I hate electrics

[Grahamshed]

This gets a bit involved
I have a lathe with a video camera over it feeding to a TV - No problems, everything works fine.

I now want to take the set up out and about so I have brought another, smaller, lathe (Axi 14-16vs ) have the video set up above it and and ( to start with ) a monitor behind it. Now things start going wrong, every time I alter the speed on the lathe the monitor goes blank for a second or tw and then the picture comes back. The lathe, monitor, camera and a light are all plugged into an extension attached to the lathe stand. My first thought was the extension but then I noticed the monitor was going off for a second when I used the sharpener as well and that wasn't attached to the extension or even the same socket.

It was suggested that the monitor ( a cheap one ) was at fault so I got a good TV instead. Everything was fine for a few minutes then the TV started doing the same thing but a thousand times worse.

I am at a total loss.

Edit - just to make it clear, it is the picture going off, not the power supply to the TV

 

[Racers]

Sounds like interference, possibly your cables are picking up electrical noise from the motors, try to route them away from the motors or replace them.

Pete

 

[Grahamshed]

Hi Pete.
If that is all it is then it would be easy to deal with. It is true that the position of the extension sockets mean that ALL the cables run close to the lathe motor and the inverter box thingee......

But what about the TV picture going off when I use the sharpener which is four feet away in a different socket, the lathe is off if I am sharpening.

 

[Sheptonphil]

Have you tried a shielded cable for the monitor? Stops interference.

Phil

 

[Grahamshed]

never heard of that Phil. Where would I get one from.

Actually that raises a point that may or may not have any relevance. The tv over my big lathe is a proper cable from socket to TV. Both the monitor and the new TV are thin cable going to a box ( transformer ? ) and then proper cable from there to socket.

 

[Grahamshed]

I am narrowing this down
the tv works ok if the lathe is plugged in to the other side of the workshop ( different circuit )

A tv with a mains power supply works fine wherever the lathe is plugged in. It is only the TV and monitor with the box junction in the power supply that have a problem. What is that actually doing ? reducing to 12 volt ?

 

[sunnybob]

The lathe motor is causing the voltage to drop, The monitor dies because the input voltage is too low.

How big is the cable on the extension lead?

I have seen as low as a 150 volts on a 240 volt circuit because the cable was not rated for the load in use.

 

[Eric The Viking]

Wot Eee said!

It's interference of a sort. The real issue is your TV's internal power supply not being man enough for the voltage dips.

There is no easy solution. You might try looking for kit that would run from 12V (car battery), but that brings other problems if you derive the 12V from the mains (may not be very immune to RF interference).

The only solution at the moment (with the kit you have) is to run them from well-separated power supplies, which you're unlikely to find at a trade show. You might try running the video kit from a battery+inverter, but most inverters produce terribly wrong waveforms (should be a sine wave, but they're often triangular), and they introduce their own issues. From experience buying a better brand of TV won't necessarily help either.

Tricky problem.

E.

 

[WoodMangler]

How about running the monitor from a UPS ? That would take up the slack when the voltage drops temporarily (and would provide a certain amount of isolation from any rubbish on the mains).

 

[Grahamshed]

Interesting. I will look into that.

 

[LancsRick]

No possibility to get them running from different circuits?