Discussion:
Need 12V F8T5 ballast
(too old to reply)
Steve
2013-01-11 03:13:07 UTC
Permalink
Raw Message
Does anyone know where I could find a 12V ballast for a F8T5 fluorescent lamp? I
have a scanner where the main board has quit powering one of the lamps.

Thanks in advance.

Steve
JB
2013-01-11 08:26:13 UTC
Permalink
Raw Message
"Steve" <***@nowhere.org> wrote in message news:***@4ax.com...
Does anyone know where I could find a 12V ballast for a F8T5 fluorescent
lamp? I
have a scanner where the main board has quit powering one of the lamps.

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
Greegor
2013-01-11 08:34:00 UTC
Permalink
Raw Message
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!
Robert Macy
2013-01-12 14:27:02 UTC
Permalink
Raw Message
Post by Steve
Does anyone know where I could find a 12V ballast for a F8T5 fluorescent lamp? I
have a scanner where the main board has quit powering one of the lamps.
Thanks in advance.
Steve
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.
Andrew Gabriel
2013-01-12 14:37:24 UTC
Permalink
Raw Message
Does anyone know where I could find a 12V ballast for a F8T5 fluorescent =
lamp? I
have a scanner where the main board has quit powering one of the lamps.
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]
Steve
2013-01-12 21:36:15 UTC
Permalink
Raw Message
Post by Andrew Gabriel
Does anyone know where I could find a 12V ballast for a F8T5 fluorescent =
lamp? I
have a scanner where the main board has quit powering one of the lamps.
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.
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
Andrew Gabriel
2013-01-13 11:56:22 UTC
Permalink
Raw Message
Post by Andrew Gabriel
Post by Steve
Does anyone know where I could find a 12V ballast for a F8T5
fluorescent =3D
Post by Andrew Gabriel
Post by Steve
lamp? I
have a scanner where the main board has quit powering one of the
lamps.
Post by Andrew Gabriel
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.
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.
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.
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.
Raspberry Pi has a TTL serial camera interface on it.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Carl Ijames
2013-01-13 17:17:44 UTC
Permalink
Raw Message
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.

-----
Regards,
Carl Ijames
"Steve" wrote in message news:***@4ax.com...

On Sat, 12 Jan 2013 14:37:24 +0000 (UTC), ***@cucumber.demon.co.uk
(Andrew
Post by Andrew Gabriel
Does anyone know where I could find a 12V ballast for a F8T5 fluorescent =
lamp? I
have a scanner where the main board has quit powering one of the lamps.
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.
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

m***@att.net
2013-01-13 05:08:13 UTC
Permalink
Raw Message
Followups set to sci.engr.lighting.
Post by Steve
Does anyone know where I could find a 12V ballast for a F8T5
fluorescent lamp?
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:
http://www.powerstream.com/ballast-1.htm

This place has them from a couple of different vendors, and they go
down to the 8 W range you need:
http://www.solarseller.com/12___24_volt_low_voltage_dc_fluorescent_ballasts__lit__light_it_technologies.htm

Standard disclaimers apply; I don't get money or other consideration
from any companies mentioned.
Post by Steve
I have a scanner where the main board has quit powering one of the
lamps.
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
Loading...