Salvaging a VFD, where to start?

E

Eric Nielsen

Guest
A little background: I purchased a broken receiver/dvd player combo to use
the chassis as a computer case, and that worked rather well. However, I
would like to get the VFD from the original receiver running off the
computer, and I'm wondering how feasible this is. The VFD is custom
designed, I presume, but it would look better (and be cheaper) than buying a
VFD already built for PCs.

When I gutted the chassis, I kept everything intact and took photos along
the way, for future reference.

I need a few gaps in my knowledge filled in:

I have the circuit board with the front panel buttons, IR receiver, and VFD
intact. There are 4 connections for cables labelled as follows:

1) AC/AC/5V/GND/-30V/PWRSW/DVD
2) 5V/RXD/TXD/RTS/CTS/GND
3) MUTE/DGND/TUNER/ST/SD/PLCK/PLDI/PLDO/PLCE/RDSCK/RDSDA
4) NC/PCE/PDI/PCK/VDI/VCK/GND/MUTE/SCE/SDI/SCK

Connection (2) looks suspiciously like a serial port to me...which is why
I'm even bothering thinking about this. What would the "-30V" on connection
(1) be used for...the VFD? What are connections (3) and (4), potentially?

On the back of the cb, behind the VFD, there are 2 microchips, which I
assume comprise the VFD controller, so I'm not trying to operate a bare VFD.

How do I get started with this? I can build a cable to connect the PC
serial to connector (2), but would I swap Rx and Tx or not? What do I need
to power the VFD? Once powered and connected, can I fire up HyperTerminal
or whatever and just send random bytes to it and see what it does? Are the
control codes simple enough to figure out by trial+error?
 
"Eric Nielsen" <en@attbi.com> wrote in message news:<OQuTb.79084$U%5.424908@attbi_s03>...
A little background: I purchased a broken receiver/dvd player combo to use
the chassis as a computer case, and that worked rather well. However, I
would like to get the VFD from the original receiver running off the
computer, and I'm wondering how feasible this is. The VFD is custom
designed, I presume, but it would look better (and be cheaper) than buying a
VFD already built for PCs.

When I gutted the chassis, I kept everything intact and took photos along
the way, for future reference.

I need a few gaps in my knowledge filled in:

I have the circuit board with the front panel buttons, IR receiver, and VFD
intact. There are 4 connections for cables labelled as follows:

1) AC/AC/5V/GND/-30V/PWRSW/DVD
2) 5V/RXD/TXD/RTS/CTS/GND
3) MUTE/DGND/TUNER/ST/SD/PLCK/PLDI/PLDO/PLCE/RDSCK/RDSDA
4) NC/PCE/PDI/PCK/VDI/VCK/GND/MUTE/SCE/SDI/SCK

Hi Eric,
Click to expand...

1, looks like the AC for the filament voltages, the -30V for the
control grid & the other for GND and logic +5V.

2, I suspect like you, to be the data to control the display.

3&4, look to be output for the panel buttons

You need to post the IC numbers on the controllers for the VFD. I
strongly suspect it will be some embedded CPU with custom program. If
you are lucky they may have used some generic display serial protocol.

http://www.noritake-elec.com/vfdtech.htm

Regards
Wes.
 
"Eric Nielsen" <en@attbi.com> wrote in message
news:OQuTb.79084$U%5.424908@attbi_s03...
A little background: I purchased a broken receiver/dvd player combo to
use
the chassis as a computer case, and that worked rather well. However, I
would like to get the VFD from the original receiver running off the
computer, and I'm wondering how feasible this is. The VFD is custom
designed, I presume, but it would look better (and be cheaper) than
buying a
VFD already built for PCs.

When I gutted the chassis, I kept everything intact and took photos along
the way, for future reference.

I need a few gaps in my knowledge filled in:

I have the circuit board with the front panel buttons, IR receiver, and
VFD
intact. There are 4 connections for cables labelled as follows:

1) AC/AC/5V/GND/-30V/PWRSW/DVD
2) 5V/RXD/TXD/RTS/CTS/GND
3) MUTE/DGND/TUNER/ST/SD/PLCK/PLDI/PLDO/PLCE/RDSCK/RDSDA
4) NC/PCE/PDI/PCK/VDI/VCK/GND/MUTE/SCE/SDI/SCK

Connection (2) looks suspiciously like a serial port to me...
Click to expand...
You are probably right. However it might no use standard RS-232 signaling
levels (+/- 12 volts) but TTL levels instead, so be careful if you hook it
up to the serial port of the PC.

How do I get started with this? I can build a cable to connect the PC
serial to connector (2), but would I swap Rx and Tx or not? What do I
need
to power the VFD? Once powered and connected, can I fire up
HyperTerminal
or whatever and just send random bytes to it and see what it does? Are
the
control codes simple enough to figure out by trial+error?
Click to expand...
Probably not, try to find information about the display controller. If you
are lucky it is a generic type, if not ..well maybe the manufacturer is
willing to help (don't count on it).

