There are circular holes on the ink cartridge, and the product trademark is generally attached. Tear off the trademark, insert it with a needle and take it out. Wipe it with white paper to see what color it is. Inject ink with a syringe. Don't inject too much, or it will overflow. The steps are as follows:

1. Confirm the ink injection point. Three colors of ink are ejected from three holes respectively.

2. Use three syringes to suck 2ml of ink from the ink bottles of three colors. The capacity of color ink cartridge is small, and the ink of three colors will not be used up at the same time, so do not exceed 2ml.

3. Inject three colors of ink according to the injection point confirmed in step 1. The filling process must be slow, so that the sponge in the ink cartridge can be easily absorbed. If overflow is found, stop immediately and suck out a little ink.

4. After standing for 10 minutes, confirm the ink injection effect on the folded toilet paper. Ink injection is successful and can be used directly.