muckypup
New member
Anyone tell me where to start looking for problems with my Koden radar? It seems to start up ok, warms up and the display shows ok, but all I seem to get is random dots... It worked ok a month ago!
S.
S.
Radar troubles
- Thread starter muckypup
- Start date
G
Guest
Guest
What exactly happened in that month? Most failures can be attributed to outside events.
Do you get random dots whatever the gain setting? Does it only occur on high gain?
Are they a few noise dots or nearly all the pixels switching?
What difference do you get with different ranges?
Have you broken the video connection at the mast base? This is the tiny coax?
Has it been set for manual tuning?
Do you get random dots whatever the gain setting? Does it only occur on high gain?
Are they a few noise dots or nearly all the pixels switching?
What difference do you get with different ranges?
Have you broken the video connection at the mast base? This is the tiny coax?
Has it been set for manual tuning?
muckypup
New member
[ QUOTE ]
What exactly happened in that month? Most failures can be attributed to outside events.
[/ QUOTE ]
Boat was moved from Swansea to Burnham on the back of a lorry! /forums/images/graemlins/smile.gif
[ QUOTE ]
Do you get random dots whatever the gain setting? Does it only occur on high gain?
[/ QUOTE ]
The higer the gain, the more more dots.
[ QUOTE ]
Are they a few noise dots or nearly all the pixels switching?
[/ QUOTE ]
Thinking about this, they are probably just noise dots.. there isn't a great concentration of them.
[ QUOTE ]
What difference do you get with different ranges?
[/ QUOTE ]
Same on the display
[ QUOTE ]
Have you broken the video connection at the mast base? This is the tiny coax?
[/ QUOTE ]
I visually checked the connections and they all looked ok, however the radar arch was lowered for the move. I wonder if the wire could have broken inside the cable?
[ QUOTE ]
Has it been set for manual tuning?
[/ QUOTE ]
Yes - it's so old that it's only manual!
Steve
What exactly happened in that month? Most failures can be attributed to outside events.
[/ QUOTE ]
Boat was moved from Swansea to Burnham on the back of a lorry! /forums/images/graemlins/smile.gif
[ QUOTE ]
Do you get random dots whatever the gain setting? Does it only occur on high gain?
[/ QUOTE ]
The higer the gain, the more more dots.
[ QUOTE ]
Are they a few noise dots or nearly all the pixels switching?
[/ QUOTE ]
Thinking about this, they are probably just noise dots.. there isn't a great concentration of them.
[ QUOTE ]
What difference do you get with different ranges?
[/ QUOTE ]
Same on the display
[ QUOTE ]
Have you broken the video connection at the mast base? This is the tiny coax?
[/ QUOTE ]
I visually checked the connections and they all looked ok, however the radar arch was lowered for the move. I wonder if the wire could have broken inside the cable?
[ QUOTE ]
Has it been set for manual tuning?
[/ QUOTE ]
Yes - it's so old that it's only manual!
Steve
G
Guest
Guest
Bets are on the cable. Video coax inner.
Second the arch had a bang. Take the lid off and see if it looks normal inside.
Uneventful month!
Second the arch had a bang. Take the lid off and see if it looks normal inside.
Uneventful month!
MarkJohnson12345
New member
Do you know for certain that the antenna is turning??
On my Furuno, the drive belt came off. The screen showed the sweep, but in fact it was not moving.
The software should detect a non movement. But in my case the antenna had stopped over the switch that detects this.
anyway, once the belt was on it worked fine.
My belt came off when ashore, in high winds early this year. I suspect that the fact the boat was on the hard, without the cushion of water, allowed vibrations up the mast to dislodge the belt.
Worth a look anyway.
Best of luck
Mj
On my Furuno, the drive belt came off. The screen showed the sweep, but in fact it was not moving.
The software should detect a non movement. But in my case the antenna had stopped over the switch that detects this.
anyway, once the belt was on it worked fine.
My belt came off when ashore, in high winds early this year. I suspect that the fact the boat was on the hard, without the cushion of water, allowed vibrations up the mast to dislodge the belt.
Worth a look anyway.
Best of luck
Mj
muckypup
New member
I checked all of the cables to the radar today. Everything seems fine. I also popped the top off the radome, and fired it up and it seems to rotate fine. A visual inspection of the radome showed it very clean inside and nothing looking out of place.
I got the manual out and ran through the setting up procedure. This is the only result I could get.
I'm assuming that the dots are simply noise, so I used the controls to remove the noise. This is the best I could get.
Nothing on the radar, but random lines - some short, some long radiating from the centre of the display. They appear randomly and are erased in the next sweep.
Anyone recognise the problem?
Thanks
Steve
I got the manual out and ran through the setting up procedure. This is the only result I could get.
I'm assuming that the dots are simply noise, so I used the controls to remove the noise. This is the best I could get.
Nothing on the radar, but random lines - some short, some long radiating from the centre of the display. They appear randomly and are erased in the next sweep.
Anyone recognise the problem?
Thanks
Steve
MarkJohnson12345
New member
On the face of it the first picture would seem to suggest just a gain tweak is required.
The second picture showing lines is something that I do get occaisonally, for no obvious reason, just put it down to electronics.
But you have no radar image at all on the screen, were you out to sea when you took the photos, or just playing a Des O'Connor tape??
Too much gain will clear the screen as you know. Not an expert at Radars, but aparantly the Magnitron (what ever that is) does wear out or become too weak to be usable, and may need replacing if the set is old.
Aparantly they have a lifespan of X hours and will eventually need replacing.
Not much help I am afraid.
Good luck.
