My display on QCX+ died overnight, in such a way that it is hard to read.?
On picture 1-2 the morse decode should be all T's, and adjusting contrast, I can either get some more T's readable, or make frequency readable.?

Now I piggybacked another (older) QCX display on top, and that one reads perfect, so it all boils down to replacing existing?HD44780 with a spare one I already have.?

How would you do to unsolder 16 pins?? Not easy to cut as plastic in the way

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73 Christen Fihl, OZ1AAB

I put some spring tension on the parts to cause them to pull apart, and then make a big blob of solder and run it up and down all the pins till stuff starts moving. If you don't get it all, you should at least get them up far enough to cut all the pins off, and then it's easy.

73, Willie N1JBJ

You could try chipquik.? I personally haven't used it, but I've seen it used to remove chips from PCBs.? It uses a low melt solder that says molten long enough remove devices with a high pin count.

Task done... :-)?
I only killed one track, that needed to be there

I cut the display away from its solder points (Drimmel)
And mounted the pins one by one

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73 Christen Fihl, OZ1AAB

Seems like I did not press "Add picture" on original posting. Here it goes

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73 Christen Fihl, OZ1AAB

Break/cut/burn off the plastic, the display is a writeoff anyway.? Dremel tools and files are also good for this type of destructive disasssembly.
73, Don N2VGU

开云体育

Chip quick dissolves into the existing solder and creates a much lower melting point that lasts much longer in liquid state than solder itself, thereby giving you plenty of time to remove most components, I would try this first especially since I have some.

On Fri, Jul 15, 2022 at 09:40 AM, Christen Fihl wrote:

Seems like I did not press "Add picture" on original posting. Here it goes

Your repair looks better than mine...


On Fri, Jul 15, 2022 at 08:14 AM, Christen Fihl wrote:

How would you do to unsolder 16 pins?? Not easy to cut as plastic in the way

I destroyed a couple plated through holes on a QCX+ front panel trying to remove the LCD...

Best option:??
??? Get/use a desoldering station.?? Nothing like having the right tools for any job...
????
After watching Chuck Adams' videos with his Hakko desoldering iron, I was amazed.?
He could remove all the parts from a PCB, and the PCB looks almost brand new...

I couldn't afford a Hakko, but for half the price I found this one works well for me:
???

What's really interesting is, now I have a lot more fun experimenting.? With the desoldering tool, I can install, remove, install, remove, various components, testing different values, etc. WITHOUT fear of damaging the PCB.


73
km6wt

I am back, I am sad to say :-)
The replacement screen died on me after these few days.?
PCB is running 5Volt, so all seems ok.?
It died after 24/7 use for a few days, and on next powerup, it did not work.?
The display was from my Arduino junk box. I do have another one. The last one

Would really be nice having a socket for this :-)?

Picture shows dead one, and new replacement piggybacked
This time it will be easier to replace though

?
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73 Christen Fihl, OZ1AAB

I will give a hearty vote for desoldering alloy.? Chipquick or Fastchip both available on Amazon.

Both of them are essentially "Rose's alloy", which is available much cheaper in 1 pound ingots, also on Amazon.

Avoid "Wood's alloy"; it has cadmium which is somewhat toxic.

The huge advantage of desoldering alloy is that the work proceeds at lower temperature than regular soldering.

Damage to the PC board itself is what we need to avoid.? If a plated through hole (PTH) is damaged the board may not be repairable.? That depends on whether the PTH has a function-critical connection to an inner layer of the board.

Boards are damaged by dwell time at elevated temperature, and by mechanical stress, for example pulling on a component to remove it when the solder is not molten.

Use of desoldering alloy lets you release the solder joints completely, and at a temperature lower than regular soldering.

I have replaced 32-pin quad-flat-pack devices (the ATmega32p microcontroller) repeatedly on a couple of boards, and no damage resulted.

A hot air rework station is certainly another good solution, but in my opinion not as good a solution as desoldering alloy.? With a hot air station you are bringing the whole area, including the device being removed, up to soldering temperature to get all the solder joints to release.? If you need to preserve the removed device, that's not the best strategy.

The downside of desoldering alloy is that I believe (just my opinion, others may know more! !) you need to clean up the board afterward using solder wick braid to remove as much as you can of the weird alloy.? I assume it's better to reinstall your part with uncontaminated solder.

Some people mention doing the same kind of technique using large amounts of molten solder ... the solder-blob technique.? I don't like that because of the higher temperature solder requires to stay molten, and the longer time-at-temperature needed to keep all that solder molten so you can release the part.

Be gentle with the thermal stresses on your boards.