Casio SDB-500 (Blue) – Restoration

The story of this Casio SDB-500 (Blue Version) continues the same Swedish Casio lot that started this whole series. On The Casio Vintage Club Facebook group, I found a post from a collector in Sweden who was selling a batch of Casio watches from the 80s and 90s. All of them were not working and in average condition. I selected six models for restoration. Two of them are already done, the TGW-10 Restoration and the TS-200 (Black) Restoration. The next one on my bench was the Casio SDB-500 with blue buttons ⌚.

The SDB-500 always stands out. Bold colors, sporty design, and a very strong 90s Casio feeling 👍. I already restored this model in the white version before, so I knew what to expect. At the same time, this blue version had its own challenges. Some good signs, some bad surprises. That mix is exactly what makes vintage Casio restoration interesting 🛠️.

What was the initial condition of the watch?

At first look, the Casio SDB-500 (Blue) was in rough shape ⌚. The watch was not working, and someone fitted a fabric strap, which makes no sense for this model 😅. The resin case was scratched, and the acrylic crystal showed heavy wear. Dirt and old grime were packed into the gaps and edges.

The biggest problem appeared right away. The watch had one broken lug. This made the restoration more difficult than the previous two projects. Structurally, broken lugs are always a serious issue. On the positive side, after opening the caseback, I found an original Toshiba battery made in Japan. This was a good sign. There was no corrosion, and the module looked clean. The outside needed a lot of work, but the heart of the Casio SDB-500 still had potential 👍.

Does the module still work? First power test

Before any repair work, I checked the module 🔧. I removed the fabric strap and opened the case. Just like the other watches from this lot, the Casio SDB-500 still had an original Toshiba battery made in Japan inside. I replaced it with a fresh one and performed a standard AC reset.

The result was instant and very satisfying 😅. The display showed 12:00 right away. All LCD segments were visible. The buttons worked correctly. At that moment, I knew the most important part was safe. A working module makes even a difficult restoration worth the effort 🛠️.

Restoration process

Once the module was confirmed working, I could focus on the hard part 🛠️. This restoration was more demanding than the previous two, mainly because of the broken lug.

Step 1: Case disassembly and cleaning

I fully disassembled the case.
This allowed me to clean all gaps and edges properly. Dirt was trapped everywhere, especially around the lug and case seams. After a full bath, the real condition of the resin was visible.

Step 2: Broken lug repair

This was the most important step.
The Casio SDB-500 had broken lug, so I had to rebuild the plastic structure.

• I used baking soda and super glue.
• This method allows the plastic to be rebuilt layer by layer.
• After curing, the area becomes strong enough for shaping and sanding.

I documented this repair method step by step in a separate video. It is linked on my YouTube channel 👍. Link below:

Step 3: Resin case sanding

After restoring the lug, I moved to sanding the case.
I used sandpaper from 1000 grit to 2500 grit. The goal was to remove scratches and blend the repaired areas with the original resin. I worked slowly to keep the correct shape and edges.

Step 4: Acrylic crystal restoration

Next was the acrylic crystal ⌚.
I sanded it up to 7000 grit to remove deeper scratches. Then I polished it with felt and Polywatch. The crystal became clear again without losing its original form.

Step 5: Final case finish

To finish the case, I used a white magic sponge.
First dry, then slightly wet. This step restored an even, matte surface that matches the original Casio finish 👍.

Step 6: Strap installation

Luckily, this time the story had a happy ending.
The original strap for the Casio SDB-500 is still available. I ordered a new one and installed it without any issues. No fitting, no compromises. Just the correct strap for the model ⌚.

At this point, the watch was ready for final assembly.

The final result

After final assembly, the Casio SDB-500 (Blue) looked much better than I expected ⌚. The resin case is clean and even, with a proper matte finish. The acrylic crystal is clear again, without deep scratches. The repaired lug blend well with the case and feel solid. You would not guess they were broken before 👍.

Technically, the watch works 100%. The module runs perfectly. The display is clear. All buttons respond correctly. With the original strap installed, the watch finally looks complete and correct for this model. This SDB-500 is no longer a problem piece. It is a fully wearable vintage Casio again 🛠️.

Broken lugs often scare collectors away. This project shows that, with the right method and patience, even serious damage can be fixed.

Want your Vintage Casio restored? I also work on collector projects 👍

The Casio SDB-500 (Blue) is one more example of the restorations I do ⌚. I also restore vintage Casio watches for other collectors. You can see examples of my previous projects here:
👉 https://casiorestore.com/projects-restorations/

I work internationally, and shipping is not a problem. I have already completed restorations for collectors from the UK, Sweden, Poland, and France. Every project is discussed individually, so we always agree on the scope, price, and shipping before starting 🛠️.

The process is simple:

• Write to me on Instagram: @vintage.casio.restore
• Or send me an email: vintagecasiorestore@gmail.com
• Describe the problem with your watch
• Send clear photos
• Tell me your country

If your Casio deserves a second life, I will be happy to help 👍