TDS2000 brightness control


Tom B
 

Hello All,

I picked up some really cheap ($3.95 at Electronics Goldmine) displays that work in the TDS2000.  The problem with it is that is looks like the backlight is too bright.  The only way that I found in the manual to control brightness is through the RS-232 or 488 ports.  Does anyone know if there is a way to control brightness from the front panel ?

If anyone is interested, the part number for the display is MTV-F32240AMNNSCW-H-1.  It was made by Microtips.  There are some on ebay, but at slightly higher prices.   I have not been able to find a datasheet on it.

Tom Bryan
N3AJA


Tom B
 

I read the manual a little closer.  The brightness command only works on the TPS2000, not TDS2000.  I guess I am out of luck.

Tom

On 3/1/2020 8:06 AM, Tom B wrote:
Hello All,

I picked up some really cheap ($3.95 at Electronics Goldmine) displays that work in the TDS2000.  The problem with it is that is looks like the backlight is too bright.  The only way that I found in the manual to control brightness is through the RS-232 or 488 ports.  Does anyone know if there is a way to control brightness from the front panel ?

If anyone is interested, the part number for the display is MTV-F32240AMNNSCW-H-1.  It was made by Microtips.  There are some on ebay, but at slightly higher prices.   I have not been able to find a datasheet on it.

Tom Bryan
N3AJA


satbeginner
 


Tom B
 

Yes, that is what I got.  They do work in the TDS2000 but I think the backlight is a bit too bright.  There doesn't seem to be any way to change it short of getting rid of the CFL bulb and putting in LEDs.

Tom

On 3/1/2020 3:49 PM, satbeginner wrote:
Using Google I found this:


https://urldefense.com/v3/__https://www.goldmine-elec-products.com/prodinfo.asp?number=G19815__;!!KfGNmQmE!2zITbJD8FLS3gsRdikglcjy87OGTVu2u5BokwWCSWXYZg5hobW2T6AVS4oDo$


satbeginner
 

Usually these CFL inverters used for the backlight (at least in laptops) have an analog pin to adjust the brightness of the CFL, also there should be some room to play with using the contrast setting of the LCD itself.
I do not have such a device, but I changed both display and inverter in a Tektronix THS710 a long time ago having to do something similar.

Succes,

Leo


Harvey White
 

You can do that, possibly.  It depends on whether or not the display has an easily replaceable CCFL bulb.

What you'd need would be an LED strip, the appropriate resistors and LEDs.  You'd need a variable PWM source or perhaps an additional resistor/variable voltage regulator to give you the brightness you want, or just adjust the resistors (which can get messy if you do it too many times).  You can adjust the resistors to work profitably on a 5 volt supply, for instance.

Another option is to replace the inverter with a variable brightness one, and put a small pot in to control that brightness.  If the existing configuration has the provisions for bright/dim the inverter, you may want to mess with that instead of putting LEDS in or replacing the inverter.

I have replaced CCFL lamps with LED strips, and do have LEDS and the blank PC boards, though.  You'll want to be able to do surface mount soldering, the parts are 1206 and 805 in size.

I'd look at messing with the control of the inverter first.  I would NOT mess with the high voltage part at all, you're talking 1600 volts at 8 ma or so to light that little CCFL lamp.

Likely the first thing would be to see what the inverter has in the way of a control voltage, for the ones I've seen, it's a simple voltage from, say, 0 to 4 volts.  Don't remember if more is less here, but that depends on the inverter.  Some are not brightness controlled, some are.

Harvey

On 3/1/2020 4:05 PM, Tom B wrote:

Yes, that is what I got.  They do work in the TDS2000 but I think the backlight is a bit too bright.  There doesn't seem to be any way to change it short of getting rid of the CFL bulb and putting in LEDs.

Tom


On 3/1/2020 3:49 PM, satbeginner wrote:
Using Google I found this:


https://urldefense.com/v3/__https://www.goldmine-elec-products.com/prodinfo.asp?number=G19815__;!!KfGNmQmE!2zITbJD8FLS3gsRdikglcjy87OGTVu2u5BokwWCSWXYZg5hobW2T6AVS4oDo$



Tom B
 

Unfortunately, it does not appear that there is any way to adjust the brightness.  They built the main power supply and CCFL inverter all on one board.  There is nothing to adjust.  The service manual specs the inverter output at 1400V P-P @5mA load.

I don't know if there is enough room inside to put a separate inverter for the backlight.  It might be better just to live with it the way it is.

Tom

On 3/1/2020 4:25 PM, Harvey White wrote:
You can do that, possibly.  It depends on whether or not the display has an easily replaceable CCFL bulb.

What you'd need would be an LED strip, the appropriate resistors and LEDs.  You'd need a variable PWM source or perhaps an additional resistor/variable voltage regulator to give you the brightness you want, or just adjust the resistors (which can get messy if you do it too many times).  You can adjust the resistors to work profitably on a 5 volt supply, for instance.

Another option is to replace the inverter with a variable brightness one, and put a small pot in to control that brightness.  If the existing configuration has the provisions for bright/dim the inverter, you may want to mess with that instead of putting LEDS in or replacing the inverter.

I have replaced CCFL lamps with LED strips, and do have LEDS and the blank PC boards, though.  You'll want to be able to do surface mount soldering, the parts are 1206 and 805 in size.

I'd look at messing with the control of the inverter first.  I would NOT mess with the high voltage part at all, you're talking 1600 volts at 8 ma or so to light that little CCFL lamp.

Likely the first thing would be to see what the inverter has in the way of a control voltage, for the ones I've seen, it's a simple voltage from, say, 0 to 4 volts.  Don't remember if more is less here, but that depends on the inverter.  Some are not brightness controlled, some are.


Mark Jordan
 

Or you can replace the backlight with white LEDs.

    Mark Jordan

On 01-Mar-20 19:49, Tom B wrote:
Unfortunately, it does not appear that there is any way to adjust the brightness.  They built the main power supply and CCFL inverter all on one board.  There is nothing to adjust.  The service manual specs the inverter output at 1400V P-P @5mA load.

I don't know if there is enough room inside to put a separate inverter for the backlight.  It might be better just to live with it the way it is.

Tom

On 3/1/2020 4:25 PM, Harvey White wrote:
You can do that, possibly.  It depends on whether or not the display has an easily replaceable CCFL bulb.

What you'd need would be an LED strip, the appropriate resistors and LEDs.  You'd need a variable PWM source or perhaps an additional resistor/variable voltage regulator to give you the brightness you want, or just adjust the resistors (which can get messy if you do it too many times).  You can adjust the resistors to work profitably on a 5 volt supply, for instance.

Another option is to replace the inverter with a variable brightness one, and put a small pot in to control that brightness.  If the existing configuration has the provisions for bright/dim the inverter, you may want to mess with that instead of putting LEDS in or replacing the inverter.

I have replaced CCFL lamps with LED strips, and do have LEDS and the blank PC boards, though.  You'll want to be able to do surface mount soldering, the parts are 1206 and 805 in size.

I'd look at messing with the control of the inverter first.  I would NOT mess with the high voltage part at all, you're talking 1600 volts at 8 ma or so to light that little CCFL lamp.

Likely the first thing would be to see what the inverter has in the way of a control voltage, for the ones I've seen, it's a simple voltage from, say, 0 to 4 volts.  Don't remember if more is less here, but that depends on the inverter.  Some are not brightness controlled, some are.