I bought a Index 645 that has a Baldwin DRO on it. This is
an old style with nixie tubes. The DRO has an independent
box for each the X and Y axis. The X axis worked fine, the
Y would not power up. I took it apart and fixed the power
supply to the nixie tubes and then it came on although one of
the nixies is burned out. Unfortunately there is some problem
in the logic chips I assume as the "zero" and "set" buttons do
not work correctly. Is anyone here experienced in fixing these
type of units or know where to get schematics?

jabba wrote:
I bought a Index 645 that has a Baldwin DRO on it. This is
an old style with nixie tubes. The DRO has an independent
box for each the X and Y axis. The X axis worked fine, the
Y would not power up. I took it apart and fixed the power
supply to the nixie tubes and then it came on although one of
the nixies is burned out. Unfortunately there is some problem
in the logic chips I assume as the "zero" and "set" buttons do
not work correctly. Is anyone here experienced in fixing these
type of units or know where to get schematics?

Curious here, are the nixies the only tubes present? Some tubes were actually
designed as logic devices and in fact the burned-out nixie could theoretically
affect the device operation. Not that it should have been designed that way
though.

you may find that you can sell the nixies for enough to buy a much
newer (used) DRO, or to at least pay for the parts to replace the
nixies with LED displays - Nixies are getting pretty dear. A simple
diode matrix will turn the nixie drive into an LED drive (for example,
from one pin per number to 7-segment), and you can adjust the power
supply from 90V to 5V by a minimal amount of work (there may even be
5V already available, just rewire)



On Fri, 13 Jan 2006 02:46:42 GMT, jabba wrote:

I bought a Index 645 that has a Baldwin DRO on it. This is
an old style with nixie tubes. The DRO has an independent
box for each the X and Y axis. The X axis worked fine, the
Y would not power up. I took it apart and fixed the power
supply to the nixie tubes and then it came on although one of
the nixies is burned out. Unfortunately there is some problem
in the logic chips I assume as the "zero" and "set" buttons do
not work correctly. Is anyone here experienced in fixing these
type of units or know where to get schematics?
Bill

www.wbnoble.com

to contact me, do not reply to this message,
instead correct this address and use it

will iam_ b_ No ble at msn daught com

It should be easy enough to reverse engineer the device.
Also nixie tubes are 10 segements devices. One line for each digit.
Mapping would be required as well as changing the supply voltage.
Simon Shabtai Evan




William B Noble (don't reply to this address) wrote:
you may find that you can sell the nixies for enough to buy a much
newer (used) DRO, or to at least pay for the parts to replace the
nixies with LED displays - Nixies are getting pretty dear. A simple
diode matrix will turn the nixie drive into an LED drive (for example,
from one pin per number to 7-segment), and you can adjust the power
supply from 90V to 5V by a minimal amount of work (there may even be
5V already available, just rewire)



On Fri, 13 Jan 2006 02:46:42 GMT, jabba wrote:


I bought a Index 645 that has a Baldwin DRO on it. This is
an old style with nixie tubes. The DRO has an independent
box for each the X and Y axis. The X axis worked fine, the
Y would not power up. I took it apart and fixed the power
supply to the nixie tubes and then it came on although one of
the nixies is burned out. Unfortunately there is some problem
in the logic chips I assume as the "zero" and "set" buttons do
not work correctly. Is anyone here experienced in fixing these
type of units or know where to get schematics?

Bill

www.wbnoble.com

to contact me, do not reply to this message,
instead correct this address and use it

will iam_ b_ No ble at msn daught com

jabba wrote:

I bought a Index 645 that has a Baldwin DRO on it. This is
an old style with nixie tubes. The DRO has an independent
box for each the X and Y axis. The X axis worked fine, the
Y would not power up. I took it apart and fixed the power
supply to the nixie tubes and then it came on although one of
the nixies is burned out. Unfortunately there is some problem
in the logic chips I assume as the "zero" and "set" buttons do
not work correctly. Is anyone here experienced in fixing these
type of units or know where to get schematics?

What is happening and what is not happening on the readout. Does it
change when you move the slider? does it always read the same numbers
no matter what is done? The old readouts are compariatively easy to
fix. chips are cheap. Determine the general area of the problem and
then change some chips in that area. If the reset doesnt reset some of
the numbers, the drivers probably have a short or the input to the nixie
drivers. Get an ECG book with the chip pinouts and check the logic on
the chips... or just replace them one at a time.