Mj
The second picture showing lines is something that I do get occaisonally, for no obvious reason, just put it down to electronics.
But you have no radar image at all on the screen, were you out to sea when you took the photos, or just playing a Des O'Connor tape??
Too much gain will clear the screen as you know. Not an expert at Radars, but aparantly the Magnitron (what ever that is) does wear out or become too weak to be usable, and may need replacing if the set is old.
Aparantly they have a lifespan of X hours and will eventually need replacing.
Not much help I am afraid.
Good luck.
Mj
muckypup
New member
Nope. The pic were taken in the marina and should show plenty of stuff.
.. and definately no Des O'Conner, although I'm not sure how that affects a radar /forums/images/graemlins/confused.gif
S.
.. and definately no Des O'Conner, although I'm not sure how that affects a radar /forums/images/graemlins/confused.gif
S.
MarkJohnson12345
New member
We played a Des O'Conor CD in the Scillies a few years ago, and it cleared the anchorage of most boats......
Excellent CD actually.
Mj
Excellent CD actually.
Mj
ShipsWoofy
New member
[ QUOTE ]
I checked all of the cables to the radar today. Everything seems fine.
[/ QUOTE ]
What did you check? How?
This looks like a video fault, as suggested already, I would be looking at the video cable connections / condition.
I would not be thinking gain right now, look at the evidence, it worked, it was disconnected and the arch moved, yet it is decided that the gain has gone tits-up, no logic here at all.
I checked all of the cables to the radar today. Everything seems fine.
[/ QUOTE ]
What did you check? How?
This looks like a video fault, as suggested already, I would be looking at the video cable connections / condition.
I would not be thinking gain right now, look at the evidence, it worked, it was disconnected and the arch moved, yet it is decided that the gain has gone tits-up, no logic here at all.
hightech
New member
Looks like your Magnetron has died, all you are seeing is backgound noise when you turn the gain up high.
Need an engineer to check and repair for you.
Fixed many like this over the years.
Need an engineer to check and repair for you.
Fixed many like this over the years.
muckypup
New member
I visually checked that all the connections.
The radar wasn't disconnected, the arch simply folds down and there is enough loop on the wires where they come out of the roof and are tied to the arch so nothing needs disconnecting.
I'm not sure how to check a radar cable.. You called it a video cable, I take it that the radome itself does most of the processing and sends a simple video signal to the display?
S.
The radar wasn't disconnected, the arch simply folds down and there is enough loop on the wires where they come out of the roof and are tied to the arch so nothing needs disconnecting.
I'm not sure how to check a radar cable.. You called it a video cable, I take it that the radome itself does most of the processing and sends a simple video signal to the display?
S.
ShipsWoofy
New member
From all the yacht sets I have seen the transmitter is in the dome, so all the high power stuff goes on up there. Otherwise you would need waveguide going up the mast.
I have a concern for you from you latest description, it is possible that there was water in the bottom of the dome case and tipping it onto it's side may have soaked the tx. Lets hope not.
The video cable is a light coax buried into the main cable, it is very weak and if like raymarine, the cable is all pretty cheap and nasty. Did you unplug and plug in the socket at the dome? Re-seating may just work, even with some loose, the cable is still going to move a bit and possibly dislodge.
Also have a good look at the bend, at the bottom of the arch, has it kinked, moved etc. Give it a shake when running, see if it makes a difference to the picture. If the picture goes mad, it either means something is loose or the cable is dead.
It could, might, be the magnetron, but my personal experience is that noise is usually a cable in the receive side. I would expect a dead magnetron to fail the pre-warm up cycle. Though, when trying to work out what was wrong with another RADAR which had stopped over the sensor I fought tooth and nail to say it could not be the scanner.
Always chase what you have disturbed first though. Rule 1.
I have a concern for you from you latest description, it is possible that there was water in the bottom of the dome case and tipping it onto it's side may have soaked the tx. Lets hope not.
The video cable is a light coax buried into the main cable, it is very weak and if like raymarine, the cable is all pretty cheap and nasty. Did you unplug and plug in the socket at the dome? Re-seating may just work, even with some loose, the cable is still going to move a bit and possibly dislodge.
Also have a good look at the bend, at the bottom of the arch, has it kinked, moved etc. Give it a shake when running, see if it makes a difference to the picture. If the picture goes mad, it either means something is loose or the cable is dead.
It could, might, be the magnetron, but my personal experience is that noise is usually a cable in the receive side. I would expect a dead magnetron to fail the pre-warm up cycle. Though, when trying to work out what was wrong with another RADAR which had stopped over the sensor I fought tooth and nail to say it could not be the scanner.
Always chase what you have disturbed first though. Rule 1.
ShipsWoofy
New member
Have you tried retuning it?
It should tell you how in the manual..
It should tell you how in the manual..
muckypup
New member
Nope... nothing was unplugged. The inside of the Radome looked immaculate and clean. If there had been water in I would have thought that there might have been some corrosion.
I like the idea of cable wobbling, I hadn't though of that. I will try this when I'm next down the boat & get SWMBO to watch the display.
I havn't tried retuning it. I have seen something about that in the manual and it means dismantling the display and fiddling with lots of tiny pots on the circuit board. I will have to leave myself a couple of hours to play with those carefully.
S.
I like the idea of cable wobbling, I hadn't though of that. I will try this when I'm next down the boat & get SWMBO to watch the display.
I havn't tried retuning it. I have seen something about that in the manual and it means dismantling the display and fiddling with lots of tiny pots on the circuit board. I will have to leave myself a couple of hours to play with those carefully.
S.