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Need Tektronix TDS220 firmware file
Vorlon:
The same happened on my TDS220 with an Aliexpress LCD.
It seems they sell defective LCDs as "used ones".
Nprod:
I'm not sure if you can consider them defective or not, but the one i got certainly looked like it had been rusting away in a warehouse somehwere for a good 20 years. Even though both are labeled "LM32P073" there were differences in their PCBs - the original had about 3 small electrolytic capacitors on it while the aliexpress one has about 9, and they're bigger. There are also some differences in how the backlight bulb is housed. If i had to take a guess i'd say they're different revisions of the same model. Can you say which type the original and replacement screens were?
Perhaps these particular versions are designed for slightly lower contrast voltages, so a little resistor between the flex cable and PCB pad could bring it down to a more usable range that doesn't require you to set the contrast to 0% in the menu to make things visible.
JFJ:
--- Quote from: Nprod on July 11, 2019, 08:57:13 am ---... The LCD itself is not factory original, i got it from some old stock warehouse on aliexpress and it requires a low contrast setting to look correct for some reason...
--- End quote ---
It may be informative to compare the contrast control voltage range of your substitute LCD panel, with that of an original:
--- Quote from: JFJ on January 29, 2017, 08:26:39 pm ---On my TDS220, the Contrast buttons adjust the voltage on conductor 1 between -13.1V and -19.0V. The effect of this varying voltage is as follows:
-13.1V = A negative display (white-on-black)
-16.7V = A normal display (black-on-white)
-19.0V = A white display (completely washed out)
(the voltages are with respect to the main board ground connector).
NB With the ribbon cable only partly inserted into its connector (just enough to engage the contacts), sufficient conductor protrudes above the connector to take voltage measurements with a standard DMM probe.
--- End quote ---
Nprod:
@JFJ
Here's what i got:
Without a module installed:
SettingVoltageAppearance0%-18.8VGood15%-17.77VPoor contrast, display flips50%-16.16VBlank screen100%-13.55VBlank screen
With a module installed (TDS2MM firmware):
SettingVoltageAppearance0%-18.5VGood15%-17.71VPoor contrast, display flips50%-15.94VBlank screen100%-13.45VBlank screen
As you can see, the module doesn't affect the contrast voltage by a significant amount and the screen's response is the same. The reason i got a blank screen when first installing the module is because the scope's setting reset itself to 50%, not because of a voltage drop. Changing the EPROM possibly made the scope think it's a different module.
About the contrast - the datasheet for the LM32P07 (attached) states in its electrical characteristics (Table 4) that the contrast adjust voltage should be between 17.5V and 25.5V, with a typical setting of 21.5V. That would mean that the LCD is acting as it should, but the voltage the scope provides is too low.
clauditaolivia:
--- Quote from: OH2LIY on February 27, 2018, 07:22:57 pm ---Success! Bend flash pins 1 and 31 up (can be done once). Then use narrow tape strips between flash and socket pins (I used capton, it worked nicely), and just solder flash pin 1 to U104 pin 4 and flash pin 31 to closest VCC (pin 32 is closest, just bridge them).
Ramppa
--- End quote ---
Hello.
This is my first time on the blog. I need to upgrade my tds2cm module to tds2mm, but the speed of my new chip ram is 70 ns and the seller send me an amc27c040 120ns. Can i use them? Does the speed between the ram chip and the memory maters? (I´m not an electronics expert just an amateur) I noticed you( OH2LIY) used an am29f040b -90ns(well i think so because of your photos). I hope you can help me. Cheers from Mexico
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