John

Mark Jones wrote:
jabba wrote:
I bought a Index 645 that has a Baldwin DRO on it. This is
an old style with nixie tubes. The DRO has an independent
box for each the X and Y axis. The X axis worked fine, the
Y would not power up. I took it apart and fixed the power
supply to the nixie tubes and then it came on although one of
the nixies is burned out. Unfortunately there is some problem
in the logic chips I assume as the "zero" and "set" buttons do
not work correctly. Is anyone here experienced in fixing these
type of units or know where to get schematics?

Curious here, are the nixies the only tubes present? Some tubes were actually
designed as logic devices and in fact the burned-out nixie could theoretically
affect the device operation. Not that it should have been designed that way
though.

No there's several dozen logic chips.

William B Noble (don't reply to this address) wrote:
you may find that you can sell the nixies for enough to buy a much
newer (used) DRO, or to at least pay for the parts to replace the
nixies with LED displays - Nixies are getting pretty dear. A simple
diode matrix will turn the nixie drive into an LED drive (for example,
from one pin per number to 7-segment), and you can adjust the power
supply from 90V to 5V by a minimal amount of work (there may even be
5V already available, just rewire)


I didn't look for an exact replacement yet but all the nixies I
saw online were in the $10-$20 range. Yeah I take them out and
sell them if I knew I had a buyer but that is probably unlikely
and I think they look cool anyway!

According to jabba :
I bought a Index 645 that has a Baldwin DRO on it. This is
an old style with nixie tubes. The DRO has an independent
box for each the X and Y axis. The X axis worked fine, the
Y would not power up. I took it apart and fixed the power
supply to the nixie tubes and then it came on although one of
the nixies is burned out.

I consider that highly unlikely. Nixies don't have a filament,
and don't "burn out" as a result.

If the glass is cracked, it will no longer have a (partial)
vacuum, and thus will not work.

It is far more likely to be the driver chips. Have you tried
swapping the supposedly "burned out" Nixie with one which still lights
up? I'll bet that the one which you considered burned out will light up
in another socket, and the "good" one will not light in the other
socket.

Unfortunately there is some problem
in the logic chips I assume as the "zero" and "set" buttons do
not work correctly. Is anyone here experienced in fixing these
type of units or know where to get schematics?

I have no schematics, and no experience with a Baldwin.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Just a note on Nixie driver chips. Experiences from the 60's

Most I have seen are working right at their breakdown voltage when the
element is off.

Most are open collector pull down outputs.

If you change chips install sockets if they are already present.

Details with chip numbers would help greatly. Pictures even better.

I don't recall ever having a Nixie fail, was always the driver.

Will help as much as I can online

Hugh



DoN. Nichols wrote:
According to jabba :

I bought a Index 645 that has a Baldwin DRO on it. This is
an old style with nixie tubes. The DRO has an independent
box for each the X and Y axis. The X axis worked fine, the
Y would not power up. I took it apart and fixed the power
supply to the nixie tubes and then it came on although one of
the nixies is burned out.


I consider that highly unlikely. Nixies don't have a filament,
and don't "burn out" as a result.

If the glass is cracked, it will no longer have a (partial)
vacuum, and thus will not work.

It is far more likely to be the driver chips. Have you tried
swapping the supposedly "burned out" Nixie with one which still lights
up? I'll bet that the one which you considered burned out will light up
in another socket, and the "good" one will not light in the other
socket.


Unfortunately there is some problem
in the logic chips I assume as the "zero" and "set" buttons do
not work correctly. Is anyone here experienced in fixing these
type of units or know where to get schematics?


I have no schematics, and no experience with a Baldwin.

Good Luck,
DoN.

Hugh Prescott wrote:
Just a note on Nixie driver chips. Experiences from the 60's

Most I have seen are working right at their breakdown voltage when the
element is off.

Most are open collector pull down outputs.

If you change chips install sockets if they are already present.

Details with chip numbers would help greatly. Pictures even better.

I don't recall ever having a Nixie fail, was always the driver.

Will help as much as I can online

Hugh


It may well be the driver and not the nixie. All I know at this
is that it doesn't work and I wrongly assumed it was the tube.
The driver is an SN7441AN which is a TI chip and I'm having a
hard time getting a data sheet.

jabba wrote:
Hugh Prescott wrote:

Just a note on Nixie driver chips. Experiences from the 60's

Most I have seen are working right at their breakdown voltage when the
element is off.

Most are open collector pull down outputs.

If you change chips install sockets if they are already present.

Details with chip numbers would help greatly. Pictures even better.

I don't recall ever having a Nixie fail, was always the driver.

Will help as much as I can online

Hugh


It may well be the driver and not the nixie. All I know at this
is that it doesn't work and I wrongly assumed it was the tube.
The driver is an SN7441AN which is a TI chip and I'm having a
hard time getting a data sheet.
Google:
7441 ttl "data sheet" "bcd to decimal"
Second result (unicornelectronics) has a link to the data sheet.
First result is worth reading for general background if you aren't a
Nixie enthusiast.

