Need 12V F8T5 ballast

Thanks in advance.

Pretty simple circuit to build yourself, but off the shelf inverters are available for caravan/camper applications from people like Invertec. Ebay is a good source for a cheap Chinese inverter board.

JB

Is the scanner worth repairing? Lots of places throw those out fully working!

Lots of places throw them out when they get around to it.

On eBay they probably cost less than the shipping!

There are LED drop-in replecements that don't cost much more than an inverter ballast:

lamp? I

I like your attitude of not throwing anything away that may still be made to work. If you can't find a 'dead' one that has a working ballast, it should be possible to repair.

Used to design these. Contact me offline, if you want to tackle component level repair. Most likely the switching transistor. Designers tend to run these at the limits which is a timebomb for killing them.

PS: I have in storage [translate to NO ACCESS] 1 target printed in Switzerland by the people who print money that combined with software [you can write] that will automatically tell you a great deal about these mechanical scanners - focus across the field of view, illumination flatness, and jitter in the mechanical feed. The cost? Ten sheets at $300 per sheet.You can't believe the quality of the printing, let alone the the stability of the 'paper' that the image is on.

Plus, armed with a scope there are some simple things you can do to tweak the performance up to maximum.

That's a strange choice of lamp for a scanner. Scanners usually use cold cathode tubes (or LEDs nowadays).

Bare in mind that the lamp wearing out (electrode emission material all sputtered off) could stress the ballast and cause it to fail if not properly designed. So if you get a new ballast, might want to change the lamp too.

--
Andrew Gabriel 
[email address is not usable -- followup in the newsgroup]

I don't think he's talking about that kind of scanner.

On Sat, 12 Jan 2013 14:37:24 +0000 (UTC), snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) put together some random words that came up with:

fluorescent =

lamps.

The scanner is an old Hasselblad Imacon Precision II/III film scanner. The lamp is fixed, and the film moves around a drum as it is scanning. There is nothing out there that compares with the output of this scanner, and the new models are even better. There are a lot Precision IIs out there, and Hasselblad doesn't supply motherboards for these anymore. The lamps are standard Osram lamps, but the ballast for these is integrated on the motherboard. New models of this scanner sell for around $15K-$20K, so the older models are well worth saving. My question is for another person, as my scanner works fine, but eventually it will need to have electronics replaced. There is also some talk about replacing the entire motherboard with a modern micro board (like the Arduino), and having the lamps powered directly from an offline ballast.

It looks line the CCD is connected to the motherboard via a serial link, but I haven't done enough investigation to know that.

Steve

These guys have some, but the smallest one they list is for a single lamp of 15 to 22 W, bigger than the 8 W tube you have:

This place has them from a couple of different vendors, and they go down to the 8 W range you need:

Standard disclaimers apply; I don't get money or other consideration from any companies mentioned.

A couple of thoughts:

The built-in ballast may be running the lamp harder than an off-the- shelf ballast would to get more light, or maybe a little bit differently than an off-the-shelf inverter would to get a slightly different color from the lamp. (Other people here in sci.engr.lighting will know more about this second point than I do.) The test for this would be to scan the same photo on a working scanner and then on a scanner with the replacement ballast and see how well the colors match. Even if this happens, it might be possible to fix the color changes in software.

The built-in ballast may have some kind of status reporting back to the main microcontroller, such that the scanner will refuse to work if it thinks the lamp is not there. The test for this is maybe to remove the lamp from an otherwise working scanner and try to do a scan, maybe with a flashlight or some other light source where the original lamp was. If the scanner works but produces a dark or dim picture, then OK. If the scanner refuses to even start, you'll have to figure out how to fool it into thinking that the lamp is still there.

At the prices you cited, IMHO it's worth taking a little time to play with it to see if you can come up with a workable way to replace the built-in ballast.

Matt Roberds

Another thought - assuming the scanner uses light from one side of the tube, make up an LED replacement tube using a length of LED strip (or enough separate LEDs). It will be much easier to power this from 12V. The challenges will be getting the light sufficiently uniform (use lots of small LEDs rather than a few bigger ones, and a diffusing material), and the spectrum, but the spectrum from an F8T5 is likely to be rather grotty anyway, unless they are expensive special tubes.

Raspberry Pi has a TTL serial camera interface on it.

--
Andrew Gabriel 
[email address is not usable -- followup in the newsgroup]

If you just need one, buy a fluorescent lantern that runs on 12V and pirate it. For example, the Rayovac SP8DA Black Sportsman 8D Area Lantern runs on

8 D cells and has two 9W U shaped F9W-1 bulbs. Can run either one or both, so it should be happy with your 8 watt bulb, and has lots of good reviews for quality and longevity. Under $50 at amazon, I'm sure you can find it cheaper. Or Makita makes a 12V trouble light, and I'm sure many others do to, you might even find one that uses your f8t5 bulb.

On Sat, 12 Jan 2013 14:37:24 +0000 (UTC), snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) put together some random words that came up with:

The scanner is an old Hasselblad Imacon Precision II/III film scanner. The lamp is fixed, and the film moves around a drum as it is scanning. There is nothing out there that compares with the output of this scanner, and the new models are even better. There are a lot Precision IIs out there, and Hasselblad doesn't supply motherboards for these anymore. The lamps are standard Osram lamps, but the ballast for these is integrated on the motherboard. New models of this scanner sell for around $15K-$20K, so the older models are well worth saving. My question is for another person, as my scanner works fine, but eventually it will need to have electronics replaced. There is also some talk about replacing the entire motherboard with a modern micro board (like the Arduino), and having the lamps powered directly from an offline ballast.

It looks line the CCD is connected to the motherboard via a serial link, but I haven't done enough investigation to know that.

Steve