Summary of CSI Premier 75W and Hakko 936 Solder Station Teardowns
This article compares the teardowns of the CSI 75W and Hakko 936 solder stations. The Hakko 936 utilizes analog circuits with operational amplifiers, potentiometers, a temperature sensor, and a triac controller. In contrast, the CSI 75W employs digital control via a microcontroller, an opto isolator IC, and features programmable timers. While both units exhibit high-quality workmanship, the CSI 75W uses lower-quality JWCO electrolytic capacitors. The author critiques the CSI 75W's design choices, questioning the necessity of an external 8 MHz crystal, an external EEPROM, and an ICSP plug header instead of simpler alternatives like pogo pin pads.
Parts used in the CSI 75W Solder Station:
- Microcontroller
- Opto isolator IC
- External 8 MHz crystal
- External EEPROM
- ICSP plug header
- JWCO electrolytic capacitors
- Triac
Parts used in the Hakko 936 Solder Station:
- Operational amplifiers
- Potentiometers
- Temperature sensor
- Triac chip controller
I did the teardown of the CSI 75W solder station as well as the Hakko 936. The Hakko of course had all analog circuits using operational amplifiers and potentiometers as well as a temperature sensor in the iron tip to signal back to a triac chip controller which would trigger the triac to push 24 V AC through the heater in the iron. The CSI 75W was all digitally controlled with an internal microcontroller which was reading the temp sense line and switching the triac on/off through an opto isolator IC. And because it had a microcontroller it was also able to have the programmable set points and programmable sleep and power off timers.
The workmanship found in both soldering stations showed quality construction, soldering and manufacturing. I did not see any sloppy messy joints or poor workmanship. Most items were quality parts with the exception of the JWCO electrolytic capacitors in the CSI 75W.
For a device that was trying to save cost at any expense I found it strange that they did not use the internal oscillator in the microcontroller. I don’t see the point of having an external crystal running at 8 MHz when you could use an internal 8 MHz oscillator in such a design. If you’re not doing data communication and other high-speed tasks then an internal oscillator is more than accurate enough timekeeper. Maybe they needed this because they knew they were going to have to program and calibrate the microcontroller after production and the accurate timekeeping was necessary for the programming communications.
Also, the S3F8S19 microcontroller they used was able to store data in a small section of flash so why they needed or felt they needed an external EEPROM is a mystery to me. And when you’re trying to save costs why would you include an ICSP plug header or any other such unused connector when simple pogo pin pads would be just fine for after production code updates or calibrations.
For more detail: CSI Premier 75W and Hakko 936 Solder Station Teardowns
- What components does the Hakko 936 use for temperature control?
The Hakko 936 uses operational amplifiers, potentiometers, a temperature sensor in the iron tip, and a triac chip controller. - How does the CSI 75W switch the triac on and off?
The CSI 75W switches the triac on and off through an opto isolator IC controlled by its internal microcontroller. - Can the CSI 75W be programmed with specific timers?
Yes, the CSI 75W can have programmable set points and programmable sleep and power off timers due to its microcontroller. - Which capacitor brand was identified as poor quality in the CSI 75W?
The JWCO electrolytic capacitors were the only items identified as not being quality parts in the CSI 75W. - Why might the designer have chosen an external crystal over an internal oscillator?
The author suggests they may have needed accurate timekeeping for programming communications or calibration after production. - Does the S3F8S19 microcontroller support data storage without an external chip?
Yes, the S3F8S19 microcontroller is able to store data in a small section of flash memory internally. - What alternative could replace the ICSP plug header for code updates?
Simple pogo pin pads would be just fine for after production code updates or calibrations instead of an ICSP plug header. - Is the workmanship in both soldering stations considered sloppy?
No, the workmanship in both stations showed quality construction, soldering, and manufacturing with no messy joints.
