GN Flatfield panel repair/mod

[Uranium235]

A few weeks ago I was out finishing off some RGB, but when I went to do the flat frames I could not understand why the GN panel wasnt working, the inverter wasnt making its usual high-pitched whining either.

On closer inspection of the panel I noticed that where the power cable enters the panel, it had become worn/frayed and therefore shorting out. Personally, I think this is a bit of bad design on something ive only used a handfull of times. And its not like ive been kicking it round the garden, Ive always put it straight back in the box it came in when im finished.

I think the power cable is so thin and weedy that it doesnt stand up to cold conditions very well (the plastic cable insulation becomes hard/brittle), so it wont take much flexing or tension to break it. For the sake of a couple of quid they could have mounted a power socket on it or used a heavier cable with a better casing (rubberised). Im probably not the only user of this type of panel who has exeprienced this problem.

Anyway, I plucked up the courage to take it apart last night and build a power coupling that will probably outlast the panel itself.

Bits needed:

Soldering iron + solder

Strong gaffer tape

HDD power cables (both male + female)

Cable strippers or a craft knife

Difficulty: Very easy

1) Here is the damage, not good for something so expensive.

2) Remove the black outer grippy-thing, dont worry it comes off and goes back on easily. I then stripped the ends of cables, and then tinned them with a bit of solder taking care to mark the +/- cables.

3) I then snipped away the unwanted cables from the HDD power socket & cables, stripped/tinned the ends. Then soldered female socket to the tinned wires in step 2, applied gaffer tape for insulation, then mounted the female connector on the back of the panel using some more gaffer tape. Finally, I soldered the the male HDD connector cables to the power cable coming from the inverter, insulated it - and its all set to go.

4) It's alive!!!!

[Sp@ce_d]

Nice one.. glad you fixed it .. they ain't cheap! I was a bit annoyed when I got mine to see no strain relief and the cables far too small for the weight of the free hanging in-line inverter. I tape the inverter to the panel but it's put me off buying another (larger) one.

For the effort required to fix what I regard as a sub standard design I think I'll have a go at making my own next time.. It's a shame, I wonder how many other users have had problems..?

[Uranium235]

I know of at least one other who has had the same problem (MikeWilson), his did exactly the same thing. I thought about emailing GN about it, but it depends on how widespread the problem is.

[RikM]

At work I use big LED light panels ocovered with a sheet of opal perspex (frosted white but they call it opal!) as a back light for checking for pinhole defects in films. The power inverter cables on those look exactly the same (weedy) design, so I'm not surprised it's broken. LED-Lightbox.com - Acyrlic LED light panels - Light Boxes - LED strips

I always imagined the GN panels would be circular rather than an illuminated square bit on a round board???

[Gina]

I'm going to try a disc of opal (frosted) Perspex attached to my scope and using daylight. I've used a sheet of paper on the scope and that seemed successful but needed taping on. So now I'm looking at a more durable solution.

[Stephen]

Gutted, glad it's sorted though!

On mine I have taped the cable to the rim of the panel, stops any undue wear being applied to the "joint."

I'm puzzled by one thing though, your panel is square? Mine is round. Did they change the design or something?

[Uranium235]

Gutted, glad it's sorted though!

On mine I have taped the cable to the rim of the panel, stops any undue wear being applied to the "joint."

I'm puzzled by one thing though, your panel is square? Mine is round. Did they change the design or something?

Thats what I assumed (it would be round) when I ordered it, what size did you get though? Mine was the 100mm version, which (just about) covers a 90mm frac. The pic on FLO clearly shows a round illuminated surface, so im not sure whether ive got an old or new version.

As long as its working im ok about it. Shame about the short, weedy cables you get with it though.

[Sp@ce_d]

Mine's square.. I was expecting round.. I got it 7 months ago. I queried it with Martin (FLO) at the time. It's the 100mm but really hardly covers the 80ED. I see FLO only seem to list the 100mm or 220mm now. I don't think the bigger ones worth the money to be honest.. not with the shoddy build quality.

[Stephen]

It could be the size. I got the 220mm directly from Gerd himself.

Was tempted to sell it and buy a smaller one now I've downsized to an ED80 : think I'll keep it if it's struggling with the ED80

[Uranium235]

Maybe I wouldnt go as far as using the word "shoddy", but I would say there is "substantial room for improvement". Im sure that sorting out a more robust way of delivering power isnt beyond the wit of GN

Ive just checked back over my receipts, and found that I'd had it barely 4 months before it went kaput.