--
Peter van Merkerk
peter.van.merkerk(at)dse.nl
 
"Wes." <spamthis@hayclan-oz.com> wrote in message
news:cbaeebae.0402030107.22c5751@posting.google.com...
"Eric Nielsen" <en@attbi.com> wrote in message
news:<OQuTb.79084$U%5.424908@attbi_s03>...
A little background: I purchased a broken receiver/dvd player combo to
use
the chassis as a computer case, and that worked rather well. However, I
would like to get the VFD from the original receiver running off the
computer, and I'm wondering how feasible this is. The VFD is custom
designed, I presume, but it would look better (and be cheaper) than
buying a
VFD already built for PCs.

When I gutted the chassis, I kept everything intact and took photos
along
the way, for future reference.

I need a few gaps in my knowledge filled in:

I have the circuit board with the front panel buttons, IR receiver, and
VFD
intact. There are 4 connections for cables labelled as follows:

1) AC/AC/5V/GND/-30V/PWRSW/DVD
2) 5V/RXD/TXD/RTS/CTS/GND
3) MUTE/DGND/TUNER/ST/SD/PLCK/PLDI/PLDO/PLCE/RDSCK/RDSDA
4) NC/PCE/PDI/PCK/VDI/VCK/GND/MUTE/SCE/SDI/SCK

Hi Eric,

1, looks like the AC for the filament voltages, the -30V for the
control grid & the other for GND and logic +5V.

2, I suspect like you, to be the data to control the display.

3&4, look to be output for the panel buttons

You need to post the IC numbers on the controllers for the VFD. I
strongly suspect it will be some embedded CPU with custom program. If
you are lucky they may have used some generic display serial protocol.

http://www.noritake-elec.com/vfdtech.htm

Regards
Wes.
Click to expand...
If it uses a custom driver I'd gut it and get one of the high voltage shift
registers from Supertex, they're good for driving VFD's and Nixie tubes, and
you can control them with any microcontroller, or bit bang from the PC's
parallel port, etc.
 
1, looks like the AC for the filament voltages, the -30V for the
control grid & the other for GND and logic +5V.
Click to expand...
There are 2 small (6x2mm cylinder, 10x6x3mm rectangle) solid metal
components I don't recognize near the VFD labelled 'X1' and 'X2'. Am I
right in guessing these are transformers for the filament voltage? How do I
find out what voltage is needed for the AC into the circuit board?

Also, what is the easiest way of getting the -30V for the control grid?

You need to post the IC numbers on the controllers for the VFD. I
strongly suspect it will be some embedded CPU with custom program. If
you are lucky they may have used some generic display serial protocol.
Click to expand...
NEC Japan/D780024GC513/0121FP007
NEC Japan/D16315GB/9944KP003

Regards
Wes.
Click to expand...
Thank you for your help,
Eric
 
If it uses a custom driver I'd gut it and get one of the high voltage
shift
registers from Supertex, they're good for driving VFD's and Nixie tubes,
and
you can control them with any microcontroller, or bit bang from the PC's
parallel port, etc.
Click to expand...
With my experience, building a new controller board would not be worthwhile
over buying a PC-ready VFD from Matrix Orbital or similar. My interest in
salvaging this VFD is because it has about 2 dozen small custom
graphics/lights above a 9 character alphanumeric like
"DVD","CD","MP3","VCD","TUNER","dts","DD", etc. For my application, this is
superior to even a graphic display of similar size.
 
"Eric Nielsen" <en@attbi.com> wrote in message
news:caTTb.174178$nt4.764437@attbi_s51...
If it uses a custom driver I'd gut it and get one of the high voltage
shift
registers from Supertex, they're good for driving VFD's and Nixie tubes,
and
you can control them with any microcontroller, or bit bang from the PC's
parallel port, etc.

With my experience, building a new controller board would not be
worthwhile
over buying a PC-ready VFD from Matrix Orbital or similar. My interest in
salvaging this VFD is because it has about 2 dozen small custom
graphics/lights above a 9 character alphanumeric like
"DVD","CD","MP3","VCD","TUNER","dts","DD", etc. For my application, this
is
superior to even a graphic display of similar size.
Click to expand...
I would think a custom controller would be trivial, it's just a matter of
connecting each segment to the driver chip, certainly easier than trying to
drive an existing controller.
 
I would think a custom controller would be trivial, it's just a matter of
connecting each segment to the driver chip, certainly easier than trying
to
drive an existing controller.
Click to expand...
Hmm, I guess I don't know what you are describing then.
 
