Difficulty

Difficult

Steps

14

Time Required

                          20 minutes

Sections

1

  • Ersa i-CON Display backlight LEDs
  • 14 steps

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Introduction

PRE-WU2495B-01

ED-5455-LED/A ROHS

0712FJB1094/0107/16

Anyway, since I couldn’t get new displays for reasonable price, I decided to replace burned backlight LEDs in the displays. I used LTW-108DCG-HS10 as replacement LEDs in this guide, but any miniature white LEDs with at least 1000 mcd luminous intensity should do. See step 14 for more information.

What you need

Step 1

              Pull off control knob
  • Pull off the control knob using flat-head screwdriver or similar tool.

Pull off the control knob using flat-head screwdriver or similar tool.

1024

Step 2

              Remove bottom screws
  • Flip the station over and remove 4 screws with T20 screwdriver. Then flip the station back and pull up the top cover.

Flip the station over and remove 4 screws with T20 screwdriver. Then flip the station back and pull up the top cover.

Step 3

              Remove display nuts
  • Remove 4 plastic nuts around the display with pliers or similar tool.

Remove 4 plastic nuts around the display with pliers or similar tool.

Step 4

              Disconnect the display
  • Carefully flip the display upwards. Then loosen the flat cable connector by pushing up small brown bars on both sides. Pull the flat cable from the connector.
  • If you have replacement display, you can simply connect in the new one. Then you can assemble the station back together and you’re done.

Carefully flip the display upwards. Then loosen the flat cable connector by pushing up small brown bars on both sides. Pull the flat cable from the connector.

If you have replacement display, you can simply connect in the new one. Then you can assemble the station back together and you’re done.

Step 5

              Locate the display backlight
  • Display backlight is hidden under white tape on the right side.
  • The second photo shows markings on the display.

Display backlight is hidden under white tape on the right side.

The second photo shows markings on the display.

Step 6

              Remove cover tape
  • Carefully remove the white cover tape. It’s best to use a knife or similar tool.
  • Make sure the golden flexible circuit board strip doesn’t bend upwards along with the cover tape!

Carefully remove the white cover tape. It’s best to use a knife or similar tool.

Make sure the golden flexible circuit board strip doesn’t bend upwards along with the cover tape!

Step 7

              Remove  cover tape
  • You can hold down the circuit strip with a knife or similar tool to unstick it from the cover tape.
  • Be careful if you decide to wash away strip glue residue with alcohol. If it seeps between various layers inside the display area, it may develop unsightly spots.

You can hold down the circuit strip with a knife or similar tool to unstick it from the cover tape.

Be careful if you decide to wash away strip glue residue with alcohol. If it seeps between various layers inside the display area, it may develop unsightly spots.

Step 8

              Unstick the circuit strip from the base
  • Carefully unstick the circuit strip from the plexiglass base with knife.
  • The strip is glued in with a thin transparent double-sided tape. Make sure the tape stays on the plexiglass base. If it tears away along with the strip, use knife tip to push it back onto the plexiglass.
  • Try to bend the strip as little as possible, otherwise it will be difficult to seat it back in properly later.

Carefully unstick the circuit strip from the plexiglass base with knife.

The strip is glued in with a thin transparent double-sided tape. Make sure the tape stays on the plexiglass base. If it tears away along with the strip, use knife tip to push it back onto the plexiglass.

Try to bend the strip as little as possible, otherwise it will be difficult to seat it back in properly later.

Step 9

              Desolder original backlight LEDs
  • Fold the circuit strip onto display’s back cover and weigh it down. This will reveal the faulty original LEDs and some resistors.
  • Place some heat-resistant material under the strip before soldering. If you melt display’s plastic back cover, it will develop unsightly spots. I’m using several sheets of paper in the photo.

Fold the circuit strip onto display’s back cover and weigh it down. This will reveal the faulty original LEDs and some resistors.

Place some heat-resistant material under the strip before soldering. If you melt display’s plastic back cover, it will develop unsightly spots. I’m using several sheets of paper in the photo.

Step 10

              Backlight schematics
  • I analyzed original backlight connections and it’s apparent why it fails: Chinese comrades who designed the display wanted to save some money and/or space and connected the LEDs in parallel.
  • Of course, every LED has slightly different threshold voltage. As a consequence, one of them draws more current and fails (burns open) prematurely. The remaining two LEDs are then subjected to even higher currents and burn soon afterwards, too.
  • Thus I decided to change the connection according to the lower schematic - I shorted the original 22R resistors and put a 220R resistor in series with each new LED.

I analyzed original backlight connections and it’s apparent why it fails: Chinese comrades who designed the display wanted to save some money and/or space and connected the LEDs in parallel.

Of course, every LED has slightly different threshold voltage. As a consequence, one of them draws more current and fails (burns open) prematurely. The remaining two LEDs are then subjected to even higher currents and burn soon afterwards, too.

Thus I decided to change the connection according to the lower schematic - I shorted the original 22R resistors and put a 220R resistor in series with each new LED.

