Chinese soldering station calibration procedure? YCD-8582D

[agent29]

Hello,

I acquired this second hand cheaply off eBay. I wasn't expecting much in the way of accuracy from its reported 200 degree to 480 degree range from the iron, however I was disappointed to discover the soldering iron was considerably inaccurate in relation to what it displayed.

Upon inspection there are two 1K pots on the PCB configured around lm358's, one for the hot air gun and one for the iron. My issue however is the linearity of the measured temperature. If the iron is set to lets say 480 degrees the display and temperature match within a few degrees, (this was its calibration setting when received). However when set to 200 degrees the temperature of the iron is some 50-60 degrees above what's displayed.

I adjusted VR1 (pot for iron) and manage to find a mid point around 330 degrees which provides an approximate equal +-30 degree deviation displayed at opposite ends of the temperature scale.

Is there a correct mode or method of calibrating the display / ADC values to the temperature? I have pressed both + and - keys simultaneously (which results in just reducing to minimum temperature), tried this whilst powering on and a number of different methods to no avail? Is there a calibration mode at all?

Can anybody assist?

Many thanks

[uhmgawa2]

There are at least two design versions of this unit.  The earlier has adjustment pots on the PCB and the latter appears to support temperature calibration in firmware.  Here is a manual scan for the latter unit:  https://www.scribd.com/document/748177655/Mypovos-8588d-2-in-1-Soldering-Station