Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

DerbyBorn pretended :
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

No, with use they wear out and become dim.

Not really. The inside of the little cells gets blackened and sometimes the
cathode coating becomes inefficient. In one case where somebody tried to
increase it it started, presumably by some kind of static system to
illuminate some of the adjoining segments. that was a Casio clock radio with
a similar tube type display.
Worth a try, but be careful

I think the cassio one had about 100 v from a little inverter on it.
Brian

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"DerbyBorn" wrote in message
2.236...
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

The worst one I had was a Decimo Jumbo digital clock.
Of course it was not digital at all, it was basically a rotating sequencer
each contact lighting a neon behind the frosted segmaent on the front.
Eventually as the neon's got blackened the segments were all different
brightness's. I did take mine apart and replaced them and used a slightly
larger resistor to make them all a bit dimmer to save them, but eventually
the work needed and my reducing eyesight made it somewhat pointless to fix.
Talk about a daft design.
Brian

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"Harry Bloomfield" wrote in message
news
DerbyBorn pretended :
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

No, with use they wear out and become dim.

DerbyBorn wrote:
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

You might be able to increase the voltage VERY slightly on the heaters
but if you go too far, they will pop and the thing becomes useless.

A few extra turns on the transformer wired in series antiphase to the
PRIMARY will up the secondary voltage a little and increase the emission
of the heaters. It should also increase the anode-cathode voltage which
will also help.

If you have access to a variac then you can use that to experiment with
first to see if there is a useful effect.

On 07/07/18 10:57, DerbyBorn wrote:
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

If its fixitorchuckit this is what someone has reported

"The filament oxidizes which reduces the number of electrons that can be
emitted at the same drive current. Driving it with higher current
(constant current power supply is necessary) to white hot condition for
5-10 seconds will breathe new life into the display. It's unlikely that
the phosphors are damaged if the whole display is dim. You might find a
few "shapes" such as a leading zero or the decimal will be permanently
dimmed, but an overall rejuvenation will minimize brightness differences.

It's not a permanent solution, but it does give you a few years. I did
it to both of my bedside clocks and they've managed to look good for
almost four years of 24/7 operation."

--
The New Left are the people they warned you about.

On 07/07/18 11:31, Huge wrote:
On 2018-07-07, Bob Minchin wrote:
DerbyBorn wrote:
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

You might be able to increase the voltage VERY slightly on the heaters

Heaters?!?!? Do you imagine this thing has valves in it? Or are you just
taking the ****?

Oh dear

https://en.wikipedia.org/wiki/Vacuum...t_display#Fade

Poor old Huge. No wonder he is a remoaner. He might not be able to live
without an EU to wipe his botty.


--
€œA leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
€œWe did this ourselves.€�

ۥ Lao Tzu, Tao Te Ching

Bit like us humans then really!
Brian

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"Harry Bloomfield" wrote in message
news
DerbyBorn pretended :
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

No, with use they wear out and become dim.

In article 6,
DerbyBorn writes:
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

I've got one of those - probably 20 years old, although never needed
to look inside it as yet.

There's a brighness high/low switch on the back. Yours hasn't
got knocked to low, or stuck on low regardless of setting, has it?

Display is a vacuum fluorescent tube, and these do dim over time
due to the phosphor wearing out, and the cathode wire emission
coating reducing in efficiency. There are things that can be done
to improve brightness, lookup Vacuum fluorescent display rejuvenation.
Also, if not used for a long time, it may require a few days to return
to normal brightness.

Another problem could be the tube supply - they normally have a
separate supply due to requiring higher voltage than the radio
circuitry. You might find a smoothing capacitor has died and is
pulling the voltage down.

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

Yes well, there are so many ways these things work. I thought most were cold
cathode and the problem was jointly low emission from the cathode and Ion
poisoning of the phosphor itself. back in the old days of CRTs they used to
fire electron beams at the side of the tube then bend them back using a
magnet, but the ions being heavier, went straight out the side and hence did
not damage the phosphor as much long term.
Brian

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"Bob Minchin" wrote in message
news
DerbyBorn wrote:
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

You might be able to increase the voltage VERY slightly on the heaters but
if you go too far, they will pop and the thing becomes useless.

