Bally em ( Camelot) 1 point relay energizes and stays on, until turned off.

[lanternau]

Hey guys, Just sorted a problem that was giving me a degree of grief. When the 1 point relay was energized from the play field the relay held in . I disconnected the PF , cleaned relevant switches...... no good. When I  manually energized the relay it sometimes stayed energized. Turn machine off and on , it lets go. I put a piece of cardboard between the plate and the coil..BINGO. It would appear that the plate is magnetized. I have heard that if you disassemble and wack it with a hammer it may sort the problem . I wrapped some electrical tape around the plate , works beautifully. Not broken now....I will see how long it lasts.
Cheers   

[Marty Machine]

Yep, relays (and all solenoids) can become magnetic after long periods of use.

There's a few ways to demagnetise steel parts, try google, anything from degaussing wands, north/south magnet poles and whacking it as u said.
IF youre gonna whack it, make sure the longest part of the steel plate is facing in an east/west direction.
If it's facing north/south, you're only gonna turn it into a magnet, which is why large steel ships are NEVER built in a north/south direction.

.....as Michal Caine would say...."not many people know that...."

MM

[ddstoys]

Are you serious Marty about the ships?


     I'm sure ill have another relay plate if you need one just post a photo so I know what type you need

[Marty Machine]

Are you serious Marty about the ships?

YEP 100%....back in the days of full steel ships (titanic, bismark etc etc) where ships are riveted together, the banging of the steel walls (facing north/south) changes the steel's magnetic properties since it's in the north/south (magnetic) earth axis...
ALL ships were later made east/west to minimise magnetic offsets within the ship, obviously this is a big prob with the onboard ship compass etc...

No doubt it's all on google somewhere :-)

For the home experimenter, go grab an old steel spanner or length of steel rod, even a screwdriver shaft (preferably it's already non-magnetic) and lay it on the ground facing true north/south....then bash it with a steel hammer (not sure how many times or how long this takes) but the spanner should then become magetic.
( i think it has to be pure steel and not a forged cast spanner etc?? )


MM

[ddstoys]

WOW AMAZING STUFF

[Strangeways]

Are you sure it is magnetized ? If it were, then switching the machine off should not solve the problem.

The 1 point relay is activated via the playfield switches. If it is staying on, than means there's a switch on the playfield that is shorted. There is a set of contacts on the 1 point relay than "hold" the coil "on". These need to be gapped correctly or the relay will appear to stay energized.

If it is magnetized, it would stay "on" all the time.

I would try a simple test.

Fire up the game. Push the 1 point relay "on". Does it stay energized ?

YES = The replay needs to be adjusted.
NO = A Playfield switch is getting stuck, shorting out the switch. Go through each 1 point switch.

[lanternau]

Thanks guys for all you feedback ! Mmm . The plot thickens. I have checked the play-field , it doesn't appear to be the problem. I played the machine for about an hour last night with the electrical tape in place ....didn't miss a beat . Remove tape ....problem back. I have checked the reset switches they seem to be fine .Was that what you were referring to Strangeways ? It would appear my fix is only a band aid repair and I would like to sort out properly as this seems like the last of many issues which I have wrestled to the ground. Well ...until something else comes up anyways.
 

[DSB]

Interesting about the ships. I didn't know that but as Strangeways has said if the relay drops out as soon as power is turned off then its not a residual magnetic problem. Just a thought but could the tape be holding the contact plate up enough to allow the the score contact to activate but is not allowing the hold in/latching contact to close. I don't have a wiring diagram and are assuming the score and latching contacts are separate contacts on the same relay? I would try putting some paper or similar between the latching contact only to see if that has the same affect as the tape.

[Retropin]

I have had this problem before with a couple of machines and a bit of tape between coil and plate does in fact fix the problem until a new plate can be installed.
Heres my theory ( I emphasise theory )

After a certain period of time the plate becomes slightly magnetised.. you can prove this by putting a small lightweight object to it that contains iron.. it will have a certain amount of stick and youll feel the attraction etc of the magnet.. its only slight, but it is present.
When the coil fires it creates a high current pulling in the plate.. this high current is required to move the plate. When the coil deenergises it is not quite at zero potential.. most EMs use centre tap of the transformer as ground and its not true earth.. Edi currents and the such on AC create minor ripples in the voltages... the fine dust given off by any machine also contains very fine pieces of metal and it too can become conductive or slightly magnetic.
Because the coil never quite goes to zero potential (unless machine is turned off).. it is enough to just hold the plate in place causing the coil to latch on.. but it needs the high current through it to move the latch in the first place.
Result?.. machine is fine.. coil latches and wont turn off unless power is removed.

A new plate will sort out the issue and please do try holding a small screw ( must be the type that rusts) or similar to the plate to confirm a magnetic field.

Cheers!

Gav - enjoying AC theory

[DSB]

I have had this problem before with a couple of machines and a bit of tape between coil and plate does in fact fix the problem until a new plate can be installed.
Heres my theory ( I emphasise theory )

After a certain period of time the plate becomes slightly magnetised.. you can prove this by putting a small lightweight object to it that contains iron.. it will have a certain amount of stick and youll feel the attraction etc of the magnet.. its only slight, but it is present.
When the coil fires it creates a high current pulling in the plate.. this high current is required to move the plate. When the coil deenergises it is not quite at zero potential.. most EMs use centre tap of the transformer as ground and its not true earth.. Edi currents and the such on AC create minor ripples in the voltages... the fine dust given off by any machine also contains very fine pieces of metal and it too can become conductive or slightly magnetic.
Because the coil never quite goes to zero potential (unless machine is turned off).. it is enough to just hold the plate in place causing the coil to latch on.. but it needs the high current through it to move the latch in the first place.
Result?.. machine is fine.. coil latches and wont turn off unless power is removed.

A new plate will sort out the issue and please do try holding a small screw ( must be the type that rusts) or similar to the plate to confirm a magnetic field.

Cheers!

Good theory and worth exploring. 

[Strangeways]

I would be looking at the 1 point relay. My Aces High had a similar issue. Clean and adjust. There should be a set of contacts (NO Normally Open) that close when the Relay is activated via a switch. If this set of contacts does not complete the circuit then the 1 point relay will stay energized until turned off.

[ddstoys]

Post a photo of your relay and ill find you a replacement plate