Repair Guide: ZD-939 Hot Air Rework Station

This article describes how to repair a common failure on the ZD-939 hot air rework station caused by mechanical damage. Require ˜60 Minutes to clean and fix..

Root cause:

• free flight from ˜80 cm height from the table

After the impact, the device stopped working due to broken solder joints and lifted PCB pads.

• Device powers but not possible to set the temperature and display is not working
• Intermittent operation
• after unscrewing the devise visible damaged on 2x solder joints near transformer area

The failure occurs in the main power section (230V AC) < !!! DANGER !!!>.

Heavy components like the transformer create mechanical stress. After the fall:

• Solder joints crack
• Copper pads detach from PCB
• Electrical connection is lost

This repair involves mains voltage (230V AC).

• Disconnect power before opening
• Do NOT work on live circuits (a burnout in the IT sphere is something different then in the electric area)
• Ensure proper insulation
• Risk of electric shock and fire

• Screw driver Philips
• Soldering iron
• Solder (with flux)
• Copper wire (0.5–1 mm) or component leads
• Multimeter
• Optional: heat shrink or hot glue

Identify:

• Broken solder pads
• Broken pins
• Damaged traces
• Affected pins

Follow the copper trace from the damaged pad:

• Find next valid solder point
• Ensure it belongs to the same electrical path Only connect points on the SAME trace.

• Prepare short wire
• Tin both ends
• Solder:
  • Transformer pin → valid trace point

Keep wire:

• Short
• Direct
• Clean

• Cover exposed wire
• Use heat shrink or glue
• Avoid contact with other traces

Before power on:

• Check continuity (multimeter)
• Check for short circuits

Then:

• Power on carefully
• Observe behavior

If done correctly:

• Electrical connection restored
• Device operational again