A few extra turns on the transformer wired in series antiphase to the
PRIMARY will up the secondary voltage a little and increase the emission
of the heaters. It should also increase the anode-cathode voltage which
will also help.

If you have access to a variac then you can use that to experiment with
first to see if there is a useful effect.

No its cold cathode if its like the Casio devices. Its still glass though
and has anodes and cathodes etc. its very like the cells in old Plasma TVS
on a smaller scale.
Brian

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"Huge" wrote in message
...
On 2018-07-07, Bob Minchin wrote:
DerbyBorn wrote:
Old but still working - analogue radio, The time display is not as
bright
as it was - green fuorescent. Can it be tweaked up a bit?

You might be able to increase the voltage VERY slightly on the heaters

Heaters?!?!? Do you imagine this thing has valves in it? Or are you just
taking the ****?

--
Today is Pungenday, the 42nd day of Confusion in the YOLD 3184
~ Stercus accidit ~

There are obviously at least two technologies here. Do we know which one
Sony used?

Either way pollution of the cathode was always an issue. Whether it was
oxide or not I can only guess, sounds like they have not been evacuated well
enough if it is.
Like I say some do have false segments lit if you up the volts. The burning
off of the cathode in the way you describe is the same system we used to
use in CRT rejuvenators back in the day, when overheating of the cathode
with special current limiting and some had inverted anode volts to, which
could for example get a tube to work for a couple of years more. Certainly
some colour tubes could get the guns rebalanced to within adjustment range
doing this. The question was, was it really cost effective when labour costs
started to climb.
Brian

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"The Natural Philosopher" wrote in message
news
On 07/07/18 10:57, DerbyBorn wrote:
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

If its fixitorchuckit this is what someone has reported

"The filament oxidizes which reduces the number of electrons that can be
emitted at the same drive current. Driving it with higher current
(constant current power supply is necessary) to white hot condition for
5-10 seconds will breathe new life into the display. It's unlikely that
the phosphors are damaged if the whole display is dim. You might find a
few "shapes" such as a leading zero or the decimal will be permanently
dimmed, but an overall rejuvenation will minimize brightness differences.

It's not a permanent solution, but it does give you a few years. I did it
to both of my bedside clocks and they've managed to look good for almost
four years of 24/7 operation."

--
The New Left are the people they warned you about.

On Saturday, 7 July 2018 10:57:39 UTC+1, DerbyBorn wrote:
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

If it's a VFD display, typically a light blue-green but sometimes other colours, there are several ways to improve output.
1. Raise anode voltage. They tend to get run around 30v, I've happily run them upto what was it, 150 or 180v I think. This is one of the easier fixes.
2. Increase filament voltage/current slightly.
Others have mentioned other approaches.

If it's another type of display, different story.


NT

On Sat, 7 Jul 2018 10:40:28 -0000 (UTC),
(Andrew Gabriel) wrote:

In article 6,
DerbyBorn writes:
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?

I've got one of those - probably 20 years old, although never needed
to look inside it as yet.

There's a brighness high/low switch on the back. Yours hasn't
got knocked to low, or stuck on low regardless of setting, has it?

Display is a vacuum fluorescent tube, and these do dim over time
due to the phosphor wearing out, and the cathode wire emission
coating reducing in efficiency. There are things that can be done
to improve brightness, lookup Vacuum fluorescent display rejuvenation.
Also, if not used for a long time, it may require a few days to return
to normal brightness.

Another problem could be the tube supply - they normally have a
separate supply due to requiring higher voltage than the radio
circuitry. You might find a smoothing capacitor has died and is
pulling the voltage down.

Mine must be slightly later. The min/max switch isn't a switch, it's
a button and it works in a circular fashion - each press makes it
brighter until, at maximum, the next press takes it to minimum and you
start again!

(Andrew Gabriel) wrote in
news
In article 6,
DerbyBorn writes:
Old but still working - analogue radio, The time display is not as
bright as it was - green fuorescent. Can it be tweaked up a bit?

I've got one of those - probably 20 years old, although never needed
to look inside it as yet.