I would expect a high voltage OC driver to fail shorted, but I belive
you said the offending nixie wasn't lighting. I'd check if there is a
70 to 80V feed from the HT rail to that tube's anode via a limiting
resistor which may well have failed open. 7441 & 7441A have NO blanking
feature so should always show something on the Nixie if the tube and the
chip are both getting power.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
[dot]=.
*Warning* SPAM TRAP set in header, Use email address in sig. if you must.

Hugh Prescott wrote:
Just a note on Nixie driver chips. Experiences from the 60's

Most I have seen are working right at their breakdown voltage when the
element is off.

Most are open collector pull down outputs.

If you change chips install sockets if they are already present.

Details with chip numbers would help greatly. Pictures even better.

I don't recall ever having a Nixie fail, was always the driver.

Will help as much as I can online

Hugh

Alright... nixies aside for a moment... First thing I noticed is
that the display changes when you move some of the thumb switches.
(This unit has s thumb roller switch for each nixie so you can set each
digit on the display. Then you press "Set" to send the selected numbers
to the display.) The display should only change when the set button
is pressed. I verified the output of one of the counter chips
(SN74192N) was changing without pressing the set button with my
logic probe. Then I verified that the LOAD line was not changing
when the rollers were moved. This happens for three of the five
counters. I think I may just replace them all. Your thoughts?

Hugh Prescott wrote:
Just a note on Nixie driver chips. Experiences from the 60's

Most I have seen are working right at their breakdown voltage when the
element is off.

Most are open collector pull down outputs.

If you change chips install sockets if they are already present.

Details with chip numbers would help greatly. Pictures even better.

I don't recall ever having a Nixie fail, was always the driver.

Will help as much as I can online

Hugh

Alright... nixies aside for a moment... First thing I noticed is
that the display changes when you move some of the thumb switches.
(This unit has s thumb roller switch for each nixie so you can set each
digit on the display. Then you press "Set" to send the selected numbers
to the display.) The display should only change when the set button
is pressed. I verified the output of one of the counter chips
(SN74192N) was changing without pressing the set button with my
logic probe. Then I verified that the LOAD line was not changing
when the rollers were moved. This happens for three of the five
counters. I think I may just replace them all. Your thoughts?

jabba wrote:
Hugh Prescott wrote:

Just a note on Nixie driver chips. Experiences from the 60's

Most I have seen are working right at their breakdown voltage when the
element is off.

Most are open collector pull down outputs.

If you change chips install sockets if they are already present.

Details with chip numbers would help greatly. Pictures even better.

I don't recall ever having a Nixie fail, was always the driver.

Will help as much as I can online

Hugh


It may well be the driver and not the nixie. All I know at this
is that it doesn't work and I wrongly assumed it was the tube.
The driver is an SN7441AN which is a TI chip and I'm having a
hard time getting a data sheet.


7441 is a BCD(4 bit) to decimal(10) decoder 7447 is a BCD to 7 segment
decoder.

Where are you located as I may have some of them, will have to go deep
into the archives to see tomorrow.

Hugh

Hugh Prescott wrote:
jabba wrote:
Hugh Prescott wrote:

Just a note on Nixie driver chips. Experiences from the 60's

Most I have seen are working right at their breakdown voltage when
the element is off.

Most are open collector pull down outputs.

If you change chips install sockets if they are already present.

Details with chip numbers would help greatly. Pictures even better.

I don't recall ever having a Nixie fail, was always the driver.

Will help as much as I can online

Hugh


It may well be the driver and not the nixie. All I know at this
is that it doesn't work and I wrongly assumed it was the tube.
The driver is an SN7441AN which is a TI chip and I'm having a
hard time getting a data sheet.


7441 is a BCD(4 bit) to decimal(10) decoder 7447 is a BCD to 7 segment
decoder.

Where are you located as I may have some of them, will have to go deep
into the archives to see tomorrow.

Hugh

Hi Hugh... I responded to a different post of yours. I will repost it
here.

Alright... nixies aside for a moment... First thing I noticed is
that the display changes when you move some of the thumb switches.
(This unit has s thumb roller switch for each nixie so you can set each
digit on the display. Then you press "Set" to send the selected numbers
to the display.) The display should only change when the set button
is pressed. I verified the output of one of the counter chips
(SN74192N) was changing without pressing the set button with my
logic probe. Then I verified that the LOAD line was not changing
when the rollers were moved. This happens for three of the five
counters. I think I may just replace them all. Your thoughts?