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Dim Display

Last edited: 30 Sep 2009 

 

20 months on, and when I look at the display, I am convinced the brightness of the display has deteriorated (I believe it is a negative blue mode STN LCD display panel with LED edge backlight).  Even at maximum brightness setting, it is barely readable under normal day light. It is certainly no where near as bright as the display fitted to my Vistron MX-200i.  This deterioration may well be a consequence of leaving the Logik switched on albeit mostly on standby 24/7.

           

Above photo on left was taken when the radio was brand new.  Photo on right was taken 20 months later.

 

(Update: 30 Sep 09)

I observed there was a short article at horstedkeynes.com webpage offering IR100 repair services, where they described how to fix missing or dimmed lines on the display panel.  Admittingly, the fault on my display didn't resemble the example they showed on their webpage. My display was generally just difficult to read and dim overall.  However, this sentence that caught my eye was:

"Over time the sponges begin to deteriorate and flatten so you get poor connections, often improving as the radio heats up."

Any way, I thought I'd give it a go and dismantle the display panel using the instructions provided.

Well, the bad news after undoing the 6 tabs and wiggling the green PCB about, when I came re-tensioned and secured the tabs, I ended up with a slightly garbled display with dim or missing lines.  Aaarghh!!!   The screen messages were just about readable.

I then made things worse by dismantling the entire display assembly. (Sorry, forgot to take some photos)  Upon re-assembly, the display was virtually unreadable....     At this point, I was thinking to myself I had really f*ck*d up and I'd have to buy a new radio or get the old IR100 'professionally' repaired. 

I tried cleaning the contacts and re-assembling the panel half a dozen times to no avail.

 

An hour later, I finally got the display working again after a bit of analysis of how the display panel is manufactured, and bit of trial & error.

The following diagram shows how the display panel was originally assembled.

The conductive sponge (shown in grey) transmits the signals from the electrical contacts on the PCB to the corresponding contacts which appear to be screen printed onto the surface of the glass display matrix panel (shown in yellow).

The conductive sponge is actually 'compressed' between the PCB and the glass display matrix.

As the article at horstedkeynes.com webpage points out, the sponge deteriorates and becomes flattened as a result of heat and age.  In my case, dismantling the panel made the situation far worse.

I may be completely wrong, but I think there were three issues as to why I had so much trouble getting my display panel working again.

 

This perhaps isn't the correct way of repairing the display, but as I didn't have the right materials, I had to make do with what was available.  Also, I was becoming desperate...

Here is my bodged solution:

After a bit of trial and error using some thin sheets of cardboard (the stuff I used was about 0.2mm thick and is an old coloured separator page from a lever arch ring binder), I got the display working again within two attempts.  In fact, the first attempt was almost successful - the displayed messages were not garbled.

When refitting the metal bezel for the final time, I noticed I had to apply quite a bit of pressure to compress the conductive sponge before twisting the tabs to secure the bezel to the PCB.   In hindsight, it's possible my earlier attempts to sufficiently twist the tabs to secure the bezel were inadequate.  I wasn't about to dismantle the panel to remove my cardboard packing material and try reassembling again - I thought I'd best quit while I was ahead!   I thought I'd point this out in case it is a possible factor.

 

Did it fix my dim display?

Not as far as I can tell.

The edge lit backlight panel appeared to be working fine when I had the radio apart but whether the intensity at maximum setting is as bright as when the radio was brand new is open to question as I cannot compare with another working IR100.  I'm sure when I first bought the IR100, the display was so bright, I deliberately had to reduce the brightness setting.  The backlight comprises of two edge mounted LEDs which illuminate a flat rectangular light guide.

The contrast of the displayed messages may have improved a bit, but to be honest, it is not a significant improvement.

It's possible there is still a problem with the back lighting.  Either the LEDs have deteriorated or there is insufficient volts going to them.

 

 


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