Re: TDS3044B repair

David Kuhn

" there are commercially
available LED backlight kits to replace the CCFL lamps. "

I would be in your dept if you could point me to an LED replacement for the
fluorescent tubes in the NEC displays like that are used in the TDS3000
series (no bloody A, No bloody B or C). I'll get the actual NEC LCD part
number and reply again later. I wonder if the LED replacement is made to
run off the fluorescent tube inverter supply? I ask that because that
supply has software control line to control the brightness. LET is
probably off or on, unless it is designed to run off the inverter or a
software equivalent inverter is available (retrofitting old equipment not
designing new stuff).


On Tue, Nov 5, 2019 at 2:31 PM Harvey White <madyn@...> wrote:

On 11/5/2019 1:59 PM, David Kuhn wrote:
Sorry for the response delay.

I am in Lewistown, PA. How cheap are the displays and where are you
finding them? I have found the ones, used in the Ultrasonic instruments
mentioned, on Alliexpress, and EBAY (haven't ordered any from either
but I can not find the backlight tubes, which I find is usually the
with the displays. The displays may be just slightly different than in
TDS3032, but if so, only mechanically. The connectors are the same, and
really think the part numbers are the same. It's not a real easy
replacement in those TDS scopes. It looks easy, but it's a pain in the
Depending on the manufacturer of the display, there are commercially
available LED backlight kits to replace the CCFL lamps.

You may want to buy the TDS3GV on EBAY. I can't use a TDS3032 without
but I have written a lot of service software in VBA and VB6 that
automatically sets up the scopes and gets data from them. I can also
project my TDS3032 to the 32" TV mounted on the wall above it (an older
Sceptre with VGA input) and that's pretty cool.

Again, if the cables are seated well, I doubt the LCD is bad with an
all-white display. My thoughts are a main PCB issue. A TSD3GV could
me wrong.
If you find an all white display, then depending on the type of display
(positive or negative) you'd suspect no signals to it, or improper signals.

The display is likely to take either 5 or 3.3 volts, recent ones that I
have take 3.3. Older STN displays can take 5. The white is the result
of the backlight working, but no active pixels at all (hence no
polarization, etc....).

Like a CRT display, you'll be looking for a horizontal sync (at perhaps
30 Khz), vertical sync (say 60 or so Hz), a DE (likely at horizontal
rate and active high), and a pixel clock at about 25 or so Mhz. You'd
also expect supply voltages to be somewhere on the display. If the
timing is right and the voltages are there, then the display ought to be
showing something. If not, then look at the other pins, they should be
R,G,B digital signals, either in 565 (for a 16 bit panel) or 666 (for an
18 bit panel). If there's any activity on them, then with the right
sync signals, they ought to be giving something on the display.



On Tue, Oct 29, 2019 at 10:55 PM Tom B <tbryan@...> wrote:

Hi Dave,

I tried the "B Trig" and nothing happened. Displays are fairly cheap
but I don't want to buy one unless I have to.

Thank you for the offer. I would be a long while before I make it up
that way.

What town are you in?


On 10/29/2019 4:52 PM, David Kuhn wrote:
I'm in central, PA, about 3 hours from you if you ever want to come up
try it here with one of my VGA/GPIB modules.

Before that. Power it up while holding in the "B TRIG" button (might
different on the TDS3014), which on my TDS3032's causes a RESET. I've
that fix display issues after replacing the battery NVRAM in in the
The display in the TDS3032, is the exact same LCD used in the GEIT
XS and USN60 instruments. I have worked on many. I have never seen
LCD fail on those instrument where it's all white. Typical, if not
is smeary displays that lines seems to go out of sync. Dim, of course
broken backlight tubes.


On Mon, Oct 28, 2019 at 10:50 PM Tom B <tbryan@...> wrote:

Hi Rich (?),

Thanks. I am located in Maryland near Washington DC.

If anyone in the Washington DC area has a TDS3GV that I could come
and quickly test my scope with, I would appreciate it.

Tom Bryan

On 10/28/2019 10:29 AM, Oz-in-DFW wrote:
I'd still remove and reseat both ends.

Where are you in the world? I have a VGA/serial/GPIB card in my 3014
that we might be able to mate with your scope briefly.

Join to automatically receive all group messages.