Calibrating YIHUA 898D soldering station

When you buy an 898D soldering station there's a very high chance that it is completely uncalibrated, leading to burnt/damaged parts and other kinds of problems since most of the times it is calibrated to give much higher temperature.

For that procedure you are going to need:

• A cross-head screwdriver to open the 898D
• A flat-head screwdriver at most 2 mm wide to rotate the potentiometers
• A thermocouple thermometer
• An IR thermometer

First of all , set both temperatures at 230 C° and disconnect the power cord because part of the board is directly connected to mains

To open the soldering station , remove the four screws around the front panel

Once removed the front panel you should have a board like the one below:

That board has two trimmers, one is to adjust smd rework gun , the other one is to adjust soldering iron temperature.

First start with hot air gun, after you made sure that no metal is touching the board and you are not touching the board, plug the power again, and heat a piece of paper with the hot air gun.
Place on one side of the paper the hot air gun, on the other side an IR thermometer.
If you read 220-235 C° it's ok, if you read temperatures like 260 or 280 C° or 200 C° you definetely need to adjust it.
To do that take a small flathead screwdriver and with the soldering station disconnected from mains if the air is hotter than it should be , rotate like 1-2 turns the potentiometer counter-clockwise, otherwise rotate it of the same amount clockwise, and plug again the power and check if the temperature is in an acceptable range, if not repeat the above step with smaller adjustements.

When you have done with hot air gun start working on the soldering iron, place some excess solder on it's tip and put it in contact of a shielded thermocouple

Let it stay like 3-4 mins and then check the temperature reading of the thermocouple, if it is less than 210 C° or more than 240 C° you need to calibrate that too, proceed as follows:

1. If temperature is higher than it should be, rotate like 1/4 of turn the soldering iron potentiometer clockwise ( contrary to the hot air gun one ), you should do that with the power connected so BE VERY CAREFUL to not touch any part on the board except the potentiometer with the screwdriver when doing that.
   If the temperature is lower than it rotate it 1/4 of turn counter-clockwise.
   
2. If temperature was higher than needed, blow some air at the thermocouple+soldering iron tip to lower the temperature and wait for it to rise
3. After like 2 minutes, check if temperature still needs adjustement, if yes repeat from step1 with smaller rotations.

I'm using a pid controller as a thermometer because it's the only thermocouple based thermometer that i have at the moment

After that reassemble everything and you are done.