The Circuit Specialists CSI-906 is a popular hot air rework station for hobbyists due to its extremely low price ($99).
One problem that can be encountered is that the air pump begins working intermittently. The symptoms are a loud noise and decreased hot air flow.
This problem should be repaired as soon as it occurs because damage will occur if it is allowed to continue. The cause is a nut backing off the motor shaft because it was not secured with proper thread locking compound at the factory.
To repair the problem:
- Remove top cover of CSI-906 by removing all phillips head screws from both sides.
- Remove air pump module in black plastic housing by pushing four rubber vibration absorbers up and through the base of the unit.
- Two pump chambers, with covers secured with four screws each and on opposite sides of the pump motor, will have to be examined. To access the four screws for second pump chamber, slide off the zip tie and remove the housing it secures.
- Examine each chamber for loose shaft nut, bushings, and torn diaphragm. If diaphragm is torn, it will need to be repaired or the air pump module replaced. If diaphragm is not torn, remove 5mm motor shaft nut and ensure both steel and plastic bushings are aligned on their respective guides (3ea).
- If shaft nut was loose or fallen off, examine and repair threads on motor shaft as necessary. If end of shaft is damaged, shaft can be cut off up to 1/8″. If shaft stud is damaged more than 1/8″, replace it. Regardless of condition, reinstall nut after applying red thread-locker compound and snug the nut.
- Clean any debris from pump chambers, reinstall covers, reassemble CSI906, and test for proper operation.