[Uranium235]

It could be the size. I got the 220mm directly from Gerd himself.

Was tempted to sell it and buy a smaller one now I've downsized to an ED80 : think I'll keep it if it's struggling with the ED80

I reckon it would cover the ED80 with room to spare if you removed the dew shield - which would cause much hassle and be a PITA. When you place it on top of the dewshield, it gives you the impression that its a tight squeeze - but its actually ok. You just have to make sure its centered before you start taking flats. If I were you id stick with the big panel, it gives you more options.

Ive also used it to take flats with a 100mm frac but that was with with the 314L+, which wouldnt have been affected being as the chip is small.

[Gina]

A piece of printer/copier paper plus daylight is cheaper

[Uranium235]

A piece of printer/copier paper plus daylight is cheaper

I guess it depends on what youre trying to get rid of, if its vignetting or uneven illumination it might actually work - ive never tried it

But for dust bunnies, I cant see it being so effective becuase of the big difference in temperature (of the telescope) between the light and flat frames - it could be up to a 30 degree difference which may translate to a big difference in focus.

[yesyes]

Ive just checked back over my receipts, and found that I'd had it barely 4 months before it went kaput.

Shouldn't that be covered under warranty then?

[Gina]

I guess it depends on what youre trying to get rid of, if its vignetting or uneven illumination it might actually work - ive never tried it

But for dust bunnies, I cant see it being so effective becuase of the big difference in temperature (of the telescope) between the light and flat frames - it could be up to a 30 degree difference which may translate to a big difference in focus.

I've found it quite effective for dust bunnies Fixed the vignetting too

[Sp@ce_d]

The problem is it's not the right cable for a constantly flexing application. It's not robust enough and having the inverter swinging away in the middle of the cable with no support or strain relief is a joke really. These cables and the inverter are the type of components normally used internally where they are not swinging around!

[Uranium235]

Shouldn't that be covered under warranty then?

Maybe, and I think it was brought on the credit card too, so I would have been covered. My repair has probably voided that now, but if i'd gone down the claim route then I would have been without for a while. Its less hassle (and much quicker) just to fix it, as any potential replacement would have exactly the same design flaw.

[Gina]

Yes, it's often easier to fix it yourself than bother getting something replaced.

[Stephen]

A piece of printer/copier paper plus daylight is cheaper

Never managed to get the knack down just right ... EL panel gives perfect flats first time without messing

[Gina]

I have a disc of frosted Perspex (acrylic) on order as an upgrade to the paper

[RikM]

Never managed to get the knack down just right ... EL panel gives perfect flats first time without messing

I used to shoot sky flats with a bit of white T-shirt and elastic, it was okay but an EL panel is just so much more convenient to use and gives more consistent results.

[Gina]

I certainly agree that an EL panel would be a lot more convenient - but costs money. The size of the dew shield on the ED80 is about 115mm so 100mm isn't big enough. I might be prepared to pay £49 but £125 would buy me an Ha filter. No point in buying one that's too small - I would think this would produce a result like inverse vignetting when used for flats. The dew shield on my ED80 is not removable.

[Sp@ce_d]

I certainly agree that an EL panel would be a lot more convenient - but costs money. The size of the dew shield on the ED80 is about 115mm so 100mm isn't big enough. I might be prepared to pay £49 but £125 would buy me an Ha filter. No point in buying one that's too small - I would think this would produce a result like inverse vignetting when used for flats. The dew shield on my ED80 is not removable.

Its better than the "T shirt" method I used and it does work ok on the ED80 but as its a square illumination area the sides have to be very carefully aligned. Holding it in place is a pain. I've got a collection of elastic bands in use

For anything larger I'm going to investigate making my own as surely it can be made for less than the next step up of £125

[Gina]

I might make my own (number 1001 on the project list but I might move it up the list ) I already have a diffuser acrylic disc on order. If I want more diffusion I could add another of those discs or paper etc. I think for lighting a string of white LEDs would be suitable - I know some people have done this.

[garethmob]

i bought mine about 6 / 8 months ago, i bought the smallest one for my camera lens, i havent actually worked out how to power it yet, as its got werid clip things which i dont have anything to use