Step 11

              Solder in new components
  • Fortunately, there is enough room on the strip to solder in new LEDs (red arrows) along with their 220R resistors (green arrows) on the original solder pads. It’s ugly, but it works. You have to use resistors in 0603 package to fit them into the available space.
  • Note that I also desoldered the original 22R resistors and shorted their pads with a thin wire (purple arrow).
  • You can verify that all three new LEDs work by connecting a 5V power supply onto “A” and “K” pads on the strip.

Fortunately, there is enough room on the strip to solder in new LEDs (red arrows) along with their 220R resistors (green arrows) on the original solder pads. It’s ugly, but it works. You have to use resistors in 0603 package to fit them into the available space.

Note that I also desoldered the original 22R resistors and shorted their pads with a thin wire (purple arrow).

You can verify that all three new LEDs work by connecting a 5V power supply onto “A” and “K” pads on the strip.

Step 12

              Seat the strip back onto base
  • Stick the circuit strip back onto plexiglass base.
  • Remember that the new components are a bit wider, so make sure the strip doesn’t bulge or stick out anywhere. If it doesn’t fit properly, unstick it and try a slightly different position.

Stick the circuit strip back onto plexiglass base.

Remember that the new components are a bit wider, so make sure the strip doesn’t bulge or stick out anywhere. If it doesn’t fit properly, unstick it and try a slightly different position.

Step 13

              Secure the strip with new cover tape
  • Secure the strip in place with new tape cover. I used brown electrical tape in this photo.
  • Then you can reassemble the soldering station.

Secure the strip in place with new tape cover. I used brown electrical tape in this photo.

Then you can reassemble the soldering station.

Step 14

              Final result
  • Here you can see comparison of original (left) and new backlight (center). The new backlight is slightly brighter than the original; you can use larger resistors (270 or 330R instead of 220R) to lower the brightness.
  • I also experimented with general-purpose VLMW11R2S2-5K8L-08 omidirectional LEDs. You can see the result on the station on the right - the display is rather dim and there is significant backlight bleed on its right edge, where the LEDs are located. Thus I recommend to use only directional, right-angle LEDs like LTW-108DCG-HS10.
  • Since new LEDs need lower current to achieve similar light output, they should outlast the soldering station. This “trick” is generally applicable; high-brightness LEDs always generate more light at 2 mA than ordinary LEDs at 20 mA. At the same time, they consume less power, generate less heat and last much longer.

Here you can see comparison of original (left) and new backlight (center). The new backlight is slightly brighter than the original; you can use larger resistors (270 or 330R instead of 220R) to lower the brightness.

I also experimented with general-purpose VLMW11R2S2-5K8L-08 omidirectional LEDs. You can see the result on the station on the right - the display is rather dim and there is significant backlight bleed on its right edge, where the LEDs are located. Thus I recommend to use only directional, right-angle LEDs like LTW-108DCG-HS10.

Since new LEDs need lower current to achieve similar light output, they should outlast the soldering station. This “trick” is generally applicable; high-brightness LEDs always generate more light at 2 mA than ordinary LEDs at 20 mA. At the same time, they consume less power, generate less heat and last much longer.

To reassemble your device, follow these instructions in reverse order.

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                    Pavel Hanak

Member since: 12/08/2016

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Dave Johnson - Aug 16, 2017

Reply

Thanks a ton. We have ~20 units in our facility and experiencing the same issue. I feel like writing a preventive action to ERSA. I’ve followed your steps, bought the LEDs and found some 120ohm (0603) resistors laying around. You are pretty accurate on the time. It’s about 20mins after you get the first couple done. The results are night and day (pun intended…lol). I do like the irons and they work great, but just one drawback is the display design. Huge cost savings to do them yourself, but you need to have a light hand, and don’t burn anything. I used 3 layer paper under the circuit, exacto blade and tweezers to peel the tape back. The recommended LED part number (LTW-108xxx) works great. Thanks for this awesome money saver, our employees are happy they can see the display again. You Rock!

Ricardo Heleno - Oct 7, 2018

Reply

Thank you for your detailled walktrough.

I have found two types of screen on my ersa icon1. Lucky me one of the screens had a sticker with the model identification and is equal to your screen. =)

The model is ES13BB0BMW, manufactured by EMERGING DISPLAY TECHNOLOGIES CORP.

The only place I could find it for sale was here:

https://www.questcomp.com/part/4/ES13BB0…

But i am still waiting for a quote, because unfortunly my screen is dead.

You can also find a link to the datasheet on the above link.

I attemped connecting the other screen, the different one, and found it to no work properly on the pcb. The text gets faint. Dont know why yet.

Hello Again,

I have just found the other display version. Is quite easy to find on the web.

AMG12864PR-G-B12WTDW

http://www.orientlcd.com/mobile/Product….

On the above link you can also find the datasheets.

It also looks like someone already figured it out befor me.

https://www.eevblog.com/forum/repair/rep…

However altough thee pcb is the same, there are some differences on the mounted components. A direct compatibility can not be possible.. Maybe even software is different.. I will walk through the displays datasheets and see what might be needed to ensure compatibility between the two versions.

If I can pull it out I will maybe do a walkthrough in this.

Ricardo Heleno - Oct 7, 2018

The LCD controller is the same on both LCDs .. SITRONIX7565P , meaning that software should be compatible.

Ricardo Heleno - Oct 10, 2018

The display from Orient is confirmed to work just by direct replacement. =)