Hayes Chronograph Display Repair

(This was originally a Twitter thread from January 24, 2022.)

January 24, 2022

Many of you know that I have an affinity for the Hayes Chronograph. I have several of them, I made a WiFi controller to set the time automatically, and I’ve repaired several of them. Here’s another page in the repair chapter.

The Hayes Chronograph uses a beautiful Futaba 6-LT-23 vacuum fluorescent display (VFD) that has a lovely cyan blue tint. Over time, the displays will fade in brightness and possibly stop lighting at all (I’ve yet to see the later).

Another vulnerability is the vacuum itself. During manufacture, a vacuum is applied from the back and sealed leaving a small glass nib that sticks out, just asking to be lightly tapped and broken. No vacuum, no display. One Chronograph I have suffers from this.

Long out of production, replacement displays are whatever are left lying around a warehouse. For years, I’ve looked and found many dead ends until I found some for sale overseas. I hesitated for a couple of years (!) before finally buying them. The process was more complex than it needed to be and I paid a premium for them.

The NOS VFDs I ordered arrived today. The sealed box rattled like wind chimes. And well, it wasn’t a pretty sight. Inside, there was carnage. Immediately I could see several seals broken and one outright cracked from the front. I don’t think these can repaired but tell me I’m wrong!

Some displays did survive. After straightening the 31 gnarly pins, I set about repairing the Chronograph with a bad display. Unsoldered 31 pins of the old display and soldered in the new one.

First power on: nothing. Puzzled, I checked for power. Nothing. Duh, no fuse! Added a fuse, tried again. The display lights up, but indecipherable? What time is it?

As I was trying to figure out what to do next, the display glitched lightly, and suddenly displayed the correct date and time! Yay for unexplained phenomena! This new Chronograph display is sooo bright!

I still chuckle at the sticker on top of this one. UN-REPAIRABLE.

Do you have a Hayes Chronograph? Let me know in the comments how your display is doing.

2 thoughts on “Hayes Chronograph Display Repair

  1. Permalink  ⋅ Reply

    Paolo Palazzi

    May 13, 2023 at 10:41am

    I have a Hayes Chronograph, which started to be used in 1986 (as the clock
    source for a Cray X-MP/48, “sn223”), then was decommissioned in 1990 (when sn223
    was decommissioned) and put back in operation as the clock on my work desk in
    When replacing the transformer, I could pick the exact secondary voltage to be
    as low as possible (ripple on C4 setting the lower limit), in order to keep it
    dim and have it last as long as possible.
    It is still working, but indeed some segments have uneven brightness and the
    overall brightness is barely acceptable when the room is in full sunlight.
    But I cannot replace the Chronograph with a more modern clock: I simply love it

  2. Permalink  ⋅ Reply


    August 16, 2023 at 3:27pm

    Hello, nice job with the chronograph!
    I’m in the need of 2-3 pieces of the same VFD. Did you find a good source for them?
    They are used in a tape recorder.

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