Beomaster 6000 Display Repair - Practice Does It!

I decided that I also needed to put new LEDs into the input/program selector display of my Beomaster 6000 to make both displays appear exactly the same. There is a very slight color difference between the old and the new SMD LEDs...the new ones are very slightly more orange...I am thinking one could probably fix this by using a bluish filter instead of the gray one I put into the frequency display...well, something for the next days. Now on to replacing the LEDs:

After removing the display and opening it up, I scraped the old LEDs out with a scalpel. This works very well. If it is moved parallel to the pads, it is virtually impossible to damage them. Then I studied a few more SMD soldering videos by Norman Mier on You Tube. I used his "dry tack" method to first fix the LEDs in place. To do this one first places a generous amount of rosin on the pads. Then grab the LED with precision tweezers and put it in an aligned location between the pads. Then take a very small amount of solder with the iron tip and briefly touch one side of the LED. After doing this with all of the LEDs, I then did Norman's "put solder wire halfway across the SMD tab to be soldered, and move the tip quickly in from the outside towards the pad". I held the tip for about 0.5 sec in place touching the LED to ensure good solder flow and bonding. The temperature of the iron was set to 340C. Here are a couple of pics of the result-much nicer than the mess I generated with the frequency display:

Even if some of the LED pads appear to be not coated by solder on the pic, they are. It seems that the pads usually only get a fairly thin coating during this soldering process. I tested the LEDs for mechanical stability with a tooth pick, and I was not able to damage the bonds even with quite some force.

Here is a picture of the display running. I plugged the pins into the female plug of an old parallel computer cable. The female plug at the other end of the cable was then connected to a breadboard's pos and neg rails with individual breadboard jumpers.

Beomaster 6000 Display Repair - Pain and Suffering!

****note: This post is 'historic'...Please, visit this page for my latest display repair procedure: http://beolover.blogspot.com/2012/09/beomaster-8000-display-repair-hopefully.html****



I guess I was too happy too early with my Beomaster 6000 display repair...While the LEDs survived my 12 hrs stress test under full load, they did not survive putting the apertures and lenses back on...two solder joints failed. I realized that the low temperature soldering paste did not work very well...after watching a few more SMD soldering tutorials by Norman Meir (yes, I am a fan!!) on youtube it became clear to me that I had to re-solder all of them. I doused everything in rosin flux and re-soldered with a fine tip at 340C using standard 60/40 solder (sparingly). It turns out that one needs to put the tip on the pad for about 5 sec to heat the part high enough that the solder actually flows on the contact pads of the LED. I tried not to touch the LEDs directly to avoid damage. This seemed to work fairly nicely. After wiping the board with alcohol it looked like that:

I tested each LED with a toothpick for mechanical stability. They seem to hold quite a bit of force without damage now...I hooked them up again to my connection manifold and turned them on:

We will see tomorrow, if they survived this torture. I must have heated each of them up about 10 times by now...