W5 head with some segments brighter than others

[ny1a]

I just purchased a 110 watt VHF Astro Spectra with a W5 head. Some of the segments in the LED display are brighter than others. The same segments are always the dim or bright ones. I am aware of the time-bomb capacitor problem causing displays to get dim altogether, but I have seen no discussion of the situation where just certain segments are apparently dim or bad. It is hard to see how this could be cause by either of those capacitors. My guess is that the display itself is simply bad. Does anyone have any insight into this issue? The head and radio were made in 1997, if that is relevant.

Thanks in advance for any wisdom you can give me.

David, NY1A

[Mike B]

The alphanumeric displays are not LEDs. They are vacuum florescent displays. Like the vacuum tubes of the past (mostly) the display segments slowly burn out over time with extended use. Each display segment is connected to a controller chip that also could have problems, although this is not usually the case.

Usually the vacuum florescent display need to be replaced to restore full brightness.

[GlennD]

I have found missing segments are usually corroded foil traces. Some dim segments are usually caused by a bad driver IC. If you look at the segment signals with a scope they should be nice flat square waves. Any tilt signifies a bad chip.

Also check the chip high voltage input for ripple. The very first thing I do to the head is replace the two 10Mfd 50V electrolitics.