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15.4" T61 LED Screen Options, Voltage

T60/T61 series specific matters only
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15.4" T61 LED Screen Options, Voltage

#1 Post by dances_with_woof » Sun May 24, 2020 4:40 pm

For the Widescreen, 16:10 15.4 Inch model, I've read that almost any panel meant for this format with compatible plugs will work. I'm very interested in getting one with an LED backlight. Is there a popular one for this application, and will it require voltage adjustment to switch between CCFL and LED?

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Re: 15.4" T61 LED Screen Options, Voltage

#2 Post by atagunov » Sun May 24, 2020 6:17 pm

I've been looking into a very similar question. I'm considering HV150UX2-100 (a 4:3 15") for use in T60/T61 Frankenpad
It's got an "ex-factory" (factory-installed) LED backlight

The small long PCB inside the display known as "inverter" needs to be modified
From the information I was able to gather in a day

- it's possible to continue using stock board or a one identical to it
- people who install HV150UX2-100 into T60 often (always?) solder 4 wires between inverter and HV150UX2-100
- 4 wires are: GROUND, POWER SUPPLY (thick wires), backlight on, PWM control (thin wires)
- soldering wires onto the inverter board is not that easy because soldering pads are tiny, same with the panel
- it is additionally advisable to remove transformer (link) from the inverter board to save power and prevent overheating

Venerable RealBlackStuff is kindly offering the service of modifying display cables (connector on your panel is the other thing you need to consider btw) and modifying inverters. Modifying inverters is probably the easier part which we could potentially try ourselves..

Here's an interesting quote:
RealBlackStuff wrote:
Tue Aug 12, 2014 2:41 pm
For the "LED-mods" that I did (BoeHydis HV150UX2-100 with LEDs ex-factory), I used these standard T60p inverters for UXGA screens:
- 42T0078 / 42T0079 or 41W1012 / 39T5658 (both made by Hitachi, also have marking INVC753)
- 13R1014 / 13R1015 (made by Sumida)
Even though these BoeHydis LEDs can take up to +29VDC, I only passed on the +5VDC that is available on those inverters.
These screens are superbright, even at 5V!
Maybe you should lower the voltage?
I thought 20V was also available on the inverter board.. But I'm not sure now..

For me there are two concerns:

- is 5V the right voltage for HV150UX2-100? say for direct sunlight?
- am I going to notice any flicker with this kind of mod?

Re flicker
- it seems the way motherboard is communicating the desired brightness to the inverter is via PWM
- it seems the PWM frequency here is set in software; it seems Linux is using 200Hz by default
- it seems that under Windows it can be set by some additional application and otherwise defaults to 50-60Hz
- even though the problem seems kind of solved with this 200Hz people still applied other fixes; the fix in the link is applied not to the stock inverter but to some other model sold somewhere on the net

And the main question for me is if modifying the stock inverter is really the best option or if we should look for alternatives. People have been purchasing LED Modification Kits for their Thinkpad screens. Those kits consist of a strip of LEDs and a new inverter. The buyer is supposed to super-carefully remove the CCFL tube from his panel and push in the LED strip instead. I understand the result is usually a bit inferior to "ex-factory" LEDs. E.g. sometimes people see individual LEDs slightly visible along the bottom edge of the screen. The evenness of lighting is less than that on ex-factory LED panels. Mainly for this reason I have decided against doing this mod myself. People also say it's rather difficult. What is interesting for me here is that some other inverters are being produced somewhere in the world.. Which could potentially be usable with HV150UX2-100. I read (some?) of these kits only offer 1:5 range of brightness adjustment compared to 1:25 on stock CCFL screens. I don't know which of them offer the right voltage range for HV150UX2-100. I'm also somewhat afraid to ruin an again somewhat expensive panel :)

I'm wondering if it's easier to stick to CCFL.. It's definitely cheaper and less hassle..

P.S. just so that I do not loose it here's a link to another related topic
X220, 2 *T520

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