"Peter van Merkerk" <merkerk@deadspam.com> wrote in message news:<bvnq6f$tk387$1@ID-133164.news.uni-berlin.de>...
"Eric Nielsen" <en@attbi.com> wrote in message
news:OQuTb.79084$U%5.424908@attbi_s03...
A little background: I purchased a broken receiver/dvd player combo to
use
the chassis as a computer case, and that worked rather well. However, I
would like to get the VFD from the original receiver running off the
computer, and I'm wondering how feasible this is. The VFD is custom
designed, I presume, but it would look better (and be cheaper) than
buying a
VFD already built for PCs.

When I gutted the chassis, I kept everything intact and took photos along
the way, for future reference.

I need a few gaps in my knowledge filled in:

I have the circuit board with the front panel buttons, IR receiver, and
VFD
intact. There are 4 connections for cables labelled as follows:

1) AC/AC/5V/GND/-30V/PWRSW/DVD
2) 5V/RXD/TXD/RTS/CTS/GND
3) MUTE/DGND/TUNER/ST/SD/PLCK/PLDI/PLDO/PLCE/RDSCK/RDSDA
4) NC/PCE/PDI/PCK/VDI/VCK/GND/MUTE/SCE/SDI/SCK

Connection (2) looks suspiciously like a serial port to me...

You are probably right. However it might no use standard RS-232 signaling
levels (+/- 12 volts) but TTL levels instead, so be careful if you hook it
up to the serial port of the PC.

How do I get started with this? I can build a cable to connect the PC
serial to connector (2), but would I swap Rx and Tx or not? What do I
need
to power the VFD? Once powered and connected, can I fire up
HyperTerminal
or whatever and just send random bytes to it and see what it does? Are
the
control codes simple enough to figure out by trial+error?

Probably not, try to find information about the display controller. If you
are lucky it is a generic type, if not ..well maybe the manufacturer is
willing to help (don't count on it).
Click to expand...
What is VFD? I think of VFD as variable frequency drive, for
industrial strength motors, not consumer electronics.

H. R. (Bob) Hofmann
 
"Eric Nielsen" <en@attbi.com> wrote in message news:<p1STb.174105$nt4.764834@attbi_s51>...
1, looks like the AC for the filament voltages, the -30V for the
control grid & the other for GND and logic +5V.

There are 2 small (6x2mm cylinder, 10x6x3mm rectangle) solid metal
components I don't recognize near the VFD labelled 'X1' and 'X2'. Am I
right in guessing these are transformers for the filament voltage? How do I
find out what voltage is needed for the AC into the circuit board?

Also, what is the easiest way of getting the -30V for the control grid?

You need to post the IC numbers on the controllers for the VFD. I
strongly suspect it will be some embedded CPU with custom program. If
you are lucky they may have used some generic display serial protocol.

NEC Japan/D780024GC513/0121FP007
NEC Japan/D16315GB/9944KP003

Regards
Wes.

Thank you for your help,
Eric
Hi Eric
Click to expand...

If you have a read of the web page I gave (as below) you can get some
idea the way the AC voltages are needed for the filaments and why the
-30vdc. If you still have most of the guts you can have a look at the
power supply and see what the AC voltage are and how center-tap to GND
for offset is set up.
http://www.noritake-elec.com/vfdtech.htm

For the two ICs you listed

NEC upD16315 is found at the following URL and is the VFD Driver IC
(with Switch Matrix input), get the data sheet and have a good read.
http://www.necel.com/cgi-bin/nesdis/o003_e.cgi?article=UPD16315

NEC upD780024GC could be similar to upD780024AGC and can be found at
the URL below. This probably contains the custom program that
interfaces the above Driver IC with the rest of the system you striped
http://www.necel.com/cgi-bin/nesdis/o003_e.cgi?article=UPD780024A

You need to trace out the panels PCB connections to see how the
manufacture has interfaced these two IC into their display system and
then look at what point you can break into it and write some PC code
to interface and drive the VFD, possibly even read back the switches
if they are wired into the VFD Driver IC. (all at TTL levels :^)

Regards
Wes.
 
What is VFD? I think of VFD as variable frequency drive, for
industrial strength motors, not consumer electronics.

H. R. (Bob) Hofmann
Click to expand...
Vacuum Fluorescent Display, do a google search for more info, used on most
consumer electronics now. Used to be common on calculators back in the 70's.
 
"James Sweet" <jamessweet@hotmail.com> wrote in message news:<I41Ub.217395$xy6.1129087@attbi_s02>...
What is VFD? I think of VFD as variable frequency drive, for
industrial strength motors, not consumer electronics.

H. R. (Bob) Hofmann

Vacuum Fluorescent Display, do a google search for more info, used on most
consumer electronics now. Used to be common on calculators back in the 70's.
Click to expand...
OK - I understand fully.

Bob Hofmann
 
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