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I was not opposed to the clocks brightness witj the jumper installed but decided to add the 220k resistor at R4.

there are three holes at R4 reference designator. the jumper appears to be installed in the top two while the silk screen shows the resistor in the top and bottom hole.

after installing the 220k resistor the trimmer for the display does not appear to be any less sensitive.?

Have I done this mod wrong? I can certainly live with it but I expected a different result.
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regards,
Bryan, N0LUF

I may have answered my own question.
I'm wondering if the 220k resistor needs to bridge over two holes instead of one. I have one lead of the R4 the resistor in the top hole where the jumper was and then slipping over one moving down,? if that makes sense. there is only one blank hole under the resistor.?
Anyone?

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regards,
Bryan, N0LUF

On 15/01/2024 17:01, Bryan Curl wrote:

Anyone?

Bryan,

The manual says

a) A 220K resistor at R4 (this resistor is not
supplied in the kit, OR
b) A jumper wire in the position shown, and
NO R4.

The picture shows 4 holes.
Looks like the jumper takes 2 middle holes, the resistor spans where the jumper was.

I reckon if you put the jumper in the 2 top holes then the control would not work.
Degree of contrast random.

73 Alan G4ZFQ

Thanks Alan.
I read and understood the manual with regard to the jumper install but misread the pcb layout for the resistor.?

I will move the one leg of resistor to the top hole leaving 2 unused jumper holes open under the resistor.?
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regards,
Bryan, N0LUF

Looking at the pcb the top 2 holes are joined with a trace. the 3rd hole has a trace running off somewhere and the bottom hole, I can't tell. If it has a trace its on top side.

I tried using hole 2-3 and 2-4. either way a pretty sharp adjustment curve on the trimmer. I guess it is what it is and that's okay. So I'm moving on to other toys. maybe Ill add some temp sensors.?
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regards,
Bryan, N0LUF

Even with 220K the contrast adjustment is super sensitive?

the centre holes are for the jumper or the outer holes for the resistor?

Thanks Bruce. Good to know. from the schematic I could not see how I could have got it wrong.?

Onward and upward. :-)
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regards,
Bryan, N0LUF

I believe this is a brightness not contrast resistor.? I wired it to a 250Ohm pot and installed on the back of my enclosure so I could vary the brightness at will.

Bob
KG5GTE

Hi Bob. thanks for the idea.
Its called contrast <improvement> in the manual but either way it certainly effects brightness at extreme settings.
I'm okay with it as is. I found a 220k in the junk box and thought I'd put it in. It just didn't have the expected result.?
I wired the extra front panel switch to turn it off but will repurpose that as soon as I find another use for it; I dont need it for that after all.

Not to derail the thread but I'm working on thermometers now. I want to install one inside the QCX+ to monitor BS170s on wspr. we will see if rf upsets them.?

These kits are so fun and versatile. Hans has sure cornered the market on cool toys to learn with.
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regards,
Bryan, N0LUF

\unless we are talking about different things, contrast is a small pot on the LCD board.? There were three or four options, on the version 1 using different resister values and or locations for brightness.

Bob