wasn't made properly and came up with what I thought would be appropriate and would cause the flipper to toggle somewhat.....it worked out fine.

    It was finally running with about 180 degrees of motion. It ran for about an hour and stopped. ......in troubleshooting, I determined the coil was open. I removed and opened the balance assembly and discovered the coil wire broken from the silver pin contact on the balance. I repaired that and moved the shims/thrustwashers around to bias the balance toward the front of the clock....this was to give me a little more pin extending into the contact flipper. ..... I formed the hairspring so the coils were concentric and not touching and ran it again.... now it is running too strong and overbanking.

    Looking at the Shenton book, they mention a dropping resistor in the circuit... I don't have one. When I examined what I do have, they have one side of the transformer output going to the chassis and the other side has a .0047mfd and a .47 mfd cap in parallel to ground. It also goes to the contact. This has obviously been fooled with.

    I would like to know the resistor value and which cap is correct. I suspect one of the caps is superfluous.

    ...the clock also growls when the contact made. I was wondering if anyone has converted theirs to DC. Shenton's book mentioned that Henry Fried did that to some of the one's he handled. It would be an easy mod and I might do that.

    Alternatively, I might change the transformer arrangement and use a remote plug in the wall type transformer to make the clock a little safer. The modern transformers have a thermal fuse in them to prevent problems. These clocks are known as table burners, because if the contact hangs up closed, the transformer in the base can overheat and scorch whatever it is sitting on or worse.

    My question is , can someone describe the circuitry and component values, ie. resistor, capacitors..


    I sent a PM to John Hubby, but thought this might be a discussion of interest to the group.

    Thanks, Ralph
     
  2. Mike Phelan

    Mike Phelan Registered User

    Dec 17, 2003
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    Ralph
    The two caps in parallel will purely increase the value to 0.4747 mfd, assuming they both have correct values - unlikely. So the .0047 is redundant, and I would assume that the other one is connected across the contacts to reduce sparking. Anything from 0.1 to 0.47 should be fine.
    The same effect could be given by putting a resistor across the coil to damp the inductance, or a diode across the coil to shore out the back EMF. I did this on my Murday clock.

    A resistor in series with the supply just makes the solenoid less efficient, so I do not know what the reason for this is. (my Shenton book is not at hand at the moment - I am at work). Is it run by a 1.5v cell?
    HTH
     
  3. Ralph

    Ralph Registered User
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    Jan 22, 2002
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    Mike, the Forestville Eureka runs off of the mains... line voltage here in the USA. 120VAC. It has a step down transformer in the base. I meant to document the no load output and loaded output voltage of the transformer.... I think it was 10VAC no load....if memory serves me right.

    The clock in it's native form does not use DC.

    The caps are not across the contacts. They are across the output of the transformer.

    The reason I am interested in the dropping resistor is that the clock is running too strong right now. I can solve it a number of ways, but thought I would solicit information on the original configuration.


    http://www.astro5.com/ACLibrary/fveureka.jpg

    Thanks, Ralph
     
  4. eskmill

    eskmill Registered User
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    Aug 24, 2000
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    Hi Ralph. The 0.47 capacitor as configured is really not helpful except to make some heat.

    The other smaller capiacitor, the 0.0047 is probably there to attempt to quench any spikes passed through the transformer from the mains.

    Why not dig out your variac and try reducing the input voltage? It's easier than inserting resistances in the circuit.

    I have no access to a Forestville Eureka but recall the examples I've seen were in pieces and the wiring had been tampered with.
     
  5. Ralph

    Ralph Registered User
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    Jan 22, 2002
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    Hi Les,

    I can correct it easily enough, but wanted the option of reviewing the original configuration before going forward.

    I'll probably add a thermal fuse to the circuit, or disconnect the base transformer and go with the plug in wall type...which should have one integrated

    Thanks for looking.

    Ralph
     
  6. Mike Phelan

    Mike Phelan Registered User

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    #6 Mike Phelan, Mar 22, 2006
    Last edited by a moderator: Dec 7, 2017
    Now I see, Ralph. I was thinking it was like one of the Eurekas that run on a battery and have a large balance wheel.
    As Les says, the smaller cap is probably for removing spike suppression on the incoming mains.
    The larger cap, if there is a resistor there, will be present to get rid of some sparking from the contact, but I am surprised that there is not a diode to rectify the supply - the magnet surely must buzz?
     
  7. Ralph

    Ralph Registered User
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    Jan 22, 2002
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    Hi Mike,

    You are right, it does have an annoying buzz, when it is impulsed. The laminations on the transformer were rusting and separating. I thought that was the problem. I put some stiffener straps on it and clamped them down better hoping to improve it, but it still buzzed/growled. I talked to John Hubby in the past about his Forestville and his does not growl. I'm wondering if his might have been converted to DC. It would be easy enough to do. It might happen on this one yet.... I just wanted to review the original wiring configuration.

    There are also covers on the open part of the balance so the balance looks more like a disk with poising screws. The covers are easily removed and can make it look more like a conventional Eureka.

    Thanks, Ralph
     
  8. John Hubby

    John Hubby Senior Administrator Emeritus
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    Sep 7, 2000
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    Ralph, I was traveling when received your message. I've now looked at mine and it was originally built to be battery powered, three "D" cells in series. It has three battery holders wired in series, with a 0.2 microfarad/250 volt capacitor wired across the leads to the coil that appears original, still tests OK. I'm sure it is original, because the bottom cover has a series of notes written in pencil showing it was purchased new in March 1952, and new batteries installed in 1953, 1955, 1956, and 1959. From what I've read I'm sure the problem with transformer fires was known by 1951, this clock shows they had already converted to battery power about the end of that year.

    When I bought it in 1986, inside the base were three VERY dead batteries, had all leaked acid and had eaten away chunks of the base steel and corroded part of the brass cover (the base is made with a stamped steel inner part and a spun brass outer cover). I removed the gunk and soaked the base in bicarb for several days, then cleaned it up as best I could. Had to rebuild the battery holders, but no question they were original equipment. It has been running well ever since, modern batteries last about three years.

    The balance wheel makes just over 1-1/4 turns on fresh batteries, dies back to about 3/4 turn over the life of the batteries still keeping reasonable time. Below 5/8 turn it continues to oscillate but doesn't advance the motion works.

    I think the clock would run well using a modern 4.5 volt fused supply.

    I'll post photos later.

    John Hubby
     
  9. Ralph

    Ralph Registered User
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    Jan 22, 2002
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    Thanks John,

    Decision time.

    Cheers, Ralph
     
  10. John Hubby

    John Hubby Senior Administrator Emeritus
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    Here are the photos:

    First one is the base without batteries. Note the three holders (these are insulated from the base and wired together) and the heavy corrosion where each of the three batteries are positioned:

    191.jpg

    This shot shows the base with the batteries in place. The capacitor is seen clearly in both photos, wired across the positive & negative leads (same as across the coil).

    192.jpg

    Hope this will help.

    John Hubby
     
  11. Ralph

    Ralph Registered User
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    Thanks John.
     

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