Vacuum Fluorescent Displays - How They Work & Can They Be Fixed?

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I received a Yamaha MT8XII from Adrian James form the channel we happy few music for servicing, and somewhere in its journey from the south to the north ends of the British mainland the Vacuum Fluorescent Display stopped working.
I've had smaller displays die on me before, but usually there was something very obviously wrong with the glass exterior - a bit broken off, a crack, etc. But this wasn't the case here. So I learned a bit about how these contraptions work, and other modes of failure.
The conclusion I've come to is that if the glass breaks, spoiling the vacuum, you're stuffed. If on the other hand the glass is in tact but the VFD just isn't lighting up, you might be able to recover it .
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CHAPTERS
0:00 Introduction
1:00 Anatomy of a VFD diagram & disclaimer
2:00 Glass case & acuum extraction port
2:40 Three internal layers of a VFD
3:28 How the VFD works
5:20 Pin layout
6:10 Establishing the health of VFD filaments
7:10 VFD counter on a Tascam 244
9:03 VFD display on a Tascam 424 Mk II
10:59 broken pins on the MT8xII's VFD display
13:04 soldering problems
15:40 Protecting a weak solder joint with 2 part glue

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Опубликовано:

3 июл 2024

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Комментарии : 13

@dragosistrate5623 2 месяца назад

Well done, sir! Very much appreciated your explanations and quality of video & audio. Thank you :)

@jamescross2229 26 дней назад

Hi from NZ. Thanks so much for the explanation. That was really good. I'm trying to troubleshoot a blank vfd on a late 90s kenwood car radio.

@nohrtillman8734 9 месяцев назад

Yikes! Finally got around to watching this from my list. Difficult to see exactly what you were dealing with since those pins are pretty tiny. But I can envision the super tiny cross-section you had left! Only other thing I can think of would be flux the cross section and pin. Pre-solder what’s left of the pin. Then hold it up against the display and touch the iron to it to just get it to flow. Almost a SMD tick technique. As long as it mechanically stays put, i don’t think those carry much power, so should hold. Great work!

@BadChizzle 11 месяцев назад

Hello! I’d like to request some more on the Yamaha MT4X, as I bought two units to better have a chance of combining parts if needed to come up with one fully functioning unit. I got lucky and the first one I received looks to be working fine… but as much knowledge as I can get on them will still be helpful. So… a Pinch roller and belt replacement, plus your take on demagnetizing said recorder… and anything else pertinent you might have learned and like to add, after fiddling around with yours, would be appreciated. Anyway… regardless of weather you do this or not, thanks for your help with the breakdown of the MT4X in the video you did on it! -Chuk

@Tetrakan 11 месяцев назад

Hey Chuk. I actually made a 15 min video on the MT4X for patreon. It's mostly about fitting tascam faders and motors where yamaha parts are unavailable. I see from another comment you build tube amps? I've got some questions about that subject, so maybe if you send me a private message over instagram or Facebook we could do an info swap?

@DantePettus 4 месяца назад

How can you determine the power output of the pins? I have a Roland S-550 Digital Sampler. It used a VFD. Yet I cannot find a replacement screen fro it. I wish to replace it with one of these newer LED or OLED screens. But the pinout is never listed in any of Roland's product that use the same screen. Thank you for your help!!

@matiascid1307 6 месяцев назад

Hello, silly question, is it possible for a VFD to be damaged by a fall to the ground? Are they fragile devices? Thanks in advance

@Tetrakan 6 месяцев назад

Yes. They are made of glass, and contain a vacuum, so a full could cause a crack, allow air to enter, then it will no longer work.

@Dancopymus 3 месяца назад

Greetings Tetrakan. I would like your help. I have a VFD, taken from a Video Cassette and it was working but, after a while, I went to do a test to check the VFD pinout and, putting 3V + GND on the Filaments and around 12V on the Anodes, the same didn't light up. After watching your video, I became interested in looking into the VFD and discovered that the nozzle for removing air from the glass tube (vacuum) had a small hole at the tip. So, I ask you the question: is it possible to recover the VFD, using some type of glue to cover the small hole or, in some way, remove the air from the glass tube? And if so, what way would you advise me? My thanks and I look forward to your response.

@Tetrakan 3 месяца назад

I’m sorry, your guess is as good as mine…if you find a solution please report back here

@BadChizzle 11 месяцев назад

You did thoroughly confuse me with this display tube explanation. Ha! Aaaaaand… I can build tube amps from scratch. 😂🤣 These things are crazy!! If you start talking multiplexing, my eyes cross and I begin to become dizzy. 😳

@Tetrakan 11 месяцев назад

Ha! I love Uncle Doug's channel, so I've got a fair idea of how tube amps work, but the point-to-point wiring and lethal voltages are way, way outside my comfort zone! This is a pity because I have a little tube amp I bought in the mid 90s as a teenager from a boutique UK builder who is out of business. It's probably not far off a Fender Champ to someone who works on these things often, but it looks nearly unintelligible to me!