There's a brighness high/low switch on the back. Yours hasn't
got knocked to low, or stuck on low regardless of setting, has it?

Display is a vacuum fluorescent tube, and these do dim over time
due to the phosphor wearing out, and the cathode wire emission
coating reducing in efficiency. There are things that can be done
to improve brightness, lookup Vacuum fluorescent display rejuvenation.
Also, if not used for a long time, it may require a few days to return
to normal brightness.

Another problem could be the tube supply - they normally have a
separate supply due to requiring higher voltage than the radio
circuitry. You might find a smoothing capacitor has died and is
pulling the voltage down.


Not seen a switch. More like 30 years old.

wrote in
:

On Saturday, 7 July 2018 10:57:39 UTC+1, DerbyBorn wrote:
Old but still working - analogue radio, The time display is not as
bright as it was - green fuorescent. Can it be tweaked up a bit?

If it's a VFD display, typically a light blue-green but sometimes
other colours, there are several ways to improve output. 1. Raise
anode voltage. They tend to get run around 30v, I've happily run them
upto what was it, 150 or 180v I think. This is one of the easier
fixes. 2. Increase filament voltage/current slightly.
Others have mentioned other approaches.

If it's another type of display, different story.


NT


The fixes are beyond me - any experience of ones that project onto the
ceiling?

In article ,
DerbyBorn writes:
(Andrew Gabriel) wrote in
news
In article 6,
DerbyBorn writes:
Old but still working - analogue radio, The time display is not as
bright as it was - green fuorescent. Can it be tweaked up a bit?

I've got one of those - probably 20 years old, although never needed
to look inside it as yet.

There's a brighness high/low switch on the back. Yours hasn't
got knocked to low, or stuck on low regardless of setting, has it?

Display is a vacuum fluorescent tube, and these do dim over time
due to the phosphor wearing out, and the cathode wire emission
coating reducing in efficiency. There are things that can be done
to improve brightness, lookup Vacuum fluorescent display rejuvenation.
Also, if not used for a long time, it may require a few days to return
to normal brightness.

Another problem could be the tube supply - they normally have a
separate supply due to requiring higher voltage than the radio
circuitry. You might find a smoothing capacitor has died and is
pulling the voltage down.


Not seen a switch. More like 30 years old.

Actually, mine must be older than 20 years - had it in my previous
place. Just inspected it for a date. Couldn't see one, but the
backup battery in it says use by Feb 98 (and still works), so
probably 25 years old.

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

In article 6,
DerbyBorn writes:
The fixes are beyond me - any experience of ones that project onto the
ceiling?

The very few I've seen are not very bright, and I doubt could
be read in my bedroom in the morning at this time of year.
Possibly not suitable if you are short sighted either.

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

Huge submitted this idea :
Heaters?!?!? Do you imagine this thing has valves in it? Or are you just
taking the ****?

They have heaters in, they are valves.

On Sunday, 8 July 2018 10:49:17 UTC+1, Harry Bloomfield wrote:
Huge submitted this idea :

Heaters?!?!? Do you imagine this thing has valves in it? Or are you just
taking the ****?

They have heaters in, they are valves.

funny how most people think valves have disappeared. VFDs & magnetrons are valve technology, and both are in widespread use in consumer appliances, and VFDs in cars.


NT

On 08/07/2018 10:49, Harry Bloomfield wrote:
Huge submitted this idea :
Heaters?!?!? Do you imagine this thing has valves in it? Or are you just
taking the ****?

They have heaters in, they are valves.

Actually VFDs have bare filaments, and 'heater' usually implies an
indirectly heated cathode.

--
Max Demian

On 07/07/2018 10:57, DerbyBorn wrote:
Old but still working - analogue radio, The time display is not as bright
as it was - green fuorescent. Can it be tweaked up a bit?


I have one that was 29 years old last May. Still going strong but you
can only read the display in the dark. However, everything else is
perfect still. It's woken me and the memsahib up for work ever since I
got a job that required me to keep fixed hours rather than working when
I wanted. I shall retire the clock when I retire. If it fails before
then I may consider that a signal I should retire.