Solution for low AC and clock lights ?

[asylum]

Dear All,

I did not find a real answer to this problem. My clock and AC/ventilation have a very low intensity. I think this is a matter of time that they become darker and darker. How can we get them brighter again ? Are there bulbs in the clock and AC modules ? Will new bulbs help recover a better intensity ? Or is this a lcd insoluble problem ?

 

[Heineken]

Some technical background:
Both the CCU (Climate Control Unit) and the clock (and the radio btw.) use Vacuum Fluorescent Displays (VFDs). They are fundamentally different from LCD and have no general backlight illumination bulbs.

Both modules have a dimming mode controlled by the illumination (lights) power supply line. When switching on the headlights they should both dimm down.
If they don't, they are either always on full brightness or fully dimmed. In case they are fully dimmed (which would explain your situation), the corresponding Illumination wire would be a first starting point.

 

[asylum]

The dimming mode is functional. The brightness switches from low to very low So is there a way to have these VFDs bright again ? Or we can just wait and see them get darker and darker ?

 

[Heineken]

Good to know that dimming works.

It's a bit unusual to have them dim that much over lifetime but I'm not aware of a way to make them brighter again, besides replacing, since it's simply wear of the phosphor coating.

 

[vf2ss]

Over at eevblog they say you can fix fatigued VFD's by flashing the filament temp with a higher voltage for a few seconds. In this thread the OP reported back a couple years later saying his VFD display was still running strong after being rejuvenated with this process. However, it seems like a temporary solution that will only give a few years and am curious, Heineken, what your thoughts and/or experience might be with this approach?

 

[Heineken]

I'm not an expert on vacuum tubes (that's what VFDs are) but general assumption is like stated above, a temporary measure.

For the radio there would be a way (not exactly simple) to overheat the filament but the clock or CCU hasn't been investigated in this regard.

 

[Old Guy]

Fade in VFDs is a known issue. If you look at the Wikipedia page on VFDs it has a short paragraph describing the problem. The color of the display (in particular the phosphors used) does affect lifetime and the red / orange displays are reported to have a shorter lifetime than the bluish displays.

If all of your VFD displays are getting consistently dim then it is probably just a case of them getting old. I can't comment on the rejuvenating trick. The descriptions of the technique leave out most of the details about how much filament voltage (or actually how much current) and for how long. You would need to figure out which pins are the filament pins and you might want to actually remove the display if you are going to try the 'filament flash' technique so that you don't cook something else. As I recall, the display in the head unit is from Noritake Itron and if you scrounge around on the web you may be able to find pinouts for the display. Last time I checked Noritake Itron was still in business. If you get the display part numbers perhaps you can find replacements. Prime member @drew was fiddling around with the display on the stereo head unit and may be able to advise on the display pin arrangements and replacement parts. Perhaps he figured out how to drive a different display?

If the display brightness problem is limited to just one device, make sure you don't have an electrolytic capacitor issue. A failing electrolytic capacitor in the power supply can result in problems with the filament voltages.

 

[Heineken]

The CCU is certainly special but I'm wondering if the Honda Prelude clock might have the same VFD display as the NSX clock?

 

[Heineken]

By the way, the orange display of the NSX is created (at least on the radio) by a filter on top of a bright blue/green display.

 

[vf2ss]

Yes, all 3 (clock, climate control, radio) are that way [LINK]

 

[asylum]

Both clock and ccu have the same brightness. I have an aftermarket radio. Well, it seems we have to live with that.

 

[Wild Turkey]

A lot of the clocks broke their installation clips so there are a bunch of clock guts out there - easy to swap. I have a set I'd let go cheap, but shipping to Europe would probably be a killer. Maybe post a WTB for some clock guts in Europe? Otherwise, a new clock is only $187 from amayama.

For the CCU display, sounds like @Heineken hasn't got any, but I wonder if it's worth reaching out to @Briank to see if he has any leftover displays from CCU's with caps burned beyond repair, as the CCU display is no longer available.

 

[Old Guy]

I have to admit that I have taken both the CCU and head unit apart and had never noticed the red/orange filter, perhaps because I wasn't doing anything with the displays. That said, putting a red / orange filter over a blue / green display is rather bizarre because a blue / green display won't generate much red / orange light so it automatically comes out pretty dim. I guess it does provide a work around for the short life span of the true red / orange phosphors. For asylum, if you have replaced the head unit and it has a blue / green display perhaps you just remove the filters on the clock and head unit to get matching display colors and a higher illumination level on the CCU and clock? You would have to figure out what to do with the instrument cluster if you want everything to match.

 

[drew]

The NSX instrument cluster can be converted to blue with the Accord lamp assembly. It appears to be a straight drop in for the NSX cluster.

I have a few laying around and I'll be on the States next month.

 

[vf2ss]

Do you recall what years Accord assembly is compatible?

 

[drew]

1993-1998 Honda Accords CD/CE/CF with the symmetrical four dial cluster.

I'm so old, I remember "getting the blues" was a thing

Sandy [aka lithiumus] did a fair amount of work on the cluster. He was a pioneer in this area.