Manufacturer: Quantum, Quantum Fireball drive families: EL, EX, CR, CX, lct08, lct10, lct15
Malfunction signs: A drive operates normally for some time (from15 minutes to several hours), then it begins to hit its positioner against the limiting stop.
It is a very frequent malfunction in those drive families, it is caused by the chip controlling the spindle motor and positioner; the chip has poor quality of factory soldering (please see the table), overheats because of that and stops to function normally.
One peculiarity of the TDA5247HT (AN8428NGAR) microchip is the availability of space for soldering in the lower part of its case acting, by the way, as its heatsink. It accomplishes heat abstraction from the chip and its dissipation along the board. Thus mounting and removal of that chip should be performed using a thermal air unit.
To repair that malfunction, you should unsolder the chip, broaden the soldering pad as shown in the figure 9 (that work can be performed using a lancet for removal of a portion of protective layer), blanch it and the lower part of the chip and solder the latter back pressing its case gently during soldering in such a manner that solder shows through board openings on the other side. Then you should carefully flush the soldered location because that chip has high-resistance analog outputs and fusing agent residue may disturb its normal operation.
That method undoubtedly improves the thermal conditions of the chip but it does not yield positive results always. If a chip used to be overheated for a long time, its resoldering does not remedy the situation. In that case the chip should be replaced. It is advisable to replace it with an identical model offered by Panasonic and having better thermal characteristics. Such chips can be purchased at stores selling electronic components. Its price may vary from 5